In his book, How Not to Diet (Flatiron Books, 2019) and its companion, The How Not to Diet Cookbook (Flatiron Books, 2020), Michael Greger, M.D., of Nutritionfacts.org shares science-based lifestyle changes for long-term, sustainable weight loss. We caught up with him to learn more.
LN: What was your inspiration to write this book?
Dr. Greger: Obesity is not some moral failing. The battle of the bulge is a battle against biology. We’re living in a toxic food environment, floating and drowning in a sea of excess calories, while being bombarded with ads for fast food and candy. Becoming overweight is a normal, natural response to the abnormal, unnatural ubiquity of sugary, fatty foods that are concentrated with calories.
But, the weight loss industry is so corrupted by financial and ideological conflicts of interest that you can never know who to trust. Too often in diet books, the rule is to obfuscate rather than illuminate, to cherry-pick facts to push some pet theory and ignore the rest to promote your own agenda. It’s the opposite of science. In true scholarship, your conclusions follow from the evidence, not the other way around.
There’s so much nutritional nonsense that comes out of the diet industry, feeding us an endless parade of quick-fix fads that always sell because they always fail. Repeat customers are their whole business model, yet people just line right back up to be fooled again.
I just wanted there to finally be an evidence-based diet book. In my book, I cite literally thousands of studies, digging up every possible tip, trick, tweak and technique proven to accelerate the loss of body fat to give people every possible advantage and basically build the optimal weight-loss solution from the ground up.
LN: You note in your intro that this book is a novel method to eliminate body fat. Please explain.
Dr. Greger: Diets don’t work almost by definition. Going on a diet implies that, at some point, you will go off the diet. Short-term fixes are no match for long-term problems. Lifelong weight control requires lifelong lifestyle changes. It’s not what you eat today or tomorrow that matters, but what you eat over the next months and years, so you have to find lifestyle changes that fit into your lifestyle.
A diet has to be sustainable. Consider water-only fasting. No diet works better. It’s 100 percent effective, but also 100 percent fatal if you stick with it. An optimal diet also needs to be safe. Books touting liquid protein diets in the 1970s sold millions of copies, but the diets started killing people. Safety is about losing weight without losing your health.
Any long-term eating pattern must also be nutritionally complete and life-extending. In the very least, what we eat shouldn’t shorten our lives and ideally should be healthy enough to improve our life spans. Why lose weight if it causes you to lose it all?
How Not to Diet’s eating program is effective in achieving weight loss, but it’s so much more. Compared to more traditional approaches to dieting, plant-based nutrition encourages you to eat ad libitum, which means you can eat as much as you want. No calorie counting, no portion control. The primary strategy is to improve the quality of food rather than restricting the quantity of food.
The novel weight-loss strategy—experiment with mild Trendelenburg—has a number of caveats and contradictions, so it’s best that people read the entire section and make up their own mind if the purported benefits outweigh the risks and inconvenience.
LN: Why do you feel plant-based eating is such an important component of good health?
Dr. Greger: 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.
I took a deep dive into the medical literature for an answer to the obesity epidemic and not only did I succeed in finding a plain solution to the crisis, I also discovered the same solution that helped my dear grandmother after she had been given a medical death sentence and cured her of end-stage heart disease: a diet centered around whole plant foods.
We should eat natural foods that come from the ground and from the fields, not factories, and from gardens, not garbage. The very diet I discussed in my previous book, How Not to Die—the diet that has been proven to prevent, treat and even reverse some of our leading killer diseases—just so happens to be the same one with the greatest potential for achieving and maintaining permanent weight loss.
An effective weight-loss diet is an anti-inflammatory one, given the role we now know that inflammatory damage to the appetite-regulating circuits in our brains is playing. It’s a diet free of habit-forming ultra-processed foods and free of “obesogenic pollutants,” endocrine-disrupting chemicals in certain foods and plastics that can affect our hormonal balance. A diet that is high in fiber-rich foods that trap and dilute calories and flush them out the other end; a diet low in added fat, sugar, meat, salt and refined grains; a diet low in calorie density—some foods just have more calories per cup, per pound, per mouthful than others. Low Glycemic Load, Low Insulin Index, rich in prebiotics to cultivate a slimming microbiome. Each of these factors alone can help—like just cutting down on added sugars—but by putting them all together by eating more real food that grows out of the ground, the pounds should come off naturally.
