Fat Head Why We Get Fat: Interview With Gary Taubes
Fat Head: Dr. Robert Lustig insists it’s fructose that makes us insulin resistant, not starchy foods. If he’s right, then it was the Coca-Cola and Captain Crunch that turned me into a fat kid, not the mashed potatoes. But as an adult, I’ve avoided sugar yet found that starches most definitely make me gain weight. So assuming for the sake of argument that Lustig is correct, would you say that once fructose has done the damage, we lose our tolerance for carbohydrates in general? If so, why?
Gary Taubes: That’s exactly the possibility I’m discussing. Once you become insulin resistant, your body responds to carbs by secreting more insulin. So it is quite possible — and laboratory work backs this up — that sugar causes the initial insulin resistance because of the effect of the fructose on the liver. So if we never had sugar, we’d be able to eat the other carbs with relative impunity. But being possible doesn’t mean it’s true. I suspect it is, but I’m not sure exactly how this can be tested.
And I agree with you: the world is full of obese and diabetic people who know enough not to eat sugar, but remain obese and diabetic. I could avoid sugar and go back to eating starches and put on 20 pounds of fat effortlessly. I’ve done it in the past — distant past. So I don’t buy the idea that avoiding sugar is enough to make an obese person lean again. And the people I know who believe that all tend to be somewhat plump despite their beliefs. In fact, I recently heard Dr. Lustig give a talk in San Francisco, and he acknowledged that he still has a weight problem, but doesn’t know what to do about it. Hmmm….
Fat Head: Have you come across any evidence that starches can turn people into fat diabetics without fructose being part of the diet?
Gary Taubes: It’s tricky. Typically consumption of sugar, white flour and starchy vegetables all tend to go hand-in-hand. So it’s hard to tease out this one. I suspect beer could, but I don’t know if even beer drinkers who don’t eat sugar tend to become diabetic or not. What we’d need is a population of white-flour eaters who didn’t eat any sugar at all. If we could find such a thing, naturally, then we’d have some idea.
Fat Head: In Why We Get Fat, you wrote that some people might have to give up dairy products and nuts to lose weight. Dr. Mike Eades has also mentioned that nuts and cheese seem to inhibit weight loss in some low-carb dieters. What is it about those foods that can stall weight loss? Is it just that they’re so calorically dense, or do they produce a higher insulin response than their low carbohydrate content would suggest?
Gary Taubes: I think the caloric density thing is nonsense. Remember, I’m trying to get every last one of us away from thinking in terms of calories as the variable of interest. What we want to know is whether these foods stimulate insulin secretion, or cause insulin resistance, or have some other effect on the storage of fat in the fat tissue or the oxidation of fatty acids by other tissues in the body. So nuts still have carbs in them, and for some people they might contain too many carbs. Same is true for nut butters.
Dairy products can stimulate insulin secretion beyond what you would expect from the carbohydrate content. I don’t know if this is true of cheese because I’ve never seen data on this, but it is possible. And some cheeses could be better than others — hard cheeses, for instance, may be better than soft cheeses.
Fat Head: You wrote something in Why We Get Fat that I think every frustrated dieter needs to hear: the proper diet will help us become as lean as we can be, but not necessarily as lean as we’d like to be. Once we become fat, is there a limit to how much fat we can lose without starving away our lean tissue? If so, what’s the barrier to mobilizing and burning those last 10 or 20 pounds of excess fat?
Gary Taubes: Simple answer, I don’t know. But it’s obvious that not every woman can have the body of an Angelina Jolie, regardless of how few carbs they eat. And not every man can have the body or the body-fat percentage of, I don’t know, a Matthew McConaughey, one of these actors who’s always taking his shirt off in movies.
That’s for starters. Some of us are wired to have more body fat than others from the get-go. Then I think when we grow up in a carb-rich environment, some degree of chronic damage is done to the way we partition fuel. Maybe our muscle tissue never quite loses its insulin resistance, or our fat tissue remains more insulin sensitive than it would be had we never seen carbs. Maybe our pancreas secretes a little too much insulin.
It’s hard to tell, but the way I describe it is this: if I grew up in a hunter-gatherer environment — and my mother did as well, because there are effects that are passed from mother to child through the uterus — I’d probably weigh around 175 pounds, even as an adult. Had I stopped eating carbs in my late teens, I might naturally weigh about 190 or 200, which was my football weight in high school. The fact that I not only kept eating carbohydrates into my forties but gorged on them during the low-fat, you-can’t-get-fat-if-a-food-doesn’t-have-fat-in-it years of the late 1980s and early 1990s means the best I can do now, even eating virtually no carbs at all, is about 220. And there’s nothing I can do to go lower, short of starving myself. Semi-starving myself doesn’t work. I tried that long ago.
Fat Head: So what’s the message for those people? Lose what you can and focus on being healthy, as opposed to obsessing with squeezing into a size-8 dress?
Gary Taubes: Precisely.
Fat Head: One of the anti-Taubes articles going around the internet claims that we don’t need insulin to store fat, and that insulin is an appetite suppressant. Can we store any significant amount of fat without insulin? If so, why do untreated type 1 diabetics waste away?
Gary Taubes: Short answer, probably not. We don’t need insulin to burn glucose for fuel, but if we don’t have insulin, we don’t store fat.
Fat Head: In Why We Get Fat, you also stated that elevated insulin in the brain suppresses appetite. Since so many obese people have high levels of circulating insulin, why aren’t their appetites suppressed? Is there a difference between the effects of insulin in the brain and insulin in the bloodstream?
Gary Taubes: That’s the key point. A few years ago I was interviewing the director of the Joslin Diabetes Center, and I asked him what the role of insulin was in obesity, and he said its role was to suppress appetite in the brain. And it does. Three researchers at the University of Washington spent 10 to 15 years trying to convince people that insulin had this role. They had injected insulin into the cerebral spinal fluid of primates and it did indeed suppress appetite.
The problem is these people succeeded so well in their crusade that the rest of the community — this guy at the Joslin among them — simply forgot about what insulin does in the body, which is to promote fat accumulation and energy storage. And it makes perfect sense that a hormone that responds to eating will work to store fuel in the body while it also works, secondarily, to tell the brain that fuel is coming in and eating can cease in a bit. That’s the kind of feedback loop you find all over homeostatic systems. But the fundamental issue is that in the body, insulin promotes fat accumulation and that’s where the problem is.