If obesity researchers are so smart, why are we so large? That's the question at the heart of Gary Taubes's new book, Why We Get Fat--and What to Do About It. After all, public health authorities have been hammering home a very simple message for the past 40 years: If you don't want to be fat, cut the fat from your diet. And in those years, obesity rates have gone from 13 percent to 22 percent to, in the last national survey, 33 percent.
Taubes thinks he knows why: Obesity experts have gotten things just about completely backward. If you look carefully at the research, he says, fat isn't the enemy; easily digested carbohydrates are. The very foods that we've been sold as diet staples--fat-free yogurt, plain baked potatoes (hold the butter), and plain pasta (hold the olive oil, sauce, and cheese)--actually reset our physiology to make us pack on the pounds. And the foods that we've been told to shun--steak, burgers, cheese, even the sour cream so carefully scraped from that potato--can help us finally lose the weight and keep our hearts healthy.
As you might imagine, Taubes has stirred controversy with his contentions. (Though he's known as an obsessive reporter and a science nerd ) he studied applied physics at Harvard and aerospace engineering at Stanford and has won numerous science-writing awards), he's been called a dangerous cherry picker of data--someone who searches through decades of studies to weave together the bits he likes. But a series of studies in the past five years has compelled researchers to rethink their long-held prejudices against low-carb diets. These days, scientists like Mitchell Lazar, MD, who directs the diabetes institute at the University of Pennsylvania, and cardiologist Allan Sniderman, MD, at McGill University, take Taubes's argument very seriously.
Here's what he wants you to know:
THE OBESITY EXPERTS ARE WRONG: "There's this absolutely fundamental idea when it comes to weight and obesity--that the way we get fat is that we take in more calories than we expend. It's the gluttony and sloth hypothesis: We eat too much and exercise too little. It sounds undeniable, as commonsensical as can be, and it's actually nonsense--it doesn't tell anything meaningful about why we get fat. If I get fatter, it's obvious that I must have overeaten. But if you ask the question, Why did you overeat? Well, that question I can't answer--not with the calories-in/calories-out theory of weight gain.
"People react to this as though I'm questioning the laws of thermodynamics. I'm not questioning them; I'm saying they're not relevant. Yes, if you're getting fatter, you're taking in more calories that you're burning--the question is why. There's a ridiculously simple alternative hypothesis, which is that you don't get fat because you're overeating. You overeat because you've developed a disorder in the way your fat tissue is regulated."
DIETS DON'T WORK
"Over the past 40 years, studies have shown that you can't get clinically significant effect from cutting calories. At the same time that experts are saying that gluttony and sloth are responsible for weight gain, they'll tell you that we know no diet works, and that's why we have to come up with some anti-obesity drug that'll make billions. That's why the medical community considers bariatric surgery--actually altering your digestive system--a reasonable solution."
"It shouldn't be a surprise that diets don't work. Obese people have spent their lives trying to eat less. There are probably a few people who gave up early and said, This is hopeless and I'm going to have a good time. But for the most part, you can define an obese person as someone for whom eating less didn't work. So the simple fact that a doctor tells you to eat less--how much good is that going to do?"
"If you cut calories, you'll be hungry all the time--that's a given. But what also happens is that you adjust your energy expenditure to match your reduced intake. Studies in animals show that if you restrict energy intake, their cells actually burn less energy, which is one reason that obesity researchers, in their honest moments, acknowledge that restricting calories is ineffective."
IT'S IMPOSSIBLE TO COUNT CALORIES
"Public health authorities want us to practice 'energy balance', which is a new way to say that you shouldn't take in more calories than you expend. So what does energy balance entail?"
"If you consume about 2,700 calories a day, which is typical if you average men and women together, that's a million calories a year, or ten million calories in a decade. Over the course of a decade, you're eating roughly ten tens of food. How accurately do you have to match calories-in to calories-out so that you don't gain more than 20 pounds over the course of a decade? Because if you gain 20 pounds every decade, you'll go from being lean in your 20s to obese in your 40s, which many of us do. And the answer is: 20 calories a day and put it into your fat tissue, you will gain 20 pounds every decade."
"The point is, nobody can match calories-in to calories-out with that kind of precision. Twenty calories is like a single bite of a McDonald's hamburger. It's a couple of sips of Coca-Cola or a few bites of an apple. No matter how good you are at counting calories, you can't do it. So if practicing energy balance is really the way to keep from getting fat, the question is, Why aren't we all fat?"
EXERCISING WON'T KEEP YOU THIN
"People in nutrition are so keen on making us lose weight by exercising that they've forgotten the fact that the more energy you expend, the hungrier you get. Imagine I asked Alice Waters, the great chef from Chez Panisse, to my house to make a 12-course feast, and you're invited. And I've got a pastry chef coming and a gourmet butcher--in Berkeley they have gourmet butchers now. Bring your appetite!!"
"The two things you're likely to do are that you might skip lunch, and you might exercise more. You might even say, Look, Taubes lives three miles from my house--I'm going to walk there, and by the time I get there, I'm going to be hungry. The joke is that the two things we tell people to do in order to lose weight--eat less and exercise more--are the exact two things you would naturally do if you wanted to make yourself hungry."
"When you look at the data from research on obesity and exercise, there's no compelling evidence that exercise has any effect on weight. The American College of Sports Medicine says in its guidelines, which were issued jointly with the American Heart Association, that it's reasonable to assume that if you exercise more, you'll be less likely to gain weight over time. But in those same guidelines, it also says that so far, data to support this hypothesis are not particularly compelling. Which is the kiss of death. It's a 100-year-old hypothesis--if the data aren't compelling by now, you can be pretty confident that the hypothesis is wrong."
