How Not to Diet (Ever Again)
Half-truths and cherry-picked research fuel the diet industry. Dr. Michael Greger’s new book explodes the myths and surfaces the facts
Five years ago, nutrition expert Michael Greger, MD, distilled thousands of scientific studies into what became a New York Times bestselling tome — How Not to Die — describing how to eat to prevent the top 15 causes of premature death in America. Now, Dr. Greger, the physician behind the nonprofit website nutritionfacts.org, has done the same thing with the vast body of weight loss literature in his new book, How Not to Diet.
Ever since watching his grandmother reverse what was thought to be end-stage heart disease by adopting the low-fat Pritikin diet, Dr. Greger has made it his life’s mission to uncover — and educate people about — the disease-fighting, health-enhancing powers of food. Dr. Greger professes to “hate diet books,” which he says tend to rely on anecdotes and cherry-picked studies to back their claims. His new book offers more than 500 pages of science-backed weight loss strategies — along with the medical evidence to back them up. Here, Dr. Greger talks to CoveyClub about the key ingredients of the ideal weight-loss diet, and why replacing “dieting” with a healthy, sustainable way of plant-based eating may be the best strategy of all.
TheCovey: You say in the introduction to How Not To Diet that the entire diet industry is built upon a foundation of fake news. Can you explain?
Dr. Greger: The whole weight loss industry is so corrupted by financial interests that you don’t know who to trust. They feed us this endless parade of quick-fix fads — repeat customers is the whole industry model. Too often in diet books, the rule is to obfuscate rather than illuminate, and to cherry-pick study results to push some pet theory and ignore the rest. It’s the opposite of science.
TheCovey: There’s an overwhelming amount of nutritional advice in this book. If you wanted to start by making one dietary change, what should it be?
Dr. Greger: How about eating dark green leafy vegetables, the food with the lowest calorie density, that also has the fat-blocking structures called thylakoids that bind to your fat-digesting enzyme, lipase, slow food absorption, and dial down your appetite? Eat half a cup of cooked spinach, and half hour later, your urge for sweets dissipates. Put people in front of an all-you-can-eat buffet after they eat spinach and they eat significantly less. Do that day after day, and studies show they lose significantly more weight compared to control groups.
TheCovey: You culled through thousands of research articles investigating the question of whether it’s better to eat breakfast or skip it. What’s the verdict?
Dr. Greger: Eat breakfast! The more we can front-load the calories the better. Food eaten at night is more fattening than the exact food eaten in the morning. We should not only eat breakfast, but we shouldn’t eat after 7 pm. The fewer calories after sundown the better.
TheCovey: How can we best cultivate a healthy microbiome — and how can this help us to shed pounds?
Dr. Greger: By eating lots of prebiotics. That’s resistant starch and fiber found only one place in abundance: whole plant foods, particularly whole intact grains and legumes like beans, split peas, chickpeas and lentils. Because when we feed our good bacteria, they feed us right back with short chain fatty acids that get absorbed in our blood stream and circulated through our body and up into our brain, which is the way our good gut bugs communicate with us and dial down our appetite. Fiber-rich foods help via a variety of mechanisms, but fecal transplant studies prove that our gut bacteria play a critical role. If you take the gut microbiome of someone who is obese and transplant it into a skinny person, they gain weight, because we’ve switched out their bugs.
TheCovey: You devote an entire section of the book to weight-loss boosters, revealing surprising findings about everything from widely-used culinary spices like cumin to vinegar. What are some of the simplest adjustments — or additions — you can make to your diet to boost weight loss?
Dr. Greger: Negative calorie pre-loading, or starting out a meal with fruits, vegetables, soup — anything with less than 100 calories per cup. So, for example, eating a large apple before a meal is so filling that people go on to have 300 less calories at their meal. That’s 100 calories in a large apple, and eating 300 calories less, so an apple before a meal basically has 200 negative calories.
Incorporate vinegar into your meals by always having a side salad or even adding it to tea with some lemon juice. Add cumin to hummus or mix black cumin with the black peppercorns in the pepper grinder. Vinegar has been shown to reduce visceral fat, reduce blood sugar and increase satiety. Cumin acts as an appetite suppressant: Over three months, those randomized in studies to a half a teaspoon before lunch and dinner lost an average of four more pounds and an extra inch off their waist. And black cumin (also known as nigella) has been found to improve cholesterol, triglycerides, blood pressure and blood sugar control. The side effects? Loss of appetite and weight loss.
TheCovey: You suggest in your book that it’s not only what we eat, but how and when. How might we manipulate our metabolism through chronobiology?
Dr. Greger: By eating earlier in the day when appetite is less and calories don’t count as much. Everything is better in the morning in terms of our metabolism, including how we process blood sugar, so we shouldn’t eat at night. Front-load early in the day, and if you are skipping any meal, like with intermittent fasting, skip dinner, not breakfast. Also, it’s critical to not only get enough sleep, but regular sleep. We shouldn’t sleep in on weekends, and we should get at least seven hours of sleep, seven days per week. We should ideally exercise before meals to enhance our loss of body fat: You burn significantly more fat by exercising beforehand. But that’s only for nondiabetics. Diabetics should exercise after meals.
TheCovey: Can you explain what you mean when you write “It’s not what you eat but what you absorb”? How can a high-fiber diet help you to lose more weight?
