Evidence-Based Weight Loss: Live Presentation
Why don’t we give a big, warm welcome
to Dr. Michael Greger! [Applause] Surely, if there was some safe,
simple, side-effect-free solution to the obesity epidemic, we would
know about it by now, right? I’m not so sure. It may take up to 17 years before
research findings make it into day-to-day clinical practice. To take one example that was particularly poignant for my family: heart disease. You know, decades ago, Dr. Dean Ornish
and colleagues published evidence in one of the most prestigious
medical journals in the world that our leading cause of death
could be reversed with diet and lifestyle changes alone—
yet, hardly anything changed.
Even now, hundreds of thousands of
Americans continue to needlessly die from what we learned decades
ago was a reversible disease. In fact, I had seen it with my own eyes. My grandmother was cured of
her end-stage heart disease by one of Dean’s predecessors,
Nathan Pritikin, using similar methods. So, if effectively the cure to our
number-one killer of men and women could get lost down some
rabbit hole and ignored, what else might there be
in the medical literature that could help my patients,
but that just didn’t have a corporate budget driving its promotion? Well, I made it my life’s
mission to find out. That’s why I became a doctor in
the first place and why I started my nonprofit site, NutritionFacts.org. Everything on the website is free. There are no ads,
no corporate sponsorship. It’s strictly noncommercial,
not selling anything. I just put it up as a public
service, as a labor of love, as a tribute to my grandmother. [Applause] New videos and articles nearly every day on the latest in evidence-
based nutrition—what a concept.
Ok, so, what does the science show
is the best way to lose weight? If you want testimonials and
before-and-after pictures, you have come to the wrong place. I’m not interested in anecdotes;
I’m interested in the evidence. When it comes to making decisions
as life-and-death-important as the health and well-being
of yourself and your family, there’s really only one question: What does the best available
balance of evidence show right now? The problem is that even just sticking
to the peer-reviewed medical literature is not enough as, “False and scientifically
[misleading] unsupported beliefs about obesity are pervasive”
even in scientific journals.
The only way to get at the
truth, then, is to dive deep into the primary literature and read all the original studies themselves. But, who’s got time for that? There are more than half
a million scientific papers on obesity with a hundred
new ones published every day. Even researchers in the field
might not be able to keep track beyond their narrow domain. But that’s what we do at NutritionFacts.org.
We comb through tens of thousands
of studies a year so you… don’t have to. Very nice! And indeed, we uncovered a
treasure trove of buried data, like today I’ll cover simple
spices, for example, proven in randomized, double-blind, placebo-
controlled trials to accelerate weight loss for pennies a day, but with
so little profit potential, it’s no wonder these studies
never saw the light of day. The only profiting I care
about, though, is your health. That’s why 100% of all the proceeds
I receive from all of my books, and DVDs, and speaking engagements
are all donated to charity.
I just want to do for your family
what Pritikin did for my family. But wait, isn’t weight loss just
about eating less and moving more? I mean, isn’t a calorie a calorie? That’s what the food
industry wants you to think. The notion that a calorie from
one source is just as fattening as any other is a trope broadcast
by the food industry as a way to absolve itself of culpability.
Coca-Cola itself even put
an ad out there emphasizing this “one simple common-sense fact.” As the current and past chairs of the
Harvard’s nutrition department put it, this “central argument” from industry
is that the “overconsumption of calories from carrots would be no different than the
overconsumption of calories from soda” If a calorie is just a calorie, why
does it matter what we put in our mouths? Let’s explore that example
of carrots versus Coca-Cola.
It’s true that in a tightly
controlled laboratory setting, 240 calories of carrots (10 carrots)
would have the same effect on calorie balance than the 240
calories in a bottle of Coke, but this comparison falls flat on
its face out in the real world. You could chug those liquid candy
calories in less than a minute, but eating 240 calories of
carrots would take you more than two-and-a-half hours of
sustained constant chewing. Not only would your jaw get
sore, but 240 calories of carrots is like five cups—you might not
even be able to fit them all in.
Our stomach is only so big. Once we fill it up, stretch receptors in our stomach wall tell
us when we’ve had enough, but different foods have different
amounts of calories per stomachful. Some foods have more calories per cup,
per pound, per mouthful than others. This is the concept of calorie density: the number of calories in
a given amount of food. Three pounds is about what the
average American eats in a day. As you can see, for example, oil,
is a high calorie density, meaning a high calorie concentration, lots
of calories packed into a small space, so drizzling just a tablespoon of oil onto
a dish adds over a hundred calories.
For those same calories, you
could have instead eaten about two cups of blackberries, for example,
a food with a low calorie density. So, these two meals have
the same number of calories. You could swig down that spoonful of oil and not even feel anything in your stomach, but eating a couple of cups of
berries could start to fill you up. That’s why yes, biochemically
a calorie is a calorie, but eating the same amount of
calories in different foods, can have different effects. The average human stomach can expand
to fit about four cups of food; so, a single stomachful of
strawberry ice cream, for example, could max out our caloric
intake for the entire day. For the same 2,000 calories, to
get those same 2,000 calories from strawberries themselves… you’d have to eat 44 cups of berries. That’s 11 stomachfuls. As delicious as berries are, I don’t
know if I could fill my stomach to bursting 11 times a day. Some foods are just impossible to overeat. They're so low in calorie
density, you just physically couldn’t eat enough to
even maintain your weight. In a lab, a calorie is a calorie,
but in life, far from it.