BUT THERE IS A WAY TO LOSE WEIGHT
"Our mothers grew up believing refined carbohydrates and starches were fattening--pasta, potatoes, bread, sweets, rice, and corn. And they were right: These foods literally make you fat. Sweets are probably the worst, along with sugar-water combinations, which can be anything from fruit juice to Coca-Cola. The reason is that refined carbohydrates raise your insulin levels. Scientists have known since the early 1960s that insulin is the primary hormone that regulates your fat tissue. This is not controversial--if you go to an endocrinology textbook and look up what makes a fat cell fat, it'll tell you all the ways insulin does it. Then you look up obesity, and it'll say people get fat because they eat too much and exercise too little. There's a complete disconnect between the fundamental science and the cause of human obesity."
"All I'm saying to obesity researchers is, Pay attention to the hormonal and enzymatic regulation of the fat tissue. If you do, you'll get a different answer for what causes obesity and what cures it. Basically, Dr. Atkins got it right with the Atkins diet, although he didn't get all the science right."
YOU NEED TO EAT FOODS THAT KEEP INSULIN LOW
"We tend to think of our fat cells as a long-term bank account, where your body stores excess calories as fatty acids, which you don't use until you're starving. But the reality is that your fat tissue is more like your wallet, and your meals are like going to the ATM. You know how you use the ATM: You put the cash in your wallet and gradually spend it, and when you get too low, you go back to the ATM. But insulin locks the money in your wallet, so you've got to keep going back to the ATM. Your fat cells are getting fatter and fatter, but you can't get at the fatty acids that are stored inside them. So you get hungry and you eat again."
A LOW-CARB DIET IS KEY
"When I was first getting into this subject, I tried the Atkins diet as an experiment. It had never crossed my mind to do that--I associated it with quackery. But now I would go to a restaurant with friends, and they would get skinless chicken breast with green salad, and I would get a pepperoni and melted mozzarella cheese appetizer and a steak. The weight just dropped off. If I walked down the street, it was like you could see the pounds lying behind me on the sidewalk."
"I eat eggs and bacon or sausage for breakfast every day. At lunch, I might have three quarters of a pound of hamburger with cheese, no bun. Dinner is a pound of steak or half a roast chicken or the largest piece of fish I can buy, and vegetables. You eat what you want until you're satiated--you just don't eat the things that will make you fat."
"You go on this diet and eat breakfast, and suddenly it's two o'clock and you're thinking, Oh, I really should eat lunch. But you're not hungry. I used to eat a very low-fat diet, and I was hungry every two hours or so. And I gained weight every year."
"The biggest study so far on low-carb diets came out last year. It compared a low-fat diet in which you got 1,200 to 1,800 calories per day with a low-carbohydrate diet where you could eat as much as you wanted. The researchers kind of buried this part of it, by the way. They barely touched on the fact that this is a severely calorie-restricted diet compared with an all-you-can-eat diet. But what they found was that the low-carb diet did just as well. To me, this has been the most important observation in the field of obesity research: that you can have an effective diet that doesn't restrict calories. But the establishment has ignored that aspect of it. And in most of the studies that have been done, a low-carb diet actually does better than a low-fat, low-calorie diet."
HIGH FAT IS BETTER FOR YOUR HEART
"The idea that dietary fat causes heart disease is deeply, deeply ingrained. We all know the Atkins diet kills people--that's what we've been told, anyway. When I started eating this way, my wife made me get a life insurance policy. But over the past decade, dozens of studies have finally looked at the Atkins diet, and they show that heart disease risk factors improve more on this kind of low-carb diet than on the low-fat, low-calorie diet that doctors and the American Heart Association want you to eat. Your HDL goes up, which is the most meaningful number in terms of heart health. Small, dense LDL--which is particularly dangerous--becomes large, fluffy LDL. And not only does your cholesterol profile get better, your insulin goes down, and your insulin resistance goes away, and your blood pressure goes down."
"The low-fat diet that people have been eating in hopes of protecting their heart is actually bad for their heart, because it's high in carbohydrates. the public health effort to get everyone to eat that way is one of the fundamental reasons that we now have obesity and diabetes epidemics."
IF YOU HAVE A WEIGHT PROBLEM, IT'S NOT YOUR FAULT
"The past 40 or 50 years, obesity research has basically been an attempt to explain why obese people just don't have the moral rectitude of lean people, without actually saying that. It's terribly damaging. It's inexcusable, but it's still the conventional wisdom. Most doctors don't want to deal with obese patients because they think they're dealing with someone who simply doesn't care enough to do what they do: Eat in moderation, and exercise."
"I'll walk down the street and see somebody who's obese, and I can't see it as anything but a hormonal disorder. Not everyone gets fat from eating carbohydrates--it has to do with how sensitive your cells are to insulin and specifically how sensitive your fat cells are versus your muscle cells. But some huge percentage of the people who do get fat got that way because of the carbs in their diet. If you've been fat for a long time, getting rid of carbohydrates might not make you lean But the leanest you can be is on the diet with the fewest carbohydrates."
"Are there some cautions: Yes--some people feel low energy while their bodies adjust to this way of eating, though adding a little salt or bouillon to your diet can take care of that. A low-carb diet can reduce your blood pressure, too, so you might have to adjust your medication--if you have a medical condition, you should talk to your doctor first. But basically, I'm just saying, Eat what humans evolved to eat. Highly refined grains and sugars were not part of our diet for 99.999 percent of human history. Back when we were hunter-gatherers, we ate meat as often as we could get it, and when we ate plants, they were much tougher and higher in fiber than they are today--much lower in digestible carbs, in other words. This isn't a diet. The fundamental idea is, Don't eat the foods that make you fat. Beyond that, you can eat as much as you want."
Tomorrow - 5 ways to get started.