Who doesn't love a big bowl of pasta and a hunk of garlic bread for mopping up the sauce?
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Award-winning science writer Gary Taubes, that's who. In his latest book (read an excerpt from Why We Get Fat), Taubes has bad news for us wheat-o-philes: Carbohydrates, not fatty stuff like bacon, cream and butter, are what make us fat. So do even seemingly innocent foods like toast with jelly on top and a side of rice — anything that goes into the body as sugar or turns into sugar soon after. Sadly, that means many of our favorite nibbles and comfort foods are foes to our health. Soda and muffins are on the list, not surprisingly, but so are whole-grain bread, orange juice and that apple a day.
Q. But then why did this school of thought survive?
A. In part, because the research cost so much! If Congress tells NIH to spend X billion testing whether a fatty diet causes heart disease, you better find out that it does. Positive results are good for funding. Negative results are important in science, but in politics it's a different story. It's a fundamental problem in how we do public health science.
Q. So this unproven concept became "fact."
A. Once all the work was done, the money spent, the scientists needed to convince us they were right. Soon, the idea took on a life of its own. One report after another came out about how dietary fat is killing people. Big front-page headlines in all the big papers. After a while we believed it because it seemed crazy not to.
Q. If their theory was wrong, why do we get fat?
A. We get fat because we disregulate our fat tissue. Particular nutrients in our diet do this.
A. Yes, carbs are key. Once people believed fat causes heart disease, the thought was that instead of eating fat we should go high carb. So the base of the famous food pyramid is all carbs — pasta, bread, potatoes. Interestingly, until the 1960s, the conventional wisdom was that these foods make you fat. My mother believed that. A quote I love from a 1960s medical journal is "Every woman knows carbohydrates are fattening." The joke is they were right. Carbs are fattening.
And in the 1960s, just as we were learning why carbs were unhealthy, we threw out the paradigm and replaced it with the idea they are lean heart-healthy diet foods. No surprise that this corresponds with the beginning of an obesity epidemic.
Q. How do carbs work in the body?
A. It has to do with the hormone insulin. Insulin works to make you store calories as fat in fat tissue. Insulin, in concert with higher blood sugar, is what makes a fat cell fat. And the more refined, easier to digest, sweeter the food you take in, the higher the insulin goes.
Q. Why do we crave carbs?
A. This is partly speculative. When you eat carbs, your blood sugar goes up. Insulin gets secreted, and your body tells your cells to burn that blood sugar first, storing the fat for later. Now, as insulin comes down, you should release the fat you stored and burn it next. But if insulin stays elevated, which is what happens from eating a lot of these high-carb foods — maybe, sweet foods and drinks, in particular — your body continues to tell lean tissue to burn carbs even if you don't have them to burn. So you crave them. It's as though there's only one nutrient your body can use, or wants, to burn for fuel — carbohydrates.
Q. Why do I crave Coke and cookies more than potatoes?
A. Sugar is special. Sugar triggers the same circuits in the brain that addictive drugs trigger.
Q. Kids love carbs. Are we setting them up for obesity by letting them feed their cravings?
A. It scares me to see how carb-obsessed children are. In the book I talk about a vicious cycle: As women get heavier during pregnancy, if they're obese or diabetic to begin with, or develop what's called gestational diabetes, they give birth to children who are more likely to become obese or diabetic when they become adults. Generation after generation. Fatter and more diabetic means higher insulin levels. So bodies learn to perceive carbs instead of fat as the best nutrients to burn much of the day. Are we giving birth to children who, each generation, are more carb-needy, dooming them to problems down the line? It's possible.
Q. Do you restrict your own kids' intake?
A. I try to keep them off sugar without being a zealot and keep refined sugars and carbs and starches to minimum. But given a choice, that's what they want. I hate seeing overweight kids whose parents are forcing them to run or reduce the size of their meals. They can't run because they're storing energy as fat. They're hungry because they're eating the wrong foods. The effort to slim them down by starving them or making them exercise is misguided. The problem isn't that they are sedentary. That's a side effect of the disregulation of their fat.
