April 3, 2012

Healthy Weight Loss

The Healthy Guide to Lasting Weight Loss

It turns out that how you go about slimming down has a profound impact—all too often negative—on your chances of success. The latest findings offer some clearer-than-ever guidelines on how to sort fad diets from healthy, sustainable ways to achieve your best weight.

So what’s the message for women ­trying to lose weight?” asks ­Marcelle Pick, nurse practitioner and author of The Core Balance Diet. “That you’re doomed, and—good luck?” Pick thinks the story is more nuanced and not as grim as all that, but she’s not surprised when ­people are disheartened, particularly in the wake of a study published last ­October in The New England Journal of ­Medicine, the ­latest and most telling blow against the ­notion that American women in their ­twenties, whose average weight climbed about 30 pounds from 1960 to 2000, could slim back down with just a little more will­power. In that study, conducted at the Univer­sity of Melbourne in Australia, subjects who lost more than 10 percent of their body weight experienced a corresponding change in ­crucial appetite-regulating ­hormones such as leptin—and they ­never returned to normal levels during the remainder of the yearlong research period.
Why is that such a big deal? Produced by fat cells, leptin tells your brain’s hypo­thalamus whether your body’s energy reserves are sufficient. Low leptin signals that you need to build up your fat stores, and your brain orchestrates a response—“I’m hungry!”—to compel you to regain weight, even if that’s the last thing your conscious mind wants as you endeavor to maintain post-diet weight loss.
Or consider a study that will likely come out later this year. Eric Ravussin, PhD, a leading weight researcher at the Pennington Biomedical Research Center in Baton Rouge, Louisiana, measured the contestants on TV’s The Biggest Loser and found their leptin levels to be in the tank (six had levels that didn’t even register on the standard measurement test)—which means the odds are their hunger pangs will be so intense that they’ll qualify for The Biggest Regainer in a few years.
The physiological affront is actually a one-two punch. After significant weight loss, not only does our hunger increase but our metabolism slows, so we hold on that much more tightly to each calorie we consume. Researchers at Columbia University have found that people who, like those in the Melbourne study, lose at least 10 percent of total body weight burn 300 fewer calories a day on average than they did before the weight came off. (No one has looked at the metabolic effects of milder weight loss.) So at the same time that your brain is ordering you to eat more, you must eat less to maintain that slimmed-down physique. The woman who goes from 170 to 130 pounds through assiduous dieting and exercise may look just like her friend who’s always weighed 130—same shape, same percentage of body fat—but inside, her “fat brain” is still doing everything in its power to send her body back to Fatville. Hence the dirty not-so-little secret of weight loss: It’s not that hard to lose weight—motivated dieters do it all the time—butmaintaining that loss is a bitch, with success rates as low as 2 percent or as “high” as 20 percent, depending on which studies you choose to believe.
The enemy here is summed up in the concept of the “set point”: simply put, the weight, give or take a few pounds, that your body wants to be. If you drop below your set point—by more than 10 percent, anyway—it will “defend” itself by increasing your ­hunger and lowering your metabolism, which leads to your feeling cranky, chilly, sluggish, and food-obsessed. (In the classic set-point experiment done during World War II, male volunteers at the Univer­sity of Minnesota endured a semi­starvation diet for the better part of a year. How did this regimen affect them behaviorally? Mostly they sat around complaining and sharing favorite food fantasies.)
The precisely wrong way to go about ­losing weight, then, is to dive right past your set point by shedding weight quickly, cutting back calories to a level you ­simply can’t tolerate for the long haul, and ­setting yourself up for the near-inevitable regain. This sad set-point saga is repeated over and over again in New York Times ­reporter Gina Kolata’s 2007 book, Rethinking Thin, as she chronicles the failed (and, in fact, apparently doomed) efforts of four deter­mined dieters to keep off the weight they’ve succeeded in losing.
Indeed, in a new book out this January, Why Women Need Fat, coauthor ­William Lassek, MD, an epidemiologist at the University of Pittsburgh, goes so far as to ­argue that not only do people end up yo-yo dieting ­because they gain everything back, but that yo-yo dieting itself is a main ­reason why American women are, on aver­age, 20 pounds heavier than their Euro­pean counter­parts. Analyzing a ­number of studies, Lassek found that women who frequently diet are heavier than those who never bothered in the first place.
“The tragedy of dieting is that the more you diet,” Lassek soberly concludes, “the heavier you become.” Whether yo-yo dieting is actually worse than doing nothing is far from a settled question in the field, but Lassek explains his position with elegant set-point logic: After enduring a series of strict diets (which to some degree mimic the famines in our evolutionary history to which our bodies, the theory goes, ­developed metabolic survival responses), your body ends up demanding greater fat reserves to buffer itself against whatever undernourishment might be coming next.
But back to Marcelle Pick’s question. Is shedding ­unwanted pounds completely ­hopeless? No. Even Lassek believes that if you under­stand your set point, you can work within its range to achieve the best weight you’re ­capable of maintaining—­becoming somewhat less heavy and considerably more healthy. (Those who have it hardest are the rela­tively few who are genetically programmed to be obese; this group faces a seriously uphill battle, though one that can be won, Lassek and other experts believe.)
The first obstacle we face, however, is that, constantly tempted by high-­calorie snacks and junk-food meals, many of us have lost sight of the lowest set-point weight that our genes will readily allow us to ­sustain; a more accu­rate term for where we end up, suggests Ravussin, is a ­“settling point”—the weight that our genes and ­current lifestyles (which is to say, our ­habits of diet and exercise) conspire to ­defend. He points to his study of Pima ­Indians. Pimas who retain a traditional way of life and cuisine in Mexico are still lean and fit, but their genetically near-­identical North American cousins have found a new ­settling point—and an alarming inci­dence of obesity—courtesy of fattier foods, refined carbohydrates, and a more sedentary lifestyle. (In his 2009 book, The End of Overeating, former FDA commissioner ­David Kessler, MD, essentially accuses the food industry of hooking us on cheap-to-produce processed foods high in fat, sugar, and salt. He suggests an exercise to relocate our real hunger level: Cut back your meal portions by half, then see how you feel 30 minutes and then 90 minutes after eating.)
I can come up with an example closer to home. Some 25 years ago, my sister-in-law, Naomi Moriyama, left her native ­Japan to finish college. When she returned home after two years of living and eating like an American coed, her family was shocked to see she’d added more than 25 pounds to her compact 5'2" frame. She went back to eating the way she always had—lots of fish and veggies, smaller ­portions, far less junk food—and the weight dropped off in a ­matter of weeks, an experience that she put to good use in writing her 2005 book, Japanese Women Don’t Get Old or Fat.
On the other hand, my wife, Kate, a sixth-­generation Irish-American, was dealt those hang-on-to-the-last-­potato genes. Unless she pays undying ­attention to what she eats and how much she exercises, the ­unwanted weight piles on, her ­hormonal and neural circuitry a one-woman hunger museum. Moriyama’s ­settling point was temporarily thrown out of whack because of a lifestyle change; Kate does battle with her physiological set point on a daily basis.

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