A typical dialogue on diet goes something like this:
Expert: We don't have any known way to make obese people thin except gastric bypass surgery, which has a 2% mortality rate by itself.
Thin person: But I am very thin!
That's about 50% of the conversation in the comments to the Paul Campos interview. It's about as useful as the following exchange:
Expert: We don't have any known way to make short people tall, except for extreme surgeries and hormone injections.
Megan: But I am 6'2"
Let's explore the possible rejoinders to this:
1. Obesity is increasing in the population, so it can't be genetic.
Well, average height is also increasing in the population. Does that mean that you could be as tall as me, if you weren't too lazy to grow?
Twin studies and adoptive studies show that the overwhelming determinant of your weight is not your willpower; it's your genes. The heritability of weight is between .75 and .85. The heritability of height is between .9 and .95. And the older you are, the more heritable weight is.
2. Height doesn't have anything to do with health.
Actually, it may. Being taller puts a greater strain on your circulatory, cardiovascular, and musculoskeletal systems. Tall people are prone to all sorts of problems at higher rates, especially in their back. That doesn't make it any more sensible to suggest that we need a public health campaign to help tall people shrink.
3. We don't have any good way to make people shorter, but we do know how to make them lose weight.
Actually, this is rubbish: we don't know how to lose weight. Some of the things Paul Campos is saying about obesity are controversial, but this isn't. Every single study which has attempted to make overweight people get thin without very risky surgery has failed completely and utterly. Fewer than 1% of patients ever keep the weight off.
Highly educated people who have managed to get their body weight down 5-10% from where their body naturally wants to be confuse what they are doing with what someone obese enough to cause significant medical problems would need to do, which is get their weight down 50% or more from where their body apparently wants it. They are not the same thing. The amount of weight loss that these sanctimonious slenderizers have achieved has no statistically significant health benefits. Let me repeat: losing twenty pounds will not make you healthier. If you have diabetes and high blood pressure, there is an extremely modest improvement in test results. Unfortunately, it's even harder for diabetics to lose weight than the rest of us.
Fat tissue makes people want to eat--it sends out for takeout. And hunger is a signal on par with thirst or pain. You can ignore it, if you have sufficient willpower. But just as most people can't withstand torture (a minority can), most people can't ignore the constant demand from their body for food. Gina Kolata's Rethinking Thin describes it thus:
Every time the result was the same. The weight, so painstakingly lost, came right back. But since this was a research study, the scientists looked at more than just weight loss . . . they measured metabolic changes and psychiatric conditions and body temperature and pulse. And that led them to a surprising conclusion: fat people who lose large amounts of weight may look like someone who was never fat, but they are very different. In fact, by every measurement they seemed like people who were starving.
On every count, the weird, bizarre, almost depraved behavior that Ancel Keys reported when he studied young men who were deliberately starved in his experiment during World War II was just like what Hirsch observed among the formerly obese subjects at Rockefeller University Hospital. Something ws driving these people to regain their weight, and it was not a deep-seated desire to be fat.
Their metabolisms, for example, had changed so that they hung onto, clung to, every calorie that was consumed, making it harder for them to stay thin. Before the study began, the fat people had a normal metabolism--the number of calories burned per square inch of body surface was the same as for people who had never been fat. That changed substantially after they lost weight, with fat people burning 24% fewer calories per square meter of surace area than were used by people who were naturally thin.
The Rockefeller subjects also had a psychiatric condition that had been termed "semi-starvation neurosis". Hirsch's patients dreamed about food; they fantasized about food, or breaking their diets. They secreted food in their rooms. They daydreamed about food. And they binged . . . eventually more than fifty people went through the months-long process of living in the hospital and losing weight, and every one of them had the physical and psychiatric symptoms of starvation.
If when eating a normal 2,000-2,500 calorie diet, you do not spend significant amounts of your day fixating on food--fantasizing about it, binging, hiding it, strategizing how to procure it--you do not have anything interesting to say to someone who is struggling with obesity. You do not have better willpower than they do. You do not "care about myself" more. You are not more "serious about a healthy lifestyle" because you took off the eight pounds you gained at Christmas. You are no more qualified to lecture the obese on how to lose weight than I am qualified to lecture my short friends on how to become tall. You just have a different environmental and genetic legacy than they do. You're not superior. You're just somewhat thinner.
To put it another way: I have NEVER had a BMI above the normal range. How much more awesome am I than you? 30%? After all, you have to work at it. My willpower is apparently 100% natural.
I fearlessly predict that more than one person will respond with some variation on "there were no fat people in concentration camps/but I told you, I totally lost 20 pounds last year by taking up marathon running!" Yes, we could solve America's obesity problem by putting everyone in the country on sawdust bread and cabbage soup. We could also just shoot anyone whose BMI is over 28. Are these good solutions? Because short of that, we don't have much.