Traditional weight-loss diets
focus on decreasing portion size, but we know these “eat less”
approaches can leave people feeling hungry and unsatisfied. A more effective approach may be to
shift the emphasis from restriction to positive “eat more” messaging of
increasing intake of healthy, low-calorie-density foods, but
you don’t know, until you… put it to the test. Researchers in Hawaii tried putting
people on more of a traditional, Hawaiian diet with all the
plant foods they could eat, unlimited quantities of fruits,
vegetables, whole grains, beans. And, the study subjects lost an
average of 17 pounds in just 21 days. Calorie intake dropped by 40%, but not
because they were eating less food. They lost 17 pounds in three
weeks eating more food, in excess of four pounds a day.
How could that be? Because whole plant foods tend
to be so calorically dilute, you can stuff yourself without getting
the same kind of weight gain. They lost 17 pounds in three
weeks eating more food. That’s why in my upcoming
new book, How Not to Diet, which I am very excited
about, [clears throat], that’s why “Low in Calorie Density”
is on my list of the 17 ingredients for an ideal weight loss diet. As noted before, Americans appear to
average about three pounds of food a day. So, if you stuck with mostly these foods,
you can see how you can eat more food and still shed pounds. A landmark study set to be
published next month, found that even when presented with the
same number of calories, and the same salt, sugar,
fat, fiber and protein, processed foods led to weight gain,
two pounds gained over two weeks; and unprocessed foods led to weight loss,
two pounds down in the same two weeks.
Here’s one of their processed food meals… which is probably healthier, actually,
than what most people eat. Non-fat Greek yogurt, baked potato
chips, sugar-free diet lemonade with a turkey sandwich, has the
same number of calories as this what the unprocessed-meal-food
folks were eating, a kind of a southwest entrée salad
with black beans, avocados, nuts… that’s the calorie density effect. Same calories but there’s just more food, no wonder it satisfied their hunger. And they ended up four pounds lighter
in two weeks eating more food. So, how can you decrease the
calorie density of your diet? Well, just a quick peek at the two
extremes should suggest two methods: abandon added fats and
add abandoned vegetables.
Method number one: Covertly put
people on a relatively low-fat diet, and they tend to lose body
fat every day even though they can eat as much as they want. But if you instead give those
same people the same meals, but this time sneak in
enough extra fats and oils to change it to a high-fat diet,
they gain body fat every day. In fact, in a famous
prison experiment in Vermont, lean inmates were overfed up
to ten thousand calories a day to try to experimentally make them fat. This turned out to be
surprisingly difficult. Most starting dreading breakfast
and involuntarily threw it up. The researchers learned how difficult
it was to have people gain weight on purpose, unless…
you feed them lots of fat. To get prisoners to gain
30 pounds on a regular diet, it took about 140,000 excess calories
per certain amount of body surface area.
To get the same 30-pound weight gain
just by adding fat to their diets, all they had to do was feed them
about an extra 40,000 calories. When the extra calories were
in the form of straight fat, it took as many as a hundred
thousand fewer calories to gain the same amount of weight. A calorie is not a calorie—
it depends on what you eat. In this case, lowering
fat content effectively made up to 100,000 calories, disappear. That’s why “Low in Added Fat”
is on my list of ideal weight loss ingredients as well. There are, however,
two important exceptions. Processed foods with “reduced-fat
claims” are often so packed with sugar that they can have the same number of
calories as a higher fat product. SnackWell’s fat-free cookies,
for example, at 1700 calories per pound are as calorie-
dense as a cheese danish. The other exception to the
low-fat rule is that vegetables are so calorically dilute
that even a high-fat veggie dish, like some oily broccoli with garlic
sauce, tends to be less calorie dense overall, which brings us to the second
strategy for lowering calorie density: instead of sneaking out
fat, sneak in vegetables.
The biggest influence on calorie
density is not fat, but water content. Since water adds weight and
bulk without adding calories, the most calorie-dense foods and
the most calorie-dense diets tend to be those that are dry. Some vegetables, on the other hand,
are more than 95% water, and not just iceberg lettuce. Cucumbers, celery, turnips,
cooked napa cabbage, bok choy, summer squash, zucchini,
bean sprouts, and bamboo shoots can top out at 95% water. They’re basically just
water in vegetable form. A big bowl of water-rich
vegetables is practically just a big bowl of trapped water. The effect on calorie
density is so dramatic the food industry wants
in on the action. They figure they could use nanotechnology to “structure a solid processed
food similar to a celery stalk with self-assembled, water-filled,…
nanocells or nanotubes.” No need, as Mother Nature beat you to it. When dozens of common
foods, pitted head-to-head for their ability to
satiate appetites for hours, the characteristic most
predictive was not how little fat or how much protein it had,
but how much water it had.
