How Not to Diet

by Michael Greger

One way researchers have switched people from a diet rich in saturated fat to a more Mediterranean diet is to swap out some meat and dairy for nuts and avocados.

In this way, they would be eating the same amount of fat and calories, but suddenly, they’d also be eating significantly more fiber.1466 In that case, when they lose more weight, how do you know it was the change...

in a study where saturated fat was swapped for the same amount of mostly olive oil, people lost five pounds of fat in a month.

Remember that thermic effect of food, the amount of energy spent digesting, absorbing, and storing a meal? Well, it apparently costs 28 percent more calories to process a meal containing walnuts and 23 percent more calories to process a meal containing olive oil than it does to process a meal with the same number of calories and fat but in the form of cheese and butter.1480

By the time the World Health Organization (WHO) attempted to release a similar report decades later, Big Sugar had graduated from name-calling to flexing its political muscle. The WHO report, entitled Diet, Nutrition and the Prevention of Chronic Disease, contained six fateful words: “limit the intake of free sugars” (meaning added sugars). Within days, the sugar industry led a vicious attack, culminating in a threat to get Congress to withdraw U.S. funding to the World Health Organization entirely1502—all because of those six words.

When asked why Michelle Obama’s childhood obesity programs in the United States should not be modeled around the world, a U.S. official responded that they might harm American exports.1505

Remarkably, the cost of packaging may outweigh the cost of ingredients in a cereal box by more than ten to one.1513

Denying evidence that sugars are harmful to health seems always to have been at the heart of the sugar industry’s defense.1514 When the evidence is undeniable, though—like the link between sugar and cavities1515—the industry switches from denial to deflection, such as trying to refocus attention away from restricting intake to finding a vaccine against tooth decay.

Sugar pushers bristled at the term empty calories,1521 asserting that the calories in sugar were “not empty but full of energy”—in other words, full of calories, of which we now get too many.

Put people on a sugar-free challenge for two weeks, removing all added sugars and artificial sweeteners, and by the end of the trial, up to 95 percent said “sweet foods and drinks tasted sweeter or too sweet, and … said moving forward they would use less or even no sugar.”1598 Most stopped craving sugar within the first week.

Food tastes good for the same reason sex feels good. We wouldn’t last very long as a species without both. Without pleasure centers and reward pathways in our brains incentivizing our efforts, we might not have sufficient drive to seek out either. Hunting and gathering take a lot of work. No surprise, then, that our appetites and food cravings are governed in part by the “feel good” messengers in our brains: dopamine (the “reward hormone”), serotonin (the “happiness hormone”), oxytocin (the “love hormone”),1599 endorphins (our own body’s natural opioids), and endocannabinoids (our bodies’ natural cannabis compounds—think of the “munchies” effect).1600

The longer we eat healthier foods, the better they taste.

The less fat we eat, the more sensitive to fat our tongues appear to become, which may translate into people spontaneously reducing their intakes of butter, meat, dairy, and eggs.1673 Salt may override this effect,1674 though, so it may be important to cut down on both simultaneously.

There have been times when someone happens to see me eating something simple like a sweet potato, and they look at me as if I’m some type of ascetic monk. “Good for you,” they might say, “but I could never eat that way.” They think I’m living a life of deprivation. Far from it. They don’t understand that a sweet potato really tastes good to me (and with a little sprinkle of cinnamon, it tastes even better!).

Natural foods as grown can be delicious, but only after you’ve escaped the numbing shackles of industry manipulations to deaden your senses. I realize the thought of eventually savoring something like corn on the cob without butter or salt may sound ridiculous to some. You won’t believe it until you try it out for yourself: Cut out processed foods for a few weeks, and you’ll be amazed how good healthy can taste.

Zucchini is even less calorie dense than broccoli. You could eat 100 cups of sliced zucchini a day and still lose weight.1700 The calories in cucumbers are so dilute you’d have to eat more than 150 cups a day to gain weight1701 and more than 250 cups of chopped kale.1702

In the Mediterranean, olive oil is often used to dress beans, vegetables, and salads, so olive oil consumption can be an indicator of a healthier, more traditional diet.

In a more modern context, just adding olive oil to food is associated with increased obesity risk,1730 so weight loss on a Mediterranean diet may be in spite of, not because of, the olive oil.1731

This brings up the second strategy for lowering dietary calorie density: instead of sneaking out fat, sneak in vegetables.

I encourage everyone to look for no-salt-added soup varieties or make your own. For more on soup, check out the Wall Off Your Calories section.

maternal animal protein intake during pregnancy (primarily from meat) appears to increase the risk their children will grow up overweight.1850

Every daily portion of meat intake during the third trimester was correlated with about an extra percent of body fat mass in their children by their sixteenth birthday, potentially increasing their risk of becoming obese later in life, and this appeared to be independent of how many calories they ate or how much they exercised.1851

If you continue to eat meat, your best choice would likely be wild game1853 (critically, felled with lead-free ammunition only).