4. Then we need to intervene with the kids, so they don't get fat in the first place
Schools have tried this; so far, it's no more successful than adult interventions. You can get a very small effect over the short term, but eventually, the kids start eating again. Yes, school meals are crap. I assure you, they were also crap thirty years ago, and sixty years ago. Yes, P/E has been cut in some schools, but there's little evidence that exercising makes you lose weight by itself. Unless you control their access to food completely--and you can't--those kinds of environmental interventions don't work.
5. So why is America getting fatter, Miss Smartypants?
Some combination of the following:
1. Hyperpalatability of food: the Seth Roberts/chain restaurant haters hypthesis. The processors have perfected combinations of fat, salt and sugar that addict us, causing us to eventually swell up like a balloon.
But French restaurants have been doing this for over a century, and for most of that century, thinness has been inversely correlated with poverty. Your body doesn't care whether it gets its fat and sugar from a Ho-Ho or a Chocolate Eclair.
2. Increasing prevalance of corn in the supply chain: the Michael Pollan/Cato hypothesis. Maybe: corn doesn't seem to be very good for you. But I'm skeptical of monocausal hypotheses.
3. Calories are getting cheaper. Self explanatory. In my view, the dominant reason. People eat more calories because they like it, and can afford to.
4. Animal fat. Eh, maybe. We sure eat a lot more of it than we used to. But we eat a lot more of everything. And without controlling for socioeconomic status, it's hard to tell whether vegetarians are thinner.
5. Larger portions. Special case of "calories are getting cheaper". I think it's less persuasive than many people think. It's true people will eat a great deal at a sitting if you give them a great deal. But if people were so easy to fool, long term, about their caloric intake, we'd all weigh eight zillion pounds.
As I pointed out elsewhere, a simple error of 50 calories a day--half a slice of Pepperidge Farm All-Natural Whole Wheat Bread--would make us gain five pounds a year apiece. Given inherent calculation error, no one is watching their calories this carefully. Our appetites are doing the work for us. Maybe you eat an extra 2,000 stealth calories at dinner, but you're not so hungry the next day. Conversely, try dining on Macaroni Grill's new 390 calorie scallop salad. Unless you're on a permanent diet, I bet you feel peckish before bed.
6. We're getting older. It is normal to gain weight as you age, unless you are in a fairly calorie-deprived environment. An aging demographic will naturally produce a fatter population. This does not account for the growing number of super-obese people with BMIs over 40, even over 50. But it accounts for at least some of the central shift.
7. We quit smoking. Smoking makes you quite a lot thinner, particularly after 25. Now that fewer adults smoke, more adults are gaining weight.
Reasons we aren't getting fat:
1. We don't know how many calories are in the food we're eating. I'm pretty sure my great-grandmother didn't either. She still knew that pound cake made you fat, and lettuce didn't.
2. We exercise less. We haven't gotten noticeably more sedentary in the past decade or so, but the weights keep shooting up. Also, there's no evidence that exercise makes you lose weight--ever discussed dieting with a long distance runner or ballerina?
3. Poor people don't have access to good groceries. They had even worse access ten, thirty, fifty years ago. Using starch and cheap sugar as substitutes for vegetables and lean meat is not a recent invention--George Orwell discussed it in the Road to Wigan Pier. Frozen vegetables are very good for you, and within the budget of everyone.
4. We're eating too many empty carbs. Processed carbs entered--and dominated--the American diet in the second half of the nineteenth century. Working people at the turn of the century ate virtually no meat, little fat, and few vegetables; their diets were mostly beans, white flour, polished rice, pasta, and potatoes, washed down by sugared coffee or tea. Folks who want to blame the "food pyramid" should read a cookbook from 1950. Grandma didn't need a food pyramid to rely mostly on carbs; carbohydrates were what she could afford.
There is a really, really deep resistance to the idea that appetite is as powerful a modulator as it appears to be. I can't help but believe that at least part of this is simply that thinness, especially for women, is tightly correlated with socioeconomic status and urban living, and nice upper middle class people who have been on a slight diet for most of their adult lives just cannot believe that a) this isn't making them healthier and b) it isn't making them better people.
But while a lot of what Paul Campos says is controversial, this isn't. You can find the same results yourself by reading any study of weight loss: outside of gastric bypass surgery, no system has ever produced any significant long-term weight loss. None. As Paul remarked to me once, "We've run this experiment approximately 220 million times and the result is always the same. Why can't anyone believe it?"
His controversial assertions are about the correlation between weight and health, and the benefits of gastric bypass surgery. I'll leave those for another day. But even if he's entirely wrong about those things, we're still left with the core fact: we have tried, and failed, for more than fifty years, to find a way to make people thinner. Arguably, we should stop. Certainly, we shouldn't count on any cost savings from controlling obesity to fund our future health efforts. It is much more likely than not that obesity will stay the same, or get worse.
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