That was the number one
predictor of how filling a food is. That’s why “High in Water-
Rich Foods” is on my list, too. Water-rich foods like
vegetables, topping the charts with most more than
90% water by weight, followed by most fresh fruit,
coming in around the 80s. Starchier vegetables, whole
grains, and canned beans are mostly 70s, meaning three-
quarters of their weight: pure water. In general, when it comes to water-
rich foods, most whole plant foods float towards the top, most animal
foods fall somewhere in the middle, and most processed foods
sink to the bottom. In a famous series of experiments,
researchers at Penn State University decided to put water-rich
vegetables to the test. Study subjects were served pasta and told to eat as much or
as little as they’d like, and on average, they consumed
about 900 calories of pasta. What do you think would happen if
as a first course, you gave them a hundred calories of
salad composed largely of lettuce, carrots, cucumber,
celery, and cherry tomatoes? Would they go on to eat
the same amount of pasta and end up with a thousand
calorie lunch, 900 plus 100? Or would they eat maybe a
hundred fewer calories of pasta, effectively canceling out
the added salad calories? It was even better than that.
They ate more than 200
fewer calories of pasta. Thanks to the salad, a hundred
calories in, 200 calories out. So, in essence, the salad
had negative 100 calories. Preloading with vegetables
can effectively subtract a hundred calories out of a meal. That’s how you can lose
weight by eating more food. Of course, the type of salad matters. The researchers repeated the experiment,
this time adding a fatty dressing, extra shredded cheese, which
quadrupled the salad’s calorie density. Now, eating this salad as
a first course didn’t turn a 900-calorie meal into one
with less than 800 calories. Instead, it turned it into a meal
with calories in the quadruple digits.
It’s like preloading
pizza with garlic bread— you could end up with
more calories overall. So, what’s the cut-off? Studies on preloading show that eating
about a cup of food before a meal decreases subsequent intake
by about 100 calories; so, to get a “negative calorie” effect,
the first course would have to contain fewer than a hundred
calories per cup. As you can see in the chart,
this includes most fresh fruit and vegetables, but having something
like a dinner roll wouldn’t work. But, hey, give people a large apple
to eat before that same pasta meal, and rather than consuming
two hundred calories less, it was more like three
hundred calories less, so…
How many calories
does an apple have? It depends on when you eat it. Before a meal, an apple could effectively
have about negative 200 calories. You can see the same thing giving
people vegetable soup as a first course. Hundreds of calories disappear. One study tracked people’s
intake throughout the day even found that overweight subjects
randomized to pre-lunch vegetable soup not only ate less lunch,
but deducted an extra bonus hundred calories at dinner,
too, a whole seven hours later. So, the next time you sit
down to a healthy soup, you can imagine calories being veritably sucked out of your body
with every spoonful. Even just drinking two cups of
water before a meal immediately caused people to cut about 20%
of calories out of the meal, taking in more than 100 fewer calories. No wonder overweight men and women
randomized to two cups of water before each meal lost
weight 44% faster.
Two cups of water before each
meal, 44% faster weight loss. That’s why so-called “Negative
Calorie Preloading” is on my list of weight loss boosters – which are
all the things I could find that can accelerate weight loss regardless
of what you eat the rest of the time. Negative calorie preloading just
means that starting a meal with foods containing less than a
hundred calories per cup.
That includes many fruits,
vegetables, soups, salads, or simply, a tall glass of water. Anything we can put on that first-course
salad to boost weight loss even further? In my “Amping AMPK” section I talk
about ways to activate an enzyme known as the “fat controller.” Its discovery is considered
one of the most important medical breakthroughs in
the last few decades. You can activate this enzyme through
exercise, fasting, and nicotine, but is there any way to boost it
for weight loss without sweat, hunger, or the whole dying-a-horrible-
death-from-lung-cancer thing? Well, Big Pharma is all over it. After all, obese individuals may be “unwilling to perform even a
minimum of physical activity,” wrote a group of pharmacologists,
“thus, indicating that drugs mimicking endurance exercise are highly desirable.” So, “it’s crucial that oral
compounds with high bioavailability are developed to safely induce
chronic AMPK activation” for “long-term weight
loss and maintenance…” But, there’s no need to develop such
a compound since you can already buy it at any grocery store.
It's called… vinegar. When vinegar—acetic acid—is
absorbed and metabolized, you get a natural AMPK boost.
Enough of a boost to lose weight at the typical dose you
might use dressing a salad? Vinegar has evidently been used
to treat obesity for centuries, but only recently has it been…
put to the test. Randomized, double-blind, placebo-
controlled trial on the effects of vinegar intake on the reduction of
body fat in overweight men and women. The subjects were randomized to
drink a daily beverage containing one or two tablespoons
of apple cider vinegar or a controlled beverage developed to
taste the same as the vinegar drink, but prepared with a different kind of acid so it didn’t have actual vinegar in it.
Three months in, the fake vinegar
group actually gained weight (as overweight people tend to do),
whereas the genuine vinegar groups significantly lost body fat,
as determined by CT scan. A little vinegar every day led to
pounds of weight loss achieved for just pennies a day without
removing anything from their diet. That’s why one of my 21 tweaks
to accelerate weight loss is… two teaspoons of vinegar with each
meal, either sprinkled on your salad or even just added to tea
with some lemon juice. The beauty of the vinegar studies is
that they were not just randomized, controlled trials, but
placebo-controlled trials.
