If you've ever tried to lose weight and found the pounds won't come off easily — or they come right back — you are not alone.
The fact is that when we shed pounds, we trigger mechanisms that make it hard to keep the weight off. Some factors are within our control, but many are not. Understanding how this works might make you look more kindly on your body.
Here are 5 realities about biology concerning weight loss:
1. Metabolism Slows When You Lose Weight
Your metabolism is the process through which your body converts the food you eat into energy. Metabolism varies from person to person and it slows as we age.
It also varies by gender — men have faster metabolisms because they have more muscle on their bodies. So the more muscle mass you have, the faster your metabolism.
But, when you lose weight and muscle mass, your metabolism slows down. "One way to counteract this slower metabolism is to do more physical activity," Dr. Donald Hensrud, author of the Mayo Clinic Diet Book says. "So if people can increase their activity, it can help to keep the weight off – even if their metabolism is a little bit slower."
Plus, with more physical activity, you're likely to increase muscle mass that you lose from dieting, which should speed up your metabolism and calorie burn.
2.If you choose to try to lose weight, make changes that you can live with for the long haul
If you want to lose weight, you need to think of long term. In other words, make changes that you actually like, because you'll need to stick with them to keep the weight off.
Kevin Hall, senior scientist at the National Institute of Diabetes and Digestive and Kidney Diseases says metabolism seems to act like a spring: The more effort you put into losing weight, the more you can stretch that spring out — that is, lose weight.
But if you let up the tension on the spring — by stopping whatever eating and exercise routine helped you lose weight — your metabolism will spring back and you'll regain the weight you lost. "Your body does persistently fight back and try to make you regain the weight that you've lost," Hall says.
This means that whatever changes you make to your diet or physical activity have to be kept up permanently to avoid weight regain.
3. Hormones in your brain conspire to make you hungrier when you lose weight
Here's another diabolical change that happens when you lose weight: Your hormones change in ways that alter your appetite. While a lot of different hormones are involved in hunger, one of them is leptin, which is released by fat cells and basically tells your brain when to eat and when to stop eating.
As you lose weight, your leptin levels drop, and when that happens, "it's like a starvation signal," Hall says. A lot of times, he says, people "seem to want to eat even more than they were eating before to kind of rapidly recover that weight loss."
4. To lose weight, what you eat is more important than how much you exercise
For most people, exercise is a minor player in weight loss. The fact is that it's a lot easier to cut out 600 calories by skipping a Starbucks muffin than it is to burn it by running for an hour or more.
What's more, people tend to use exercise as an excuse to let themselves eat more. When that happens, they tend to eat more calories as a "reward" than they burned off at the gym. Or they might compensate by crashing out on the sofa and moving less the rest of their day.
But that shouldn't be a reason not to exercise. Just don't do it so you can "earn" a piece of chocolate cake.
5. On the other hand, exercise seems to play a big role in maintaining a lower weight
A lot of what we know about how people maintain weight loss over the long haul comes from the National Weight Control Registry, a database of people across the U.S. who have lost at least 30 pounds and have kept it off for at least a year.
The No. 1 thing these people have in common: They report exercising every day for about an hour on average.
But that doesn't have to mean grueling workouts. The most popular form of exercise among this group is walking, says Dr. Holly Wyatt, an associate professor of medicine at the University of Colorado Anschutz Medical Campus, who studies people on the registry.
She says these long-term weight-loss maintainers also do a lot of resistance training and other activities. "So it's not specifically one activity that's associated with success," Wyatt says. "I think, more than anything, it's the volume of activity."