Just because obesity might run in your family doesn’t mean your size is set in stone.
You may get your smile and quick hand-eye coordination from your mom, and your hair color and demeanor from your dad—but is your weight genetic, too, just like these other traits?
If you’ve been struggling with your body composition (because it’s really about that, not weight)—and your family does, too—it might be easy to blame weight or obesity on genetics. But do your genes really destine you to be one of the 33 percent of Americans who are overweight or the 38 percent who is obese?
Turns out, the answer is no, but there is mounting scientific evidence of a tipping point where losing weight—and keeping it off—gets a heck of a lot more difficult.
Weight and Genetics 101
While hundreds of genes affect weight in small ways, several known mutations run in families and appear to predispose people to obesity. (These mutations are not routinely screened for, so don’t expect your doctor to uncover them in your annual blood tests.)
For example, someone who is genetically predisposed to gaining weight is going to have a harder time controlling hunger—some of the genetic mutations involve resistance to the hunger-suppressing hormone leptin—and a harder time losing weight once it’s gained than someone without that genetic makeup.
That said, how your genes express themselves may be largely up to you. “The genetics of obesity is not well understood,” says Howard Eisenson, M.D., 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. That means, even if you possess genes that predispose you to be a higher weight, it’s in no way a done deal. “Just because someone has a lot of obesity in their family doesn’t mean they will inevitably develop it,” says Dr. Eisenson. Even among people who have a genetic tendency toward obesity, there are people who remain in a lower weight range.
How Genetics Impact Metabolism
It adds up to this: The best way to avoid being overweight is to maintain a healthy weight in the first place. The latest research is uncovering the reasons why once you’ve 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, Ph.D., 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, M.D., a researcher and clinician at the University of Melbourne in Australia. His study, published in the New England Journal of Medicine, suggests that if you lose 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 you crave food. “The body wants to defend that formerly heavier weight you got to, and it has vigorous mechanisms to achieve that,” says Dr. Proietto. 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.
Genetics and Weight Loss
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.
“Everyone in my field now agrees that the aggressive prevention of weight gain is the way to focus our efforts,” says Steven Heymsfield, M.D., 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 is you’re wondering how to lose weight with bad genetics. “Eat right and get some exercise; even if you do those things and don’t lose weight, you will still be healthier,” says Dr. Heymsfield. (Because, reminder, weight doesn’t equate to health status.)
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,” says Frank Greenway, M.D., an endocrinologist at Pennington Biomedical Research Center. Eating right is key to losing weight, exercise is key to maintaining.
If you haven’t gained a lot of weight, “you don’t have to do as much as someone who has,” says Dr. Hill. “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.”
Larger weight losses can also 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 fuel.
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, Ph.D., 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 Find Your Healthy Weight
If you could use to lose a few lbs to find your happy weight, take inspiration from the National Weight Control Registry, a database that surveys those who have lost at least 30 pounds and kept it off.
- 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.
- Switch to strength training. While there isn’t much data on this, Hill says, it stands to reason that the strength 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. Just getting started? Try this non-intimidating strength-training routine for beginners, or this leveled-up version for more challenge.
- Exercise as close to daily as you can. The workouts of successful slimmers “range from 30 minutes a day to 90, but the average is about 60,” Hill says. (But remember, active rest days are vital, too.)
- 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.
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