Some studies aren’t controlled at all. Women asked to eat a ripe tomato
before lunch every day for a month lost about two pounds, but without
a control group you don’t know if the tomato had anything to do with it. Just being enrolled in a weight-
loss study where you know they’re going to come back
and weigh you in a month can have people change
their diets in other ways. I mean it’s certainly possible. A tomato is 95% water; so, you’d be filling up a fist-
sized portion of your stomach with only about fifteen calories before
a meal, so it’s certainly possible, but we’d need a better study
to prove it for weight loss. Stronger studies have control groups, at least, for example, randomize people to a weight-loss diet with or without
one to two cups of low-sodium vegetable juice, and those
drinking the vegetable juice lose significantly more weight.
Or split people into two groups and
give half about two tablespoons of goji berries a day,
and forty-five days later, the goji group appeared to cut two-and-
a-half inches off their waistline compared to no change
in the control group. But any time you have one
group do something special, you don’t know how much of the
benefit is due to the placebo effect. In drug trials it’s easy: you give
half the people the actual medication and the other half an identical-
looking sugar pill placebo.
Both groups are then doing the same
thing—taking identical-looking pills— and so, if you see any
difference in outcomes, we can suspect it’s the
due to the actual drug. But what would placebo
broccoli look like? That’s the problem. You can’t stuff cabbage into a
capsule, but there are some foods so potent that you could
actually fit them into a pill to pit them against placebos: spices. Want to know if garlic
can cause weight loss? Give people some garlic
powder compressed into tablets versus placebo pills and…
Garlic worked, resulting
in both a drop in weight and in waistlines within six weeks. They used about a half
teaspoon of garlic powder a day, which would cost less than four cents. Four cents too steep? How about two cents a day? A quarter teaspoon of
garlic powder a day, about a hundred overweight men
and women were randomized to a quarter teaspoon worth of
garlic powder a day or placebo, and those unknowingly taking the two
cents worth of garlic powder a day lost about six pounds of straight body
fat over the next fifteen weeks. Now if you can splurge up to three
cents a day, there’s black cumin. A meta-analysis of randomized,
controlled trials shows weight-loss efficacy again with just a
quarter teaspoon a day. Not regular cumin, this is a completely
different spice known as black cumin. What is black cumin? You obviously haven’t been
reading your bibles.
Described as a “miracle herb,”
besides the weight loss, there are randomized controlled trials
showing daily black cumin consumption significantly improves cholesterol
and triglycerides, significantly improves blood
pressure… and blood sugar control. But I use it, just cause it tastes good— I just put black cumin seeds in a
pepper grinder and grind it like pepper. With more than a thousand papers
published in the medical literature on black cumin, some reporting
extraordinary results like dropping cholesterol levels as much as a statin drug. Why don’t we hear more about it? Why weren’t we taught
about it in medical school? Presumably because there’s
no profit motive. Black cumin is just a
common, natural spice. You’re not going to thrill your
stockholders selling something that you can’t patent, that
costs three cents a day. Or you can use regular cumin, the second
most common popular spice on Earth.
Those randomized to half of a
teaspoon at both lunch and dinner over three-months lost four more
pounds and an extra inch off their waist, found comparable to the
obesity drug known as orlistat. That’s the “anal leakage” drug
you may have heard about, though the drug company evidently
prefers the term “fecal spotting” to describe the rectal discharge it causes.
The drug company’s website offers
some helpful tips, though, “it's probably a smart
idea to wear dark pants and bring a change of
clothes with you to work.” You know, just in case their drug causes
you to crap your pants at work. I think I’ll stick with the cumin. Cayenne pepper can counteract the
metabolic slowing that accompanies weight loss and accelerate
fat burning as a bonus. Ginger powder! Over a dozen randomized controlled trials starting at just a quarter
teaspoon of ground ginger a day, showing significantly decreased body
weight for just pennies a day. Proven in placebo-controlled trials to work, but you probably never heard
about any of this because they can’t
make enough profit. Don’t get me started. Let me go back to the
Coke versus carrots example. A calorie is not a calorie because drinking
this, is not the same as eating this. But even if you consumed
the same number of calories, chewed for hours to pack
in all those carrots, a calorie may still not be a
calorie, because it’s not what you eat, it’s what you absorb.
As anyone who’s ever eaten
corn can tell you, some bits of vegetable matter
can pass right through you. A calorie may still be a
calorie circling your toilet bowl, but flushed calories aren’t
going to make it onto your hips. That’s where fiber comes in. If you bump people’s fiber intake up, even to just the recommended minimum
daily intake, they start losing weight, because they experience about
a 10% drop in daily caloric intake. Why should more fiber
mean fewer calories? Well first, it adds bulk
without adding calories. Cold-pressed apple juice, for example,
is basically just apples minus fiber. And you could chug a bottle
of juice in a couple of seconds, but to get the same number of calories, you would have to eat about
five cups of apple slices. That’s the difference fiber can make, but
it’s not just a calorie density thing. Imagine what happens next: The apple
juice would get rapidly absorbed as soon as it spilled out of your stomach
into the gut, spike your blood sugars, whereas the sugar trapped in
the mass of chewed apple slices would be absorbed more slowly
along the length of your intestines.
