If you're looking to lose weight, hitting the gym probably tops your list of priorities, but study after study shows that a laser focus on exercise doesn't result in weight loss. Confusing, right? That's why Vox reporters took an in-depth look at more than 60 studies on weight loss and obesity. Here's what they found:
- Exercise alone is almost useless when it comes to losing weight. Researchers tracked people who added more workouts to their training schedules but kept their diets the same and found they lost only a few pounds. Our energy system is a lot more complicated than calories in versus calories out, so it's hard to create a calorie deficit just with exercise. Predicting adult weight change in the real world: a systematic review and meta-analysis accounting for compensatory changes in energy intake or expenditure. Dhurandhar EJ, Kaiser KA, Dawson JA. International journal of obesity (2005), 2014, Oct.;39(8):1476-5497.
- Exercise accounts for a small percentage of our daily calorie burn. Fewer than 30 percent of the energy we expend comes from exercise. Physical activity and physical activity induced energy expenditure in humans: measurement, determinants, and effects. Westerterp KR. Frontiers in physiology, 2013, Apr.;4():1664-042X. We burn more calories doing everyday things like breathing and digesting.
- Exercise can undermine weight loss. We've all told ourselves that we deserve that margarita or slice of pizza because we went to spin class earlier. In other words, working out can make you eat more, either because you think you burned off a bunch of calories or because you're actually hungrier. Your body may even conserve energy after exercising to try to hang onto fat for future energy needs. The response to exercise with constant energy intake in identical twins. Bouchard C, Tremblay A, Després JP. Obesity research, 2006, Apr.;2(5):1071-7323.
Predicting adult weight change in the real world: a systematic review and meta-analysis accounting for compensatory changes in energy intake or expenditure. Dhurandhar EJ, Kaiser KA, Dawson JA. International journal of obesity (2005), 2014, Oct.;39(8):1476-5497. (Wow! Thanks, body.)
- More exercise doesn't mean more calories burned. This theory is still being tested, but scientists found evidence that after a certain amount of exercise, you stop burning energy at the same rate. So logging double the steps on your Fitbit doesn't necessarily mean you burned double the calories.
So what does work for weight loss? The National Weight Control Registry, which studies adults who have lost at least 30 pounds (and kept it off for more than a year), says the best strategies are weighing yourself weekly, watching your portion size, staying away from high-fat foods, restricting your calorie intake, and exercising regularly. And if you're incorporating both diet and exercise into your weight-loss plan, don't count the calories you burn on the treadmill as negative calories.
It's also important to remember that these suggestions are for an average person, which doesn't take into account your personal health history. If you're serious about losing weight, talk to a primary care doctor or nutritionist and create a plan that's best for you.