A while ago, I promised to share my impressions of Gina Kolata’s Rethinking Thin. I finished the book last month, but I wanted to let my response percolate before posting. The biology of metabolism is one of my hot-button issues, and I had high hopes for this book. With a hefty subtitle like “The New Science of Weight Loss – and the Myths and Realities of Dieting,” I expected a forceful argument, perhaps even a jeremiad, against those dietary myths. The book is, somewhat disappointingly, not a jeremiad. But it is interesting, and, I hope, part of a gradual shift in attitudes toward metabolism.
The fruit of Kolata’s research is partly a history book, recapping America’s obsession with weight loss from the 1800s on. As a history of dieting, it’s eye-opening: the same kinds of diets have been recycled for over a hundred years. You thought Atkins was new? Not so much! It’s also partly a review of the latest obesity research – but that research points too many directions, and is far too complex, for a review of such brevity to satiate scientifically informed readers. Thirdly, it’s a sensitive portrait, though a somewhat superficial one, of dieters who embody a statistical inevitability: failure to keep lost weight off. Their initial euphoric success and subsequent depression are what tables and figures in scientific papers never capture.
In introductory classes, I often assign non-fiction books that model how science should be practiced, while also demonstrating how real-world preconceptions, politics, and personalities inevitably derail perfect objectivity. Rethinking Thin is a book in that vein: Kolata takes on preconceptions about fatness, some deeply ingrained in our culture, and discusses how research has been directed and constrained by those preconceptions. Occasionally, the prose goes off the deep end:
Without phen-fen, Carmen was at a loss to control his weight. “I stopped, and the weight came back,” he recalls. What to do? He had no interest in trying another water-cooler diet, so, like the swallows of Capistrano who, legend has it, return each year to an old ruined church where they had been saved in the past from an innkeeper who destroyed their nest, Carmen returned to Jenny Craig.
But aside from a few inexplicable clunkers like that one, the book is pleasantly readable. It’s full of engaging details, like Chicago teen Yvonne Blue’s 1926 diary (“Three months in which to lose thirty pounds – but I’ll do it – or die in the attempt”), or the “Dr. Atkins of his day,” Horace Fletcher, who advocated weight loss through “divine mastication” (chewing), which was popularly called Fletcherizing.
What Rethinking Thin is not: a diet book. It is not a how-to book, nor a consumer report recommending one diet over another. And it is not – as some reviewers have suggested – a license to give up and be fat. There’s an important distinction between acknowledging the substantial genetic influence on obesity, and abdicating personal responsibility because of it.
For readers who have struggled with weight issues, much of this book will seem disturbingly familiar. Several individuals in the book confide their intense feelings of relief when they realize that other people have the same difficulties with food that they do. (My response to the book was also very personal, as will become obvious from this review). But though catharsis is pleasant, the people who should read this book are the people who don’t struggle with weight loss – especially health professionals who advise patients on dieting. I doubt many will read it, since a problem that one does not share (and an entire nonfiction book about that problem) is generally much less interesting than one’s own problems. I understand that if you’re naturally thin, it can be hard to relate to someone who is fat – you wonder why they don’t simply eat less. You may even have contempt for their lack of self-control. But the fact is, losing weight is not the same challenge for everyone, and the biology backs that up.
If you don’t struggle with your weight, consider this: do you congratulate yourself on avoiding unhealthy foods that you don’t like? Probably not, because you don’t have to resist cravings or desires to do so. It’s much harder to avoid your favorite foods – the ones that make your stomach growl and mouth water! So wouldn’t it be harder to resist food in general, if you experienced a constant, 24/7 struggle against gnawing hunger – the same sensation you’d have if your favorite food was sitting temptingly in front of you?
The truth is, some people really are hungry ALL the time. I know this because I’m one of them. I don’t know what “eating until you’re full” feels like. When I say “I’m full,” it means “I’m not going to continue eating now, because it would be imprudent/indelicate/unnecessary.” But am I still hungry? Heck yes! My stomach growls pretty much all day, at night while I’m trying to sleep (fun), while I’m jogging. . . talk about embarassing.