Nutrients can only be absorbed when
they physically come in contact with the side of your
intestine, with your gut wall. Fiber never gets absorbed; so,
it can act as a carrier to dilute or even eliminate calories
out the other end. And fiber doesn’t just trap sugars. It acts as a fat- and
starch-blocker, too. Those on a Standard American Diet
lose about 5% of their calories through their waste every day, but
on a higher-fiber diet we double that.
It’s not what you eat,
but what you absorb; so, you can lose weight on a high-fiber
diet eating the exact same number of calories simply because some
of those calories get trapped, get flushed down the toilet, and
never make it into our system. And it’s not just the calories
in the high-fiber foods themselves that are less available. High-fiber foods trap
calories across the board. So, eat a Twinkie on a high-fiber diet
and you absorb fewer Twinkie calories. It’s like every calorie label you
look at gets instantly discounted when you're eating lots of fiber-rich foods, which is why it makes it onto my list. My section on other fat-blocking
foods starts out with a command to “Eat Your Thylakoids”, doctor’s orders. What on earth is a thylakoid? Just the source of
nearly all known life and… the oxygen we breathe. No biggie. Thylakoids are where
photosynthesis takes place, the process by which plants
turn light into food. Thylakoids are the great green
engine of life, microscopic sac-like structures composed of
chlorophyll-rich membranes concentrated in the
leaves of plants.
When we eat thylakoids, when we bite
into a leaf of spinach, or something, those green leaf membranes
don’t immediately get digested. They last for hours in our intestines
and that’s when they work their magic. Thylakoid membranes bind to lipase. Lipase is the enzyme that
our body uses to digest fat; so, you bind the enzyme –
you slow fat absorption. But if all the fat is eventually
absorbed, what’s the benefit? Location, location, location. There’s a phenomenon known
as the ileal brake. The ileum is the last part
of the small intestine before it dumps into your colon,
and when undigested calories are detected that far
down in your intestines, your body thinks “I must be
full from stem to stern,” and puts the brakes on eating
more by dialing down your appetite.
This can be shown experimentally. If you insert a nine-foot tube down
people’s throats and drip in any calories: fat, sugar, protein, and you
can activate the ileal brake. Sit them down to an all-you-can-eat
meal, and compared to the placebo group who had just gotten a squirt
of water down the tube, people eat about a hundred calories less. You just don’t feel as hungry. You feel just as full,
eating significantly less. That’s the ileal brake in action. This can then translate into weight loss. Randomize overweight women on a
diet to “green-plant membranes” (in other words, just covertly
slip them some powdered spinach), and they get a boost in appetite
suppressing hormones, a decreased urge for sweets. Yes indeed, spinach can cut
your urge for chocolate.
And boom, accelerated weight loss. All thanks to eating green, the actual green itself, the chlorophyll-
packed membranes in the leaves. Now, the researchers used spinach
powder just so they can create convincing placebos, but you
can get just as many thylakoids eating about half a cup of cooked
greens, which is what I recommend people eat two times a day in my Daily
Dozen checklist of all the healthiest of healthy things I encourage people
to fit into their daily routine.
In the Journal of the
Society of Chemical Industry, a group of food technologists argued
that given their fat-blocking benefits, “thylakoid membranes could be
incorporated in the functional foods as a new promising appetite-
reducing ingredient”— or you can just get them the
way Mother Nature intended. Which greens have the most? You can tell just by looking at them. Because thylakoids are where the
chlorophyll is, the greener the leaves, the more potent the effect. So, go for the darkest
green greens you can find. Where I shop that’s the
lacinato (a.k.a. dinosaur) kale. Now, if you overcook greens too long,
you know how they turn that drab olive brown, that’s the thylakoids physically degrading,
but blanched for fifteen seconds or so in steaming or boiling water, you know
greens get an even brighter green— that actually translates into a
boost in the fat-blocking ability.
So, you can gauge thylakoid
activity in the grocery store, in your kitchen with your own
two eyes by going for the green. Though thylakoids eventually
get broken down, fiber makes it all the
way down to our colon. While it’s technically true
that we can’t digest fiber, that’s only applicable to the
part of us that’s actually human. Most of the cells in
our body are bacteria. Our gut flora, which weigh as
much as one of our kidneys, are as metabolically active as our liver,
has been called our “forgotten organ,” and it’s an organ that runs on MAC,
Microbiota-Accessible Carbohydrates. So, when you see me write
“Eat Lots of Big MACs” I don’t want anyone to
get the wrong idea. MAC is just another name for prebiotics –
what our good gut flora eats, in other words… fiber. There’s that fiber again. What do our good bacteria
do with the fiber? We feed them and they feed us right back. They make short-chain fatty acids
that get absorbed from the colon into our bloodstream,
circulate through our body, and even make it up into our brain. That’s like the way our gut
flora communicates with us, dialing down our appetite,
all the while increasing the rate at which we burn fat and boosting
our metabolism at the same time.
All thanks to fiber. Check this out. Put people on a brain scanner and
show them a high-calorie food like a donut and the reward centers
in their brains instantly light up. But, if you repeat the
experiment, but this time, secretly deliver fiber-derived
short-chain fatty acids directly into their colon, you get
a blunted reward center response and subjects report that high-calorie
foods just seemed less appetizing, and subsequently ate less
of an all-you-can-eat meal. But fiber supplements
like Metamucil don’t work, which makes sense because
they're non fermentable, meaning our gut bacteria can’t eat them; so, yeah, they can improve bowel regularity, but can’t be used by our good bacteria to make those compounds
that can block our cravings.
