Americans are overweight because we eat too much and don’t exercise. Right? A new book says: Guess again.
In Why We Get Fat, award-winning science writer Gary Taubes challenges the conventional wisdom about what makes us fat. He looks back at decades of weight-loss studies and concludes that the real culprit is not lack of exercise, too much fast food or too little willpower. Rather, it’s the quantity and quality of the carbohydrates in our diets–as well as how our bodies respond to them.
His argument is fascinating, and compelling enough to land his work on the cover of The New York Times magazine this year. It’s especially relevant if you’ve struggled–and failed–to keep weight off.
Here, he discusses Why We Get Fat, and what it means to FOFs.
- What’s the top-line philosophy of your book?
- The idea that we get heart disease from the fat in our diet is misconceived and based on bad science. The idea that we get fat because we eat too much and are too sedentary is misconceived and based on bad science. And the culprit in both of those cases is most likely the quantity and the quality of the carbohydrates in our diet.
- You talk a lot about the science behind this concept in your book. Can you explain in layman’s terms how carbohydrates make us fat?
- When you eat carbs, it raises your body’s insulin levels. Insulin is the primary regulator of fat accumulation. If you raise insulin levels, you store fat. If you want to get rid of the fat in your tissues, you lower insulin levels. That’s not controversial–it’s endocrinology 101.
- So what happens when you eat a high-carb diet?
- The more carbs you eat–especially refined carbs such as sugar and high-fructose corn syrup–the more insulin your body produces. That insulin makes you store calories as fat instead of allowing you to burn them as fuel. So not only do you gain weight–i.e. get fatter–but you’re hungrier because of it. People who eat a low-fat, high-carb diet tend to get hungry every two hours. Over time, you can develop insulin resistance. That means your body has to secrete even more insulin in order to regulate your blood sugar. You have more insulin in your blood, so you body craves carbs even more.
- Why are people getting fatter now? Are we eating more carbs than we used to?
In the 1970s and 1980s, a low-fat, high-carb trend took hold. Federal dietary guidelines began touting carbohydrates as heart-healthy diet foods. The American Heart Association told Americans to cut their fat intake. At the same time, the market was flooded with low-fat, high-carb “diet” foods–low fat yogurt, health food bars, and sugary drinks filled with healthy sounding ingredients like ginko biloba and ginseng.
- This sounds like Atkins–cut out everything but meat and cheese? Don’t we know that diet isn’t healthy either?
- It is a lot like what Atkins said. He read a lot of the same scientific literature I did, only 40 years earlier. But that misses the point. My book is about what makes us fat. The point is, carbohydrates are literally fattening. What you do with that information is a different issue.
- In the book, you talk about certain cultures that eat a high fat, high protein diet.
- The Masai people of Africa eat the highest fat diet in the world–mostly animal fat and protein. But they’re incredibly lean, fit and healthy. The Inuit people–in the Arctic–ate a 100-percent animal protein diet–mostly fish, caribou and walrus. No fruits and vegetables. And they were incredibly healthy, with low heart disease, virtually no cancer or diabetes, and incredible physical stamina. Explorers who lived with Inuit a century ago described them running beside their dog sleds for 20 miles–effortlessly.
- Are some people more prone to have problems with carbs than others?
- Yes. There are a million nutrition and health experts out there who think, ‘if everyone just did what I did, they’d be thin, too.’ The truth is, our bodies are different in the way they metabolize carbs. For some people, it puts them in a mode to store fat–these are the people who are predisposed to obesity. We all know who we are. Growing up, my brother was three inches taller than me and 30 pounds lighter. He’s naturally lean. My body wants to store fat and his doesn’t. The point I’m making is that if thin women and overweight women all grew up in a world without carbs, they’d all be relatively lean.
- So what would happen if your brother ate a high-carb diet?
- He wouldn’t get fat, but he might get heart disease or a fatty liver or insulin resistance. Even if you’re not someone who stores fat, carbs effect your body.
- Many women over fifty find that after menopause, they suddenly begin to put on weight. Do you attribute this to carbs as well?
- Actually, loss of estrogen–which happens during menopause–has the same biological effect as increasing carbohydrates. In the 1970s, there was study where they removed the ovaries from rats–the same thing as removing estrogen. The rats ate voraciously and got fat. But they got fat even if they weren’t allowed to eat any more than they did when they still had their ovaries.
- So what’s the solution? How should we eat?
- We’re all different. But the basic message of my book is that not all carbs are bad, but that the refined ones, the easily digestible ones like potatoes and sugars are the problem, and any diet without those things will be healthier. Sugar and high-fructose corn syrup are almost assuredly the worst. White flour would be next. Any refined grains aren’t good–potatoes, pasta, bagels. You can still eat green leafy vegetables and other low-glycemic index carbs such as minimally processed grains and legumes, because those aren’t fattening. They don’t have the bad effects on insulin and blood sugar.
- What if you’re already obese or insulin resistant. Should you take more extreme measures?
- If you cut out carbs, your body will start burning fat. And if you’re obese, you have a lot of fat to burn, so the less carbs you eat, the better. The logic of cutting out all carbs–like the Atkins diet–is that this is like an addiction. If you don’t want to get lung cancer, you don’t cut down to 10 cigarettes a day–you quit. Cut them all out, get rid of the cravings. Once you get to the weight you feel good at, you can test out some of the carb-rich foods you still miss. If you miss apples, for instance, have an apple every day. See if you gain some weight.
Science WriterGary Taubes is an American science writer. He is the author of four books including Good Calories, Bad Calories (2007), and Why We Get Fat (2010). He has won the Science in Society Award of the National Association of Science Writers three times. He is currently at work on a book about sugar and high-fructose corn syrup with help from a grant from The Robert Wood Johnson Foundation.