Why does this happen? I have no idea, but I think it’s genetic. Kolata’s book presents consistent evidence that “the children who are going to get fat are those whose biological parents are fat”; 80% of adopted children with two obese birth parents became obese; only 14% of the children with nonobese parents did. Metabolism is genetic. Body shape is genetic. But does a genetic “hunger overdrive” give me license to eat food nonstop and gain ridiculous amounts of weight? Absolutely not! I may be at a disadvantage, but I’m still responsible for what I eat. I get the distinct impression that people who decry or deny the “genetics of weight” (and blame Rethinking Thin for promoting it as a cause of obesity) fear that genetics will mean a complete abdication of personal responsibility. I don’t agree at all: clarifying the role of genetics helps to give an individual control, by defining the parameters of their problem. However unreasonable or destructive, constant hunger is a real, physiological impulse that some people have to resist. Telling these people “it’s all in your head” isn’t helpful. What’s wrong with “I realize you feel this way, and it’s not your fault, but if your goal is to be thinner, you need to develop strategies to control this hunger” ? Wouldn’t the latter advice be more constructive than denying the problem exists?
You can probably sense that I’ve had a few unpleasant run-ins with nutritionists myself. In fact, I’ve been reprimanded for “lying” about my food intake, because according to those one-size-fits-all medical charts, it’s simply impossible that I weigh what I do, exercise as much as I do, and eat as little as I do. If I estimate my basal metabolic rate (BMR), I should be eating almost a thousand more calories each day than I do! I’ve kept meticulous food/exercise diaries that would make a dietician’s head spin, because the numbers don’t add up.
How do I explain this? Simple. These BMR estimations don’t work for everyone, because not everyone’s metabolism runs at the same rate. (If I assessed my BMR directly by measuring oxygen consumption, it would be much more accurate, but I’ve never had the pleasure of an expensive VO2 test). Rethinking Thin recounts seminal studies that demonstrated this decades ago – subjects’ bodies readily buffered experimental changes in caloric intake, revving up or slowing down to maintain weight near their set point. Naturally thin subjects had to eat a truly shocking amount of food to put on weight; they couldn’t keep it on! Why, then, is it hard to accept that people’s metabolisms are heterogenous to start with? I’d have gotten my weight under control much faster if the nutritionist I saw ten years ago had said “huh. You must have a slow metabolism. It’s not fair, but you’ll have to eat less than the recommended amount. Let’s work on doing that, in a healthy way.” (I’m sure there are nutritionists somewhere who say things like that, but I’ve never had the pleasure to meet them).
So how much do I eat, when I’m trying to lose a few pounds? I never give a number anymore, because of the knee-jerk response I get. I’ve been called anorexic, despite being well on the chunky side of the bell curve. (“Do I look anorexic?” usually silences those critics). I’ve also been accused of crashing my own metabolism (and causing my weight problem) by eating so little my body goes into “starvation mode.” Aside from the unlikelihood of being in “starvation mode” while having plenty of energy, plenty of fat, and running several miles a day, I only started eating substantially less in my late twenties – after I got the confidence to define my own diet based on what felt right, not what I was told to do. Since then I’ve lost weight, not gained it.
The only proven way to lose weight is to 1) reduce calories and 2) increase expenditure through exercise. Yet society seems reluctant to endorse option 1, as if there is an unforgivably slippery slope between endorsing a low caloric intake, and promoting Nicole Ritchie-style emaciation. Why our society persists in defining beauty by supermodels who are extreme outliers on the curve of human morphology, and what that does to young girls’ self-esteem, is another post entirely. Kolata points out that despite the revisionist conception of Marilyn Monroe as a curvacious “size 12,” the sex goddess was really only 115 to 120 pounds – hardly today’s 12; but Rethinking Thin spends only one chapter on the changing history of body images. This is disappointing but understandable – it is a different issue, and an important one, that deserves its own conversation. Especially in a holier-than-thou age where talking heads on Fox News accuse 17-year-old Jordin Sparks, winner of American Idol, of setting a bad example simply by existing:
When I look at Jordin, what I see is diabetes, I see heart disease, I see cholesterol. . . .she’s a vision of unhealth. (Meme Roth)
Jordin is 5′ 10″ and according to People, a size 12.
Although I would never endorse eating disorders, or the bizarre delusions of people who think 17-year olds should be pilloried on national media outlets, I would argue that some of us can responsibly reduce food intake pretty far, and in fact need to do so, if we want to be a socially acceptable size or have an athletic build. By denying this, health professionals enforce all-or-nothing choices that are fodder for eating disorders. If you can’t get to a healthy weight by dieting in the “approved” way – and not all of us can – you might give up completely and be unhappily fat, or stop trusting medical advice at all, take extreme measures, and hurt yourself in the process. Your self-esteem shouldn’t be about numbers on a scale (bathroom scale OR food scale); it should be about cardiovascular, mental, and immune health!