For that, we have to
actually eat real food. Our good gut bugs are trying to help us,
but when we eat a diet deficient in fiber, we are in effect starving
our microbial self. Less than 5% of Americans reach
even the recommended minimum daily adequate intake of fiber, no surprise
since the number one sources are beans and whole grains, and
96% of Americans don’t even reach the recommended minimum
intake of legumes (which are beans, split
peas, chickpeas, and lentils), and 99% don’t reach the
recommended minimum for whole grains. Most people don’t even
know what fiber is. More than half of Americans
surveyed think that steak is a significant source of fiber. However, by definition, fiber
is only found in plants. There is zero fiber in meat,
eggs, or dairy, and typically little or no fiber in processed junk,
and therein lies the problem. But wouldn’t at least the
protein in that steak fill you up? Surprisingly, even a review supported
by the meat, dairy, and egg industries acknowledged that protein intake
does not actually translate into eating less later on, whereas you eat a fiber-rich whole grain for supper, and it can cut your calorie intake more than 12 hours later at lunch the next day! You feel full a hundred calories
quicker the following day because by then, your good
gut bugs are feasting on the same bounty and
dialing down your appetite.
Today, even our meat could
be considered junk food. For more than a century, one of the
great goals of animal agriculture has been to increase the carcass
fat content of farm animals. Take chicken, for example. A hundred years ago, the USDA
determined chicken was about 23% protein by weight
and less than 2% fat. Today, chickens have been
genetically manipulated through selective breeding to
have about ten times more fat. Chicken Little has become Chicken Big
and may be making us bigger too. Meat consumption in general is
associated with weight gain, but poultry appeared to be the worst.
Even just an ounce a day—which
is like a single chicken nugget, or like one chicken
breast every ten days, was associated with weight gain
compared to eating no chicken at all. You know, it’s funny, when the meat
industry funds obesity studies on chicken, they choose for
their head-to-head comparison, foods like “cookies and
sugar-coated chocolates.” This is a classic drug industry
trick to try to make your product look better by comparing
it to something worse.
Apparently, just regular chocolate wasn’t
enough to make chicken look better. But what happens when chicken is
pitted against a real control, like chicken without the actual chicken? Chicken chickens out. Both soy-based proteins and Quorn,
which is a plant-based meat made from the mushroom
kingdom, were found to have stronger satiating
qualities than chicken. Feed people a chicken and rice lunch,
and four-and-a-half hours later, they eat 18% more of a
dinner buffet than had they instead been given a chicken-
free chicken and rice lunch. These findings are consistent
with childhood obesity research that found that meat consumption
seemed to double the odds of school children becoming overweight, compared to the consumption
of plant-based meat products. Whole-food sources of plant protein
such as beans did even better though, associated with cutting in half
the odds of becoming overweight.
So, that’s why I consider these
kinds of plant-based meats more of a useful stepping stone
towards a healthier diet, rather than the end-game goal/ideal. Part of the reason plant-based
meats may be less fattening is they cause less of an insulin spike. A meat-free chicken like Quorn causes up to 41% less of an
immediate insulin reaction. It turns out animal protein
causes almost exactly as much insulin release as pure sugar. Just adding some egg whites to your
diet can increase insulin output as much as a 60% within four days. And fish may be even worse. Why would adding tuna to mashed
potatoes spike up insulin levels, but adding broccoli instead cut
the insulin response by about 40%? It’s not the fiber, since giving
the same amount of broccoli fiber alone provided no significant benefit. So, why does animal
protein make things worse but plant protein makes things better? Plant proteins tend to be lower
in the branched-chain amino acids which are associated with insulin
resistance, the cause of type 2 diabetes. You can show this experimentally. Give some vegans
branched-chain amino acids, and you can make them as
insulin resistant as omnivores. Or, take some omnivores and put them
even through a “48-hour vegan diet challenge,” and, within two days,
you can see the opposite— there's a significant improvement
in metabolic health.
Why? Because decreased consumption
of branched-chain amino acids improves metabolic health. Check this out. Those randomized to restrict their protein
intake were averaging literally hundreds more calories a day; so, they
should have become fatter right? But no, they actually
lost more body fat. Restricting their protein enabled
them to eat more calories, while at the same time
they lost more weight. More calories, yet a loss in body fat. And this magic “protein restriction”? They were just having people eat
the recommended amounts of protein. So, maybe they should have just called
this group the normal protein group, or the recommended protein group, and
the group that was eating more typical American protein levels
and suffering because of it, the excess protein group. Given the metabolic harms of excess
branched-chain amino acid exposure, leaders in the field have
suggested the invention of drugs to block their absorption, to
“promote metabolic health and treat diabetes and obesity without
reducing caloric intake.” Or, we can just try
not to eat so many branched-chain amino
acids in the first place.
