For Better Health, Trim Weight-Loss Goals
As the season of turkey and eggnog approaches, let’s dispel some myths about dieting.
The good news is that most Americans do not pack it on during the holidays. On average, we gain about a pound between November and December, according to a study published in the New England Journal of Medicine in 2000. The bad news? Many of us are too heavy even before that first mug of eggnog, and it doesn’t get much better despite the New Year’s resolutions.
What is more, the vast majority of people who lose a lot of weight eventually regain just about all of it. This stark fact underscores how far we remain from conquering the obesity epidemic spreading across the Western world. It also underscores a need to be more realistic about the achievable goals and benefits of weight loss.
Why is it so hard to keep the weight off? The reason is both simple and complex. Gaining a significant amount of weight — we don’t know exactly how much — doesn’t just puff up our fat cells; it changes our biology. Our bodies act as if that higher weight is our normal weight, defending it like a mother embracing her newborn.
First, our metabolisms slow, so we must eat even less not to gain weight. For example, a study of contestants on the TV show “The Biggest Loser” found that before the competition, they had an average resting metabolism rate of 2,607 calories per day. After the show, it was 2,000 calories. Six years later, most had returned to their pre-show weight, while their resting metabolisms had dropped to an average of 1,900 calories per day. At the same time, our bodies barrage us with hormonal signals saying we are hungry all the time, an inner voice chanting “eat, eat, eat!”
In effect, with significant weight gain, our bodies become our enemy, undermining our efforts at every turn.
Just how hard it is to keep off lost weight was underscored last year by seemingly happy news about the effectiveness of gastric bypass surgery. Researchers at Duke University found that 10 years after surgery, almost three quarters of the obese patients had maintained weight loss of more than 20 percent of their pre-surgery weight. For a person weighing 300 pounds that means a sustained weight loss of 60 pounds. (Less encouraging results were found for those who had a sleeve gastrectomy or adjustable gastric banding.)
But this study does not herald the discovery of the mythical magical bullet (or scalpel). Most patients in the study, who started with average body mass index of 47, are still considered obese (a BMI of 30 or above). They do not have the chiseled bodies promised in magazines and strived for on reality programs like “The Biggest Loser.” However encouraging, this study offers yet more evidence of the immense challenges faced even by those who undergo the radical step of surgery to address their weight.
The good news is that, thanks to groundbreaking obesity research conducted during the last few decades, we now know why it is so hard to sustain weight loss. Since the 1980s, when most scientists thought fat cells were inert storage vessels, we have discovered that they are in fact engines in a vast and complicated network, which interacts with the brain to control hunger, metabolic rates, and other key functions.
Unfortunately, these insights into how our bodies work have not led to reliable interventions to control them. This suggests two lessons. First, people do not regain weight because they lack willpower. Instead, their best efforts are countered by powerful biological responses that fight them at every turn. The second lesson comes from my University of Michigan colleague, Dr. Charles Burant: “Don’t get heavy in the first place.”
That’s easier said than done, of course. But Dr. Burant’s insight suggests a radical and necessary new way of viewing obesity. Although most people know how hard it is to lose and keep off weight, our culture still casts obesity as a typical health condition — a problem that can be cured through the relatively simple treatment of diet and exercise. Obesity is better understood, instead, as a chronic condition that we help bring upon ourselves. Once we let it happen, it is almost impossible to reverse. You’d think the stakes couldn’t be higher.
And yet, they are. Research suggests that a mother’s weight and eating habits before and during pregnancy can affect the genes that control weight. The resulting picture is not entirely grim, however. We are also finding that a little weight loss provides a lot of health benefits. Obese people who lose even 10 or 20 percent of their body weight usually enjoy meaningful reductions in blood pressure, blood sugar levels, and inflammation. They also report feeling much better both physically and mentally.
Although surgery is effective, our weight management program at the University of Michigan is also helping obese patients lose and keep off 10 percent of their body weight without going under the knife. That result — which can have measurable health benefits — is hard won, and is achieved through a rigorous program of diet, exercise, and counselling. Both in this program and in our bariatric surgery program, we are seeking clues that will enhance our ability to prevent weight gain as well as more reliably help with weight loss.
The science of weight is ongoing. But we do know two things for certain. First, obese people should focus on how they feel instead of how they look. Realistic goals can provide lifesaving benefits. Second, we need to pay greater attention to people who are not overweight. For them the advice is similarly clear: be vigilant; watch your weight. Take action when you have gained five pounds. By the time it gets to 50, it will be much harder, if not too late.
Marschall S. Runge is Executive Vice President for Medical Affairs and Dean of the Medical School for the University of Michigan.