Are grains in general the problem, or only refined grains? Observational studies in which people and their diets are followed over time have consistently shown whole-grain consumption not only to be neutral but even associated with better weight control.

Children who consumed more than one and a half servings of whole grains per day were found to have 40 percent lower odds of being obese compared with those who consumed less than one daily serving.1870 In adults, weight gain might be reduced over the long term as much as two pounds for each extra one-ounce increment in daily whole-grain consumption.

Only 6–8 percent of American adults follow my recommendation to eat at least three servings of whole grains a day,

high whole-grain consumers tend to be more physically active, smoke less, and consume more fruits and vegetables.

Whole grains were still found to be associated with better weight control.1874

There are lots of potential mechanisms by which whole grains might facilitate weight loss—higher fiber, lower calorie density, lower glycemic response, a slower eating rate due to more chewing1875—but you don’t know, of course, until you put it to the test.

If you feed people a whole-grain rye porridge for breakfast (like oatmeal, but with rolled rye instead of rolled oats), they report significantly prolonged satiety and lowered hunger and desire to eat for up to eight hours after consumption compared to having eaten the same number of calories of white bread.

taking your grain game up a notch and graduate from mere whole grains to intact whole grains, such as oat groats (also known as hull-less or hulled oats).

One of the most dramatic changes in our diets has been the skyrocketing intake of salt. For most of human existence, we were only getting the pinch of salt a day naturally found in whole foods.1902 Now, thanks mostly to processed foods, we’re exposed to ten times more than our bodies were meant to handle.

Impractical or not, we can shop for low-sodium options, eat out less, and stop adding salt in the kitchen and dining room.

While the monounsaturated fats concentrated in nuts, olives, and avocados appear more likely to be detoxified or safely stored away, the saturated fats concentrated in meat, dairy, and junk can create the toxic breakdown products in our muscle cells thought responsible for the development of insulin resistance.1950

The vegans were found to have significantly less fat trapped in their muscle cells, which can translate into less insulin resistance and lower insulin levels.1953

So can switching fats help with weight loss? Amazingly, Australian researchers found that even if you feed people about the same number of calories and the same amount of fat, but switch out meat and butterfat for olive oil, nuts, and avocados, you lose nearly six more pounds of fat in a single month.

In fact, those who eat meat have up to 50 percent higher insulin levels in their bloodstreams.1971,1972 Might that just be because they’re more sedentary or something?

Fish and poultry may be even worse than the egg whites.1976 Add about half a can of tuna to some spaghetti, and induce about a 70 percent higher insulin spike in diabetics.1977 Skinless chicken breast and white rice cause an insulin reaction closer to straight sugar than rice alone.

Compared to chicken, the meat-free tastes-like-chicken Quorn causes up to 41 percent less of an insulin reaction within fifteen minutes.1979

put people on a plant-based diet and a modest, mostly walking-based exercise program, and within three weeks, their bad cholesterol can drop 20 percent and their insulin levels can plummet 30 percent, despite a 75–80 percent carbohydrate diet.1986 In contrast, the paleo diet appeared to have “negated the positive effects of exercise.”

BCAAs may explain why those randomized to a plant-based diet eliminate significantly more of the deeper, more dangerous fat, even when taking in the same number of calories.2022

even “intermittently substituting vegan meals in otherwise animal-based diets” may be beneficial in this regard.2028

Despite being rich in protein and starch, the insulin index of legumes, such as beans, split peas, chickpeas, and lentils, appears to parallel their very low glycemic index.2032

to reduce insulin levels to potentially facilitate weight loss: Rule #1: Avoid high-glycemic foods; Rule #2: Make plant protein your preference; and Rule #3: When you do eat animal protein, try to pay particular attention to Rule #1.

The human colon has been considered the most biodense ecosystem in the world, meaning there’s more life concentrated in our colons than anywhere else on Earth.2043 Many probably think that stool is composed primarily of undigested food, but most of it—about 75 percent—is pure bacteria.2044 Trillions and trillions of them—about half a trillion per teaspoon, in fact.2045 We are bacteria factories.

As Neil deGrasse Tyson put it, “More bacteria live and work in one linear centimeter of your lower colon than all the humans who have ever lived.”2046

This may help explain why children born by C-section have a 33 percent greater risk of childhood obesity.

Prevotella are linked to constituents found almost exclusively in plant foods.2092 Prevotella are fiber-feeders and pump out more short-chain fatty acids.2093

Native Africans who eat largely plant-based diets tend to have a Prevotella enterotype, while African Americans eating a typical Western diet tend to be in the Bacteroides camp. This may help explain why African Americans have fifty times more colon cancer, since short-chain fatty acids don’t just protect against obesity but have anticancer properties as well.2094 The question then becomes: How long does it take to shift your gut flora from one enterotype to the other?

What’s the absolute fastest you can change your microbiome? Researchers came up with diets from both extremes to find out: a plant-based diet rich in grains, beans, fruits, and vegetables, and an “animal-based” diet composed of meats, eggs, and cheeses.