They are found mostly in meat, including
chicken and fish, dairy products, and eggs, perhaps explaining why
animal protein is associated with higher diabetes risk, whereas
plant protein appears protective. So, defining the appropriate upper
limits of animal protein intake may offer a great chance for the prevention
of type 2 diabetes and obesity, but it need not be all or nothing. Even an intermittent vegan diet
has been shown to be beneficial. If there was one piece
of advice that sums up the recommendations in my
upcoming book it would be: “Wall Off Your Calories.” Animal cells are encased only
in easily digestible membranes, which allows the enzymes
in our gut to effortlessly liberate the calories in a steak, for example.
Plant cells, on the other hand, have
cell walls that are made out of fiber, which present an
indigestible physical barrier; so, many of the calories remain trapped. Now, processed plant foods, however,
fruit juice, sugar, refined grains, even whole grains if they have
been powdered into flour, have had their cellular structure
destroyed, their cell walls cracked open and their calories are free for the taking. But when you eat structurally
intact plant foods, chew all you want— you’re still going to end up with
calories completely surrounded by fiber, which then blunts the glycemic
impact, activates the ileal brake, and delivers sustenance
to your friendly flora. So, bottom line, try to make sure
as many of your calories as possible— your protein, your carbs, your fat—
are encased in cell walls, in other words from whole,
intact plant foods.
That’s what nature intended to happen. Millions of years before we learned how to sharpen spears and mill
grains and boil sugar cane, our entire physiology is presumed
to have evolved in the context of eating what the rest of our
great ape cousins eat: plants. The Paleolithic period, when
we started using tools, only goes back about
two million years. We and the great apes have been
evolving since back in the Miocene era, more like
twenty million years ago. So, for the first 90% of
our hominoid existence, our bodies evolved on mostly plants.
It’s no wonder then that
our bodies may thrive best on the diet we were designed to eat. So, maybe we should go
back to our roots. [clears throat] With enough portion control,
anyone can lose weight. Lock someone in a closet,
and you can force them to lose as much body fat as you want. Chaining someone to a treadmill
could probably have a similar effect. But what is the most
effective weight-loss regimen that doesn’t involve calorie
restriction or exercise—or a felony? I scoured through the
medical literature and all the randomized controlled trials,
and the single most successful strategy to date is a
diet of whole plant foods. The single most effective weight loss
intervention like that ever published in the peer-reviewed medical
literature, a whole food, plant-based diet. That works better than
anything else studied to date. And, no wonder given
what we just learned about fiber and branched-chain amino acids.
We’ve known for more than forty
years that those eating predominantly plant-based diets weigh, on average,
about thirty pounds less than the general population, but you
don’t know if it’s the diet itself… until you put it to the test. In 2017, a group of New Zealand
researchers published the BROAD study, a twelve-week randomized
controlled trial in the poorest region of the country with
the highest obesity rates. Overweight individuals were randomized
to receive either standard medical care or semi-weekly classes offering advice
and encouragement to eat a low-fat diet centered around fruits,
vegetables, whole grains, and legumes. And that’s all it was, just
empowerment, and information, empowerment with knowledge. No meals were provided, the
intervention group was merely informed about the benefits of plant-
based living and encouraged to fit it into their own lives at home.
No significant change in the control group,
but the plant-based intervention group, even though there were no restrictions
on portions and being able to eat freely all the healthy foods they wanted,
lost an average of nineteen pounds by the end of the three-month study. Nineteen pounds is a respectable
weight loss, but what happened next? At the end of those twelve
weeks, class was dismissed, and no more instruction was given. The researchers were curious to see how much weight the
subjects had gained back after being released from the study.
So, everyone was invited back at the six-month mark
to get re-weighed. The plant-based group had
left the three-month study nineteen pounds lighter on average. But, six months later
they were only down about… twenty-seven pounds! They got better. The plant-based group had been feeling
so good both physically and mentally… and had been able to come off
so many of their medications, that they were sticking
to the diet on their own and the weight continued to come off.
What about a year later? Even in studies that last a whole year, where people are coached to stay on a
particular diet for the entire years’ time, by the end of the year, any initial weight
lost typically tends to creep on back. The BROAD study only lasted three
months, yet after it was all over, those who had been randomized
to the plant-based group not only lost dozens of
pounds, but they kept it off. They not only achieved greater weight
loss at six and twelve months than any other comparable trial— that was months after the
study had already ended! A whole food, plant-based diet achieved the greatest weight loss ever recorded compared to any other such intervention
published in the scientific literature.
You can read the record-breaking
study yourself for free, in full, at nature.com/articles/nutd20173
or you can just point your phone camera up at
the screen and pick off the QR code. Any diet that results in reduced
calorie intake can result in weight loss. Dropping pounds isn’t
so much the issue. The problem is keeping them off. A key difference between
plant-based nutrition and more traditional approaches to weight
loss is that people are encouraged, on plant-based diets, to eat ad
libitum, meaning eat as much as they want.
No calorie counting, no
portion control—just eating. The strategy is to improve
the quality of the food rather than restricting the quantity of the food. If you put people on a diet packed
with fruits, vegetables, whole grains, and beans and allow them to
eat as much as they want, they end up eating about 50% fewer
calories than they might have otherwise. Just as full on half the calories. How can you keep people satisfied cutting more than a thousand
calories from their daily diet? By eating more high-bulk,
low-calorie-density foods (vegetables, fruits,
whole grains, and beans) and fewer calorie-dense foods,
like meats, cheeses, sugars, and fats. But it may not just be the
calories-in side of the equation; those eating more plant-based
appear to effectively be burning more calories in their sleep. The resting metabolic rate of
those eating more plant-based may be 10% higher, or more; a boosted
metabolism that can translate into burning off hundreds of extra calories
a day more without doing a thing.