Dr. Greger: So there’s this concept put forth by the food industry to try to absolve itself of culpability, that a calorie is a calorie, that a calorie from one source is the same as a calorie from another. And it’s just not true. It’s not what you eat but what you absorb. High-fiber food traps calories from both those foods themselves and anything else you eat. It gets trapped in that mass of fiber as it goes through your system, so you’re pooping out those calories instead of storing them.
TheCovey: You talk about how by eating more anti-inflammatory foods and fewer inflammatory foods, we may be able to prevent and treat damage to the appetite-regulating apparatus in our brains. Can you explain how this works, and give me examples of foods to seek out and avoid to reap these benefits?
Dr. Greger: Just as if we get too hot, we sweat, and if we get too cool, we shiver, our body also has a natural thermostat so that when we get too skinny, our appetite revs up, and if we get too fat, we dial down our appetite. So why do we have an obesity epidemic? Our brain becomes resistant to the appetite-regulating hormone, leptin, produced by fat cells. When we gain weight, our leptin levels go up, and signal to the brain that we need to stop eating. But our brain becomes resistant to that signal. What causes you to become leptin resistant is damage to the circuits in your brain. Saturated fats found in meat, dairy and processed junk: Those are pro-inflammatory foods, which do damage to our brain — and that damage can be reversed if you eat healthily. Pro-inflammatory foods would be anything high in saturated fats, trans fats, and dietary cholesterol. Anti-inflammatory foods are fiber-rich foods and polyphenol-rich foods: brightly colored fruits and vegetables like berries, greens, turmeric, and ginger.
TheCovey: How do we “reset our taste thermostats,” as you say, so that we begin to find healthy foods more appealing than unhealthy ones?
Dr. Greger: The more you eat healthy foods, the better they taste. You start preferring low-salt and low-sugar foods. Natural foods taste delicious, but even the ripest peach would taste sour after a bowl of Froot Loops. We just have to move away from hyper-sweet and hyper-salty food. Stick with it until your taste buds change. This can happen within a number of weeks, maybe quicker if you cut out added sugars; that’s the exciting news.
TheCovey: How does what you call “choice architecture” help you resist being tempted by unhealthy foods?
Dr. Greger: It’s more of a social scientist approach to basically make healthy foods a default option. People tend to be mindless and go for the easy option. Have no junk in the house. If you have no junk in the house and you get hungry enough, eventually you’ll eat that apple. Twinkies still exist at the gas station, but you have to get in the car and drive there. Have a bowl of fruit out on the table and the snacks and crappy foods tucked away in the pantry so you aren’t staring at them all the time. Make it easy as possible to eat healthy and so that you have to actually work a little bit to eat unhealthily.
TheCovey: I found it interesting that the textures of food contribute to their effect on weight loss. Why should we choose bulkier, harder, chewier foods?
Dr. Greger: Because of oral sensory sensation. The longer we have sensations of eating in our mouths, the more the satiety signals go from our mouths to our brains telling us to stop eating. If you slip a tube down people’s throats and put food directly into their stomachs, their brains don’t get those signals. Modern food is designed to be eaten very rapidly — with liquid calories like soda pop you can eat 70 calories a minute. You can wipe out a whole hour at the gym, having burned 350 calories, by five minutes of snacking. It’s no wonder people are so obese. Make your oatmeal extra chewy — use steel cut oats, or even better, oat groats. Or make your smoothie thick and drink it with a thin straw. Anything that gets you to slow down. There’s a 20-minute rule: It takes your brain 20 minutes to register that you are eating, so make it last at least that long. Experiments show that you can cut down on total intake by increasing that oral sensory exposure time.
TheCovey: So can you explain why soup trumps solid food, but whole food trumps smoothies and fruit juices?
Dr. Greger: When you eat soup, you tend to eat a little bit at a time. If you have people drink their cold soup, you don’t have any benefit. But if you have people sip it with a spoon, it’s one of the slowest foods people eat, and your body has time to register that you are eating. Smaller spoons are better than large, and if the soup has some chewiness, for example, if it contains chunky vegetables, it is better than cream soup, because it takes longer for you to eat it.
TheCovey: In How Not to Diet, you introduce the reader to specific foods that double as fat blockers, fat burners, and appetite suppressants. Which foods top the greatest hits list in these categories?
Dr. Greger: You can find these in my Twenty-one Tweaks.* Vinegar, which amps AMPK, the molecule that flips the switch in your body from storing fat to burning fat, is the fat burner. In terms of fat blocking, probably thylakoids found in green leafy vegetables. Starch blockers would be beans, and metabolic boosters would be plain water, and spices like cayenne pepper, ginger powder, cumin, black cumin and saffron.
TheCovey: Why do you call a whole food, plant-based diet a “best-of-both-worlds eating pattern”?
Dr. Greger: It’s the most effective weight loss regimen ever published in the weight loss literature that doesn’t enforce exercise or calorie restriction. And, it just so happens to be the only diet ever proven to reverse — in the majority of patients — heart disease, the number one killer of men and women. You get the dual benefit of weight loss efficacy and health sustainability.
*You can find Dr. Greger’s “Twenty-one Tweaks” to accelerate weight loss in his book or on his free Daily Dozen mobile app. (The app’s name refers to the 12 things he says everyone should strive to fit into their daily routine for optimal health and longevity.)