REPROGRAM YOUR METABOLISM

WHEN I WAS A KID, my father was the fattest person I knew. He was 6 feet tall and about 250 pounds, which would’ve made him the size of an NFL lineman of that era—the early 1960s. If anything, he was proud of his girth. He boasted, “The Marines taught me how to eat,” and he spent the rest of his life acting on that knowledge.

Still, it took real effort for a guy to inflate the way my father did. My mother believed he worked harder at eating than he did at his job.

Back then, the average American man in his 30s weighed 170 pounds, so people noticed someone my dad’s size. Even in 1980, after we’d joined the same gym, I can remember a conversation with a trainer who said “that guy Gary” was the fattest person he’d seen in a health club. I was one of the skinnier guys, so he didn’t realize he had just described my father.

Today you wouldn’t notice a man of my father’s weight or girth—not when a typical guy in his 30s now weighs 196 pounds. You probably know a few people who would make my dad look svelte. Maybe you’re one of them. A lot of us know from sorry experience that the classic weight-reduction formula—exercise more, eat less—works in the short term, but the fat typically comes back. Sometimes a double chin redoubles, just to show you who’s in charge.

Human metabolism is a complex system that evolved to keep our weight stable in times of both abundance and famine. How did it devolve into a coin toss where the choices are “heads, you gain weight” and “tails, you gain even more”?

For many, the problem is a condition called metabolic inflexibility, a bit of complicated science that points the way toward simple diet, exercise, and lifestyle modifications—modifications that can help you become lean and stay lean. But before we dive into the deep end of weight-loss research, let’s take a quick detour and look at the reasons the single-generation rise in obesity shouldn’t have happened. We’ll then see how it did happen, and finally we’ll reach the important part: how you can seize your own metabolic destiny and steer it toward skinny.

WHY WE CAN’T EAT JUST ONE ANYMORE
From the early 1900s—when obesity was so uncommon that people lined up to gawk at the “fat lady” in circus sideshows—until the 1980s, our per-capita food supply stayed more or less the same.

We could’ve eaten more food back then. We just didn’t crave it as we do now. Consider everything that happens when you eat a normal meal.

• The food you eat becomes progressively less appetizing. No matter how good the first few bites of that steak might be, by the end you’re just going through the motions.
• Your stomach expands, sending chemical messages to your brain, asking it to stop eating.
• Your metabolism cranks up as your body works to move the food through your digestive system, burning off 10 percent of the calories you just ate.
• Over the following hours and even days, your body monitors your energy balance—the amount of calories coming in and going out. Eat more than you need and you’ll compensate with a faster metabolism—or by burning more calories through physical activity, or by producing more hormones like leptin, which lowers your appetite.

These mechanisms also work in reverse. Should you eat less than you need in order to maintain your current weight, your metabolism slows down to preserve energy, and hunger hormones like ghrelin tick up to increase your appetite.

The goal of this complex system is to hit a balance, at which point it’s hard to gain or lose weight. Only powerful stimuli can override this system, to literally alter your metabolism so it can’t respond the way it should.

Enter your main adversary: the modern food industry, which is to nutrition what lobbying is to Congress—a sure way to twist a good system into one that runs counter to everybody’s best interests.

When Lay’s potato chips introduced the famous slogan “Bet you can’t eat just one” in the early 1960s, the company knew what it was talking about. Its food scientists were in the process of snipping the brake lines on our appetites, and as a society we began running stop signs that had existed for centuries. The food scientists found ways to combine sugar, salt, and fat so that “enough” was never actually enough. If we have a little, we want a lot. Our metabolism wasn’t prepared to counteract the hedonic reward of these new foods or the quantities now available. The food manufacturers ramped up food energy production to 3,900 daily calories per person, enough to put most of us at the “who shrunk my seat belt?” end of the body-weight range.

“Food stimulates many parts of the brain, including regions associated with reward,” says Stephan Guyenet, Ph.D., a postdoctoral research fellow at the University of Washington and the author of a terrific blog about metabolism and weight control, at wholehealthsource.com. “By stimulating those reward pathways directly, you can have a profound impact on food preference and body fat. Manufacturers are trying to maximize the reward.” The upshot, he says: “We’re awash in food that’s easily available, energy dense, highly palatable, and highly rewarding. Commercial food overstimulates those connections in the brain.”