LN: You came up with a list of 21 weight-loss accelerators, “an arsenal of weapons in your fight against fat” you write. How best can someone reading your book decide which of these to aim to incorporate into their lifestyle?
Dr. Greger: The Twenty-One Tweaks are my favorite part of How Not to Diet where I unveil all the fast-tracking weight-loss tricks I’ve found scouring the medical literature—all the ways in which any diet can be modified to maximize the loss of body fat.
On any given day, aim to hit all of the booster boxes—or none. A healthy diet, as encapsulated by the Daily Dozen in my previous book, How Not to Die, should be all you need to lose as much weight as you want, but the more of these extra Twenty-One Tweaks you can hit, the more successful you may be.
Of the Twenty-One Tweaks, my top three are preload with water, preload with “negative calorie” foods and fast after 7:00 p.m. So, drink two cups of metabolism-boosting cool or cold unflavored water before each meal and enjoy an apple or a Green Light soup or salad containing fewer than 100 calories per cup as a first course. And, since food eaten at night is more fattening than the exact same food eaten earlier in the day, due to our circadian rhythms, fast every night for at least 12 hours starting before 7:00 p.m.
Start experimenting with the weight-loss accelerators and see which ones work for you. The Twenty-One Tweaks give you a broad palette of tools to choose from, so find out which ones you can incorporate into your daily routine for the long term.
LN: Please discuss the benefits of your “21 Tweaks.” Would this be a good place for people to start on a path to healthy weight loss?
Dr. Greger: My goal with the Twenty-One Tweaks was to provide you with a simple daily checklist to make it easy for you to pick your own portfolio of techniques to attack excess body fat from multiple fronts. They’re boosters to accelerate weight loss.
The best way to start on a path to healthy eating and healthy weight loss is to wall off your calories. Animal cells are encased only in easily digestible membranes, which allow the enzymes in our gut to effortlessly liberate the calories within a chicken breast, for example. Plant cells, on the other hand, have cell walls that are made out of fiber, which acts as an indigestible physical barrier, so many of the calories remain trapped.
Processed plant foods, however, like fruit juice, sugar, refined grains and even whole grains if they’ve been powdered into flour, have had their cellular structure destroyed and their cell walls cracked open, so their calories are free for the taking. When you eat structurally intact plant foods, though, you can chew all you want but you’ll still end up with calories completely encapsulated by fiber, which then blunts the glycemic impact, activates what’s called the ileal brake that dials down appetite, and delivers sustenance to your friendly flora.
So, the bottom line is to try to make sure as many of your calories—whether from protein, carbs or fat—are encased in cell walls. In other words, from whole, intact plant foods.
LN: What is your opinion on additional supplementation beyond food?
Dr. Greger: Mother Nature’s powers cannot be stuffed into a pill or extracted and isolated. Plant foods are so wonderfully complex with synergistic effects that the whole can be greater than the sum of its parts. What’s more, the supplement industry is so poorly regulated, you never know what you’re getting. Even if supplements are labeled accurately, the fillers may bind to the active components and reduce bioavailability, or the capsule shell may not disintegrate properly.
Rather than popping pills or swallowing supplements, we should eat real food that grows out of the ground, natural foods that come from fields, not factories, gardens not garbage. A whole-food, plant-based diet was found to be the single most effective weight-loss intervention ever published in the medical literature, proven in a randomized controlled trial with no portion control, no calorie counting, no exercise component.
Despite being the healthiest eating pattern, an exclusively plant-based diet lacks vitamin B12, which is not made by plants, but by microbes blanketing the earth. In our sanitized modern world, we now chlorinate the water supply to kill off bacteria. Also, although we evolved to make all the vitamin D we need from the sun, most of us are inside during the day, rather than running around in equatorial Africa. So, I recommend a regular, reliable source of B12: for those up to 65 years old, 2,000 mcg (μg) vitamin B12 (cyanocobalamin) at least once a week (or 50 mcg a day), and up to 1,000 mcg daily if over 65. I also recommend those unable to get sufficient sun take one 2,000 IU vitamin D3 supplement daily, ideally with the largest meal of the day.