This brings me to a group of people who get suprisingly scant coverage in Rethinking Thin: devotees of caloric restriction. Kolata touches on the origins of counting calories, first popularized by early twentieth-century diets books like How to Live by Fisher and Fisk, or Lulu Peters’ Diet and Health, with Key to the Calories (1918), which recommended a diet of 1200 calories per day:
You will be surprised how much 1200 calories will be if the food is judiciously selected. You may be hungry at first, but you will soon become accustomed to the change. I find that dry lemon or orange peel, or those little aromatic breath sweeteners, just a tiny bit, seem to stop the hunger pangs; or you may have a cup of fat-free bouillon or half an apple, or other low calorie food. (L.H. Peters)
According to Kolata, “Diets became stricter and stricter, with doctors, around 1928, recommending eating just 600 to 750 calories a day to cure severe obesity.” Who eats that much? Some practitioners of caloric restriction eat almost that little – and do very well.
Caloric restriction (CR) is a diet plan in which the caloric intake is reduced by at least 20% from the recommended amount. CR definitely works, and not only to lose weight. In lab animals, it also significantly extends lifespan – a benefit which may or may not apply to humans. (Health and longevity are the stated goals of CR – not weight loss per se).
But disappointingly, “caloric restriction” isn’t even in Kolata’s index. Her book is about popular diets and the science behind them; despite the efforts of CR proponent and diet guru Roy Walford, CR is hardly popular. It can be grueling, and Americans love their food – drugs like Alli, which have limited benefits but let you eat, will always be more attractive. CR is also controversial. The Mayo clinic is hesitant to recommend CR. And a Slate article last month compared CR to anorexia. (Of course, this is the same publication that ran this story in February, in which 1500 calories a day were termed “starvation.”)
So what do we do? For the genetically unlucky, is obesity inevitable – something we can only combat with starvation? Animal models haven’t answered that question. Carl Zimmer, writing about mouse genetics for Discover, describes Gary Churchill’s efforts to find the elusive fat gene:
Rather than focus on a single gene, Churchill and his colleagues decided to explore the entire weight-control network. They selected a big, lean strain of mice and mated them with small, fat ones. The offspring of this union grew to many different sizes and weights. Churchill and his team then measured how large the animals grew and how much of their body weight was fat versus muscle. They also measured how the fat was spread out on each mouse. Like us, mice tend to accumulate fat in certain places, like their haunches and their bellies. Finally, the scientists scanned the genome of each mouse for hundreds of markers to see which ones were linked tightly to each trait.
The map they came up with looks like a flowchart from hell. Churchill’s group identified a dozen sites in the mouse genome where genes are influencing the body weight of mice. But the genes have different effects. Some make mice large-bodied, and being big makes mice more likely to get fat. But they also found genes that had separate effects on both body size and fat levels. In some cases, the same gene could make a mouse both big and lean. Other genes influenced only how fat the mice were, with no effect on their body size. Still other genes determined the size of different fat pads. One region of mouse DNA appears to make mice fat overall while actually making the fat pads on their haunches smaller.
This sounds very much like human beings, doesn’t it? The genetic “flowchart from hell” could be why one diet doesn’t fit all; why the Atkins diet may work for your aunt but makes you get fatter; why your friend who never exercises is still thinner than you are. It’s why some people put fat on their thighs and some deposit it on their midriffs.
Can we fight the flowchart from hell? Kolata seems doubtful, and this is where I am most disappointed with her book. In the end, the dieters she’s tracked don’t keep their lost weight off, and the book concludes in a tone of sadness and powerlessness. Kolata even speculates that the obesity epidemic could be inevitable – some unforeseen consequence of a modern lifestyle which we can do little about. She never says we’re definitely doomed to be fat – just that, for many of us, we’ll have a constant struggle to avoid it, and almost all of us will fail (a grim reality borne out by statistics).
I agree that no diet will be a quick cure for the obesity epidemic. I hope Kolata’s book persuades a few more people of that, or at least conveys the hardships naturally heavy people face as they fight their own bodies. But I wish her book had reframed the obesity problem more optimistically, as an individual problem, with individual solutions. To paraphrase Tolstoy, every naturally thin person is alike, but every heavy person is heavy in their own unique way, for their own reasons – genetic and otherwise. If we accept that, we might see more creative ways to approach obesity.