Eating more plant-based you
burn more calories just existing. So, no wonder why those who eat
more plant-based tend to be slimmer. Start packing your diet with real
foods that grow out of the ground, and the pounds should come off naturally, taking you down towards your ideal weight. OK, so that’s what I spent the
first half of the book doing, laying out the optimum
weight-loss diet, “Plant Yourself.” Then I spend the second half of the
book on all the tools I unearthed to drive further weight loss for
any stubborn pounds that remain.
We already learned that a calorie
is not necessarily a calorie. A hundred calories of chickpeas
have a different impact than a hundred calories
of chicken or Chiclets, based on factors like
absorption and appetite, but in the second half I go
a step further and explore how even the exact same foods eaten
differently can have different effects. Even if you eat the same amount,
even if you absorb the same amount, a calorie may still not be a calorie.
It’s not only what we
eat, but how and when. Just to give you a taste, the exact
same number of calories at breakfast are significantly less fattening than
the same number of calories at dinner. What?! That’s just mind-blowing. Same calories, different weight loss. A diet with a bigger breakfast
causes more weight loss than the same diet with a bigger dinner. So, my recommendation to stop
eating after 7 PM is not just because, you know, I’m afraid people are mindlessly
snacking on the couch or something. The same snack at night
is literally more fattening than eating the exact same
snack during the daytime, all thanks to our circadian
rhythms, our “Chronobiology.” Something I spend a whole chapter on. Some of the sleep data is really crazy too. Overweight adults were
randomized to eight weeks of either a calorie-restricted
diet or the same diet combined with five days a week of just
one less hour of sleep a night.
Now, they ended up sleeping
an hour later on the weekends. So, overall, they just cut three
hours of sleep out of their week. Now, surely 3 hours a week of
sleep difference is not going to change how much
weight they lost, right? And on the scale that was true. But in the normal sleep group, 80% of the weight loss was fat, whereas in the group missing
just a few hours of sleep, it was the opposite, with 80%
of the loss being lean body mass. So, you snooze you lose—fat! A few hours of missed sleep seemed
to totally flip fat loss on its head, but just looking at the
scale you wouldn’t know it. It’s like when people fast. Stopping eating completely for a week or two can
cause more weight loss than just restricting your
calories, but paradoxically, it may actually lead to
less loss of body fat.
Wait, how can eating fewer
calories lead to less fat loss? Because during fasting your body
starts cannibalizing itself and burning your
own protein for fuel. The scale made it look as
though they were doing better when they were fasting, but the
reality is they were doing worse. They would have lost more body
fat if they had kept eating; they would have lost more
body fat, eating more calories. Short-term fasting can interfere
with body fat loss, not accelerate it, and you see the same
thing, with the keto diet. Body fat loss actually slows down
when you switch to a ketogenic diet. Just looking at the bathroom scale,
though, the keto diet seems like a smashing success, losing less than
a pound a week on a regular diet to boom—three-and-a-half pounds in
seven days after switching to keto, but what was happening inside their
bodies told a totally different story.
On the ketogenic diet, their rate of body
fat loss was slowed by more than half; so, most of what they
were losing was water, but they were also losing protein,
they were also losing lean mass. That may help explain why the
leg muscles of CrossFit trainees placed on a ketogenic diet can shrink
as much as 8% within two months. Of course, even if keto diets
worked, the point of weight loss is not to fit into a skinnier casket. People whose diets even
tend to trend that way appear to significantly
shorten their lives. On the other hand, even just drifting
in the direction of eating more healthy plant foods is
associated with living longer. Those going the other way, though,
those who start out more plant-based but then add meat to their
diet at least once a week not only appear to double or
triple their odds of diabetes, stroke, heart disease, and weight gain, but may also suffer an associated
3.6-year drop in life expectancy.
That’s going from no meat to
just once-a-week meat or more. Low-carb diets have been shown to impair artery function and worsen heart disease. Whereas, whole food, plant-
based diets have been shown to actually reverse heart
disease – that’s what Ornish used. So, what appears to be the most
effective weight-loss diet just so happens to be
the only diet ever proven to reverse heart disease
in the majority of patients. If my grandma didn’t
have to die like that, no one’s grandma has to die like that. If that’s all a plant-based diet
could do—reverse the number-one killer of men and women, shouldn’t that be the default diet until proven otherwise? And the fact that it can also be
so effective in treating, arresting, or reversing other leading
killers, like type 2 diabetes and high blood pressure,
would seem to make the case for plant-based eating
simply overwhelming.
Only one diet has ever
been shown to do all that: a diet centered around
whole plant foods. You don’t have to mortgage
your health to lose weight. The single healthiest
diet also appears to be the most effective diet for weight loss. After all, permanent weight loss
requires permanent dietary changes— healthier habits just have
to become a way of life. And if it’s going to be life-long,
you want it to lead to a long life. Thankfully, the single best
diet proven for weight loss may just so happen to be the
safest, cheapest way to eat, for the longest, healthiest life. Thank you. [Applause].
