Your Genes and Obesity
Oh, please. Just shut up, already.
That's what I have begun to tell myself whenever I catch my mind noodling around with the same thought I've had a half dozen times a day for my entire adult life: I wish I could lose a few pounds.
You see, I'm not fat and have never been more than a little overweight — the freshman 15, too much edible merriment around the holidays, that kind of thing. I'm one of those women, quite possibly like you, who worry when they've put on a couple of pounds, but who usually look perfectly fine — great, even, on a good day, depending on the spandex content of their jeans — and who stay within a healthy weight range. Yes, I exercise a lot and try to eat right, but I'm also lucky — damn lucky. Exactly how lucky, I didn't realize until I reported this story.
The question was, are there some of us who, despite doing almost everything right, are destined to be fat, thanks to our genetic makeup, outside factors that make it tougher to exercise and eat right, or some evil fat-bestowing fairy visiting us while we sleep? Are we going to end up being one of the 34 percent of Americans who are overweight or the 34 percent who are obese, according to the Centers for Disease Control and Prevention, no matter how hard we try?
Turns out, the answer is no, but yo-yoers beware: There is mounting scientific evidence of a tipping point of pudginess after which losing the weight you've gained — and keeping it off — gets a heck of a lot more difficult.
Fat Genes Versus Skinny Genes
While hundreds of genes affect weight in small ways, several known mutations run in families and clearly appear to predispose those who have them to obesity. (These mutations are not routinely screened for, so don't expect your doctor to uncover them in your annual blood tests.) That said, how your genes express themselves may be largely up to you. "The genetics of obesity is not well understood," says Howard Eisenson, MD, the executive director of the Duke Diet & Fitness Center. He points out that research suggests that genetics accounts for 50 to 70 percent of our weight variability, meaning that being fat, even if you're loaded up with the "bad" genes, is in no way a done deal. "Just because someone has a lot of obesity in her family doesn't mean she will inevitably develop it," Dr. Eisenson says.
Yes, someone who is genetically predisposed to gaining weight is going to have a harder time controlling her hunger when she's plunked down in the cookie aisle — some of the genetic mutations involve a resistance to the hunger-suppressing hormone leptin — and a harder time losing weight once it's gained than someone without that genetic makeup. Amy Young,* 33, of Silver Spring, Maryland, has never been tested for an obesity gene, but she may well have one. She grew up with both parents and her two sisters being overweight (although her brother was not). "I would read about dieters who would say, 'I just stopped eating six milkshakes and fried chicken, and I lost all this weight,'" says Young, whose highest weight at five foot five was 280 pounds. "I never did that. I never ate anything fried, and we never had junk food or bags of chips or Oreos." Nonetheless, she and one of her sisters were heavy from childhood. At a weight-loss camp, they shed a considerable number of pounds but promptly packed them back on. "That regain was more traumatizing than being heavy in the first place," Young says. She has since been a patient of Dr. Eisenson's, and while thinner now, she works hard to keep her weight below 200 pounds. She tracks her food, eats 1,800 calories a day (she's a nursing mom), and does a daily hour of cardio as well as working out with a trainer two to three times a week. "I can't do any more," she says.
Young's story stands in stark contrast to Samantha Murphy's. Murphy, who is 30 and also five foot five, weighs about half as much: 104 pounds. She has always been thin, as has her entire family. "I try to have a lot of fruits and vegetables, but I basically eat what I want when I want, sometimes healthy, sometimes not," says Murphy, who lives in Greenwich, Connecticut. She exercises only once a week (although she walks three miles to work) and is a professed chocolate lover who eats it "at least once a day." That's not to say Murphy overeats; to maintain a weight of 104 pounds with little exercise requires eating approximately 1,456 calories a day. She says she gets full quickly and listens to her body's signals to stop eating, perhaps a sign that the hormones that regulate satiety are working well. "It's just the way I am."
Being thin may not come as easily or as naturally to most of us, but even among people who have a genetic tendency toward obesity, there are those who never get fat. "There are lots of different behavioral strategies to losing weight and keeping it off," Dr. Eisenson says. Some of his patients count calories religiously, others cut carbs or fats, some cannot indulge at all, and still others find that the occasional treat prevents splurges. "None of these works for everyone," Dr. Eisenson says. "You have to take a good, hard look at what you're willing to change for good."
*Name has been changed for privacy
Dodge Metabolism Meltdown
It adds up to this: The best way to avoid being fat forever is to not get too fat in the first place. The latest research is uncovering the reasons why once you've been heavy and lost weight, you have to eat less and exercise more to simply maintain your body at a new, lower weight than would someone at the same height and weight who has never been heavy — essentially dieting for the rest of your life just to break even.
This is because the very act of losing weight places your body in a metabolically disadvantaged state — for how long, nobody is sure. Therefore, you need fewer calories simply to stay thinner, even if you're not trying to lose. "There's a penalty to pay for having been obese," says James O. Hill, PhD, the executive director of the Anschutz Health and Wellness Center at the University of Colorado.
