Our experience is often true of obese people. They spend more energy on dieting, starving, working to control hunger, than anyone else. And most of them do lose thirty, forty, ?fty pounds -- many times over -- exhibiting a lot more willpower than most thin people have ever had to show.
So what do thin people have over those who are extremely overweight, if not self-control? Luck. Or, more speci?cally, genetic luck. The genes that put their ancestors at grave health risk thousands of years ago, by making it dif?cult to hold on to fat stores in times of food scarcity, are the very genes that are keeping them thin and largely free of health risks today in the face of food overabundance.
Thin and even mildly overweight people often scoff at that notion, as I know all too well. They say that while a person's genes could perhaps cause a weight gain of twenty, thirty, or even ?fty pounds, there's no way someone's genetics could cause her to gain a hundred or more excess pounds. The fault for such obesity, they say, falls on the eater's lack of resolve, not her own particular metabolic circumstances. Not true, and you need only to look at the growing ranks of the obese over the last seventy years to douse such thinking.
As Dr. Fielding likes to tell it, if you had said to your thin, tough grandparents in 1935 that they would be able to sit in their car, make the window go down with a ?ick of a ?nger rather than with a hand crank, and have a nice teenager hand all their grandchildren ?ve thousand calories through the window with none of them making a single move, they'd have told you to stop dreaming. That is, seventy years ago, constant availability of very high-calorie food with no need to expend any calories in order to procure that food was inconceivable, and there were extremely few obese people.
What has changed in the last several decades is not people's level of willpower but our food supply, which has literally become toxic. It's now nothing, as I know intimately, to buy an 1,100-calorie pecan bun from Cinnabon's, an 850-calorie Taco Bell taco salad, a 600-calorie king- size fries, a 400-calorie slice of pizza topped with pepperoni, or a 1,200-calorie pint of superrich ice cream. And there are no more scheduled mealtimes around the table to cue you about when eating starts and when it's over. It's all grazing, all the time. Furthermore, it is more common now to overeat for emotional reasons.
It's at the intersection of these changes that the genetic differences come in. Some people can eat whatever they want whenever they want with no consequences on the scale, or at least not severe consequences. Their metabolic wiring allows them to burn calories faster. Or they may have hormones that are set in such a way that they simply do not get as hungry as other people or as turned on by the sight of food. Others, like me, are not so fortunate. And the not-so-fortunate number keeps growing, because as the food supply keeps getting more and more abundant and concentrated in calories (not to mention more available at every turn), more and more people's genes and metabolisms are losing the ability to withstand the caloric onslaught. Their internal signals are overridden.
In 1980, 15 percent of Americans were obese; now it's more than 30 percent. What has changed is the food, along with the drop in the number of calories people burn in daily activities -- not their characters, genes, willpower, or anything else.