Q. Should we all be avoiding carbohydrates?
A. Not everyone should be on the Atkins diet, that's not my argument. I want to get across the simple fact that certain foods are fattening and other aren't. Quantity and quality of carbs is what determines how fattening your meal is. Foods without carbs are not fattening, so you can eat as much as you want. You don't have to be a glutton, but you don't have to worry about it. They simply aren't fattening.
Q. Like what?
A. Well, foods with very few carbohydrates or in which the carbs are bound up with fiber and so relatively slow to digest. The first group is where it gets politically incorrect, because this group includes virtually all animal products — meat, fish, fowl, eggs, cheese, butter, etc. The second group is green leafy vegetables like broccoli, spinach and kale.
Q. How can anyone immediately improve his or her diet?
A. Stop eating easily digestible carbs and sugars. Again these foods are fattening, and if you don't eat them you'll be healthier. And they are almost assuredly the same foods that cause heart disease, diabetes, and I'd argue even cancer and Alzheimer's. My fantasy is that five years from now someone overweight goes to his doctor, and instead of the doc saying "eat less and exercise more," he says "these foods are fattening — the carbohydrate-rich foods and sweets. Don't eat them."
Q. I'd hate to think I can never have another cupcake.
A. I'm writing both to people concerned about weight and also doctors who are treating obese people. If you want to lose 10 pounds, maybe you just give up refined sugar, or have pasta less often. For someone 100 pounds overweight who wants to be lean as possible, they have to do more. It's about dose. What you can handle depends on your body and the extent of the problem. For someone who weighs 300 pounds, moderation probably won't make a bit of difference. For someone who put on 20 pounds since college, maybe moderation is the answer and the occasional cupcake is not a problem.
Q. Why are runners so skinny, if exercise doesn't make you thin?
A. We think running makes them that way, but it isn't correct reasoning. Leaner people make better runners, and are more likely to run. The reason lean people are good runners is because their bodies want to burn their energy rather than store the calories. The energy drives them to become runners.
Q. Running isn't for everyone?
A. No, contrary to expectations, you can't take a sedentary person and force him or her to exercise and expect the fat will melt away to make a thin person. You can't starve a fat person into a lean person any more than you can turn a basset hound into a greyhound by forcing it to run. You end up with an exhausted, starved basset hound. And given time, and access to food, that basset hound will plump up again because that's its nature. The same is true for those of us who are fat, but that nature depends on the eating environment — one that's carbohydrate-rich.
Q. What do we do?
A. We don't have to eat the foods that promote fatness. Low-fat foods replace fat with carbs. So if you are eating bagels with low-fat cream cheese and drinking skim lattes, you are eating in a way that promotes fatness. If you remove the carbs, you can be significantly leaner.
Q. I assume you've cut carbs. What do you miss?
A. I miss pasta. And orange juice in the morning. Fortunately, I'm a carnivore, so I'm happy to eat meat all the time. Not that you have to eat only meat to avoid carbs. I eat green vegetables because my mother taught me to eat them, and I like them. I probably eat more veggies than I used to because I'm replacing the starch with the vegetables. I eat a lot of eggs and bacon, a lot of beef and chicken.
Q. Do you lose your taste for sweets if you give them up?
A. That sweet tooth does vanish. For me, now I can't even imagine a big glass of OJ — it would be too sweet. It's like any addiction. When I was younger I smoked cigarettes — and I couldn't imagine life without cigarettes. But when I gave it up, the intense cravings lasted about three weeks. That was followed by a couple of years of simply missing the cigarettes, when I always had to be on my guard that I might slip and go back to smoking. But after a while, I couldn't imagine going back, and I found it hard to imagine why I ever smoked. It's true of nicotine, bad relationships and carbs.
Q. What have been the results for you?
A. Personal stories like my own are anecdotal, which means they don't say much scientifically. But I first tried eating like this as an experiment 10 years ago — an economist at MIT suggested I try it — and I've stuck with it. I weigh 10 pounds less than I did when I started, but I was gaining two pounds a year at the time, so I might be 30 pounds less than I would have been otherwise. I do have more energy. I need less sleep. My skin is clearer. I could go on, but I start sounding like an infomercial, which is precisely what I'm trying to avoid.
Q. What is your main point?
A. The point I'm making in this book is that this is about science, and when the evidence is studied without preconceptions, what it tells us is pretty clear.
Jennifer S. Holland lives in Maryland.