You're paying something of a penalty, albeit probably a lesser one, even if you were merely overweight, adds Joseph Proietto, MD, a researcher and clinician at the University of Melbourne in Australia. His study, published in the New England Journal of Medicine, suggests that if a person loses 10 percent of her body weight — going from, for example, 150 pounds to 135 pounds — there is a long-lasting change in the levels of hunger-controlling hormones which will make her crave food. "The body wants to defend that formerly heavier weight you got to, and it has vigorous mechanisms to achieve that," Dr. Proietto says. As soon as you drop your guard, the weight creeps back on because your metabolism is not working as efficiently. That's why losing a great deal of weight and keeping it off happens so infrequently.
"There are only a few Jareds in the world," says Frank Greenway, MD, an endocrinologist at Pennington Biomedical Research Center, referring to the Subway spokesdude who lost 245 pounds and has made a small mint off of his ability to maintain his new size.
An Ounce of Prevention
So right about now you may be despairing that those 15 hard-fought pounds you lost will inevitably boomerang back. But don't give up. Simply knowing that you're going to have to apply yourself consistently is more than half the battle. If you're reading this magazine, odds are you're already on the case, and even if you're not at your dream weight, you're working to not gain any extra pounds. That's fantastic news — the best news in terms of your long-term weight fate, according to each expert I spoke to.
"Everyone in my field now agrees that the aggressive prevention of weight gain is the way to focus our efforts," says Steven Heymsfield, MD, the executive director of Pennington. That's right: The simple fact that you're maintaining your weight, even if it isn't your ideal but is close to a healthy range, is a huge success and will put you ahead of the game. "Eat right and get some exercise; even if you do those things and don't lose weight, you will still be healthier," Dr. Heymsfield says.
These findings gave me a welcome perspective and helped me shift my get-fit goal from "lose 10 pounds" to "just don't gain." Likewise, I'm hoping this story makes you feel good about eating right and working out, because the consensus in the world of obesity research seems to be that those efforts — the ones you're already making — will truly boost your health even when the scale refuses to budge.
Why Big Gains Are a Bad Idea
A few pounds are easier to deal with. "You can lose 5 or so percent of your body weight and with a little effort, keep that off," Dr. Greenway says. Dieting is key to reducing, exercise is key to maintaining.
A cinch in time saves nine. If you haven't gained a lot of weight, "you don't have to do as much as someone who has," says researcher James O. Hill, PhD. "It doesn't take 90 minutes of exercise a day to prevent weight gain, but it may take that much to keep pounds off once you've lost them. It's not fair, but that's the way it is."
The more you have to lose, the more vigilantly you'll have to diet — permanently. Let's say you cut back from 2,000 to 1,500 calories a day. Dr. Heymsfield says that the pounds will come off, but that over the course of a couple of years, as your metabolism slows to conserve weight (and as a lighter person, you're burning fewer calories during any activity), you'll need only 1,500 calories a day to stay the same. Go back to eating 2,000 calories, and the weight returns. Adding muscle helps, but a pound of it burns only about 14 calories more a day.
Larger weight losses make your hormones go haywire. Dr. Proietto's research found that once you lose 10 percent or more of your body weight, the levels of certain hormones, including leptin and ghrelin, get all out of whack and stay that way for an unknown amount of time, so your brain tells you you're hungry even when your body doesn't need the calories.
When you have to maintain a diet for a long time, your mind plays tricks on you. As you first start dieting, says John R. Speakman, PhD, of the Institute of Biological and Environmental Sciences in Scotland, your body is blowing through its glycogen reserve and shedding the weight of the water that glycogen is stored with, so the scale shows a big drop. "Studies in the lab have suggested that if you stay on a diet, the weight loss after this initial drop is pretty steady and doesn't reach a plateau," he says. But in the real world, because weight loss appears to slow down, people tend to lose their resolve and become a little less strict with their diet than in those first weeks, thereby creating an actual plateau.
How to Keep the Weight Off
Lessons from Losers
What are the secrets of those who have lost at least 30 pounds and managed to keep it off? We tapped the National Weight Control Registry to find out.
Freshen up your motivation. "What inspired them to start losing the weight may not be the same as what helps them keep it off," says Hill, who cofounded the registry. A health scare might have prompted the initial loss, for example, but wearing clothes they like might later be the reason.
Tone your muscles. While there isn't much data on this, Hill says, it stands to reason that the weight training these maintainers do is a factor in their ability to stay at their lower weight. "It helps build muscle and prevent the loss of muscle mass, and, of course, muscle burns calories," he says.
Exercise daily. The workouts of successful slimmers "range from 30 minutes a day to 90, but the average is about 60," Hill says.
Tie exercise to something else that's meaningful to you. "One woman said she makes time for spirituality every day, and during that special time, she walks and meditates," Hill says. Many long-term maintainers, he adds, even change careers and become dietitians or trainers.
Weigh yourself regularly. Maintainers weigh themselves daily or every few days and cut back immediately when they eat too much. This is what Hill suggests people at a healthy weight should do simply not to gain. "If you're paying attention now, you won't let your weight creep up," he says.
Originally published in FITNESS magazine, September 2012.