If you want to change your weight, there's good news: your metabolic rate isn't fixed for life. Metabolism can and does change over time, and you can take steps to speed it up or slow it down. If you intend to start gaining weight, see your doctor before you begin to hammer out details of a healthy plan to follow.
As you get older, your basal metabolic rate, or BMR, naturally slows down (see Ref 2). Most middle-aged and elderly people need at least several hundred fewer calories per day than they did in their early adulthood, as they are no longer as active and their body compositions have changed. Aging also brings on sarcopenia, a natural and gradual loss of muscle mass.
A pound of muscle burns more calories at a resting heart rate than a pound of fat (see Ref 2), so losing muscle mass – whether due to sarcopenia, a sedentary lifestyle or other factors – results in a slower metabolism and eventual weight gain. Regular exercise, however, has significant health benefits and is worth keeping up even if you want to gain weight. To keep from building up lots of muscle, focus on low- or moderate-intensity cardio exercise, like treadmill jogging or biking. When you lift weights, use light weights and do just one or two sets per exercise (see Ref 3).
It sounds like a paradox, but severely cutting calories can actually end up slowing your metabolism and encouraging weight gain over time. According to nutrition researcher and board-certified family physician Joel Fuhrman, M.D., calorie restriction slows BMR (see Ref 1). That's one reason why some people on diets seem to reach a "plateau" – as you lose weight, your body needs fewer calories and you burn fewer calories. Since calorie restriction is likely to result in initial weight loss, work with your doctor before trying it if your eventual goal is to sustainably put on weight.
Much like cutting calories, the notion of skipping meals to gain weight may seem counterintuitive. But according to Columbia University, skipping meals slows metabolism and can put the body into "starvation mode," where it works to conserve energy rather than burn it (see Ref 5). Evelyn Tribole, author of "Eating on the Run," points out that skipping a meal is also likely to encouraging overeating at the next meal (see Ref 4). Since skipping meals has health risks, a smarter weight gain strategy is to eat more calories throughout the day and space them out evenly.
- Dr. Fuhrman: Slow Metabolism Linked to Longevity
- Weight Watchers: Aging and Metabolism
- American Council on Exercise: When Strength Training, Is It Better to Do More Reps with Lighter Weights or Fewer Reps with Heavier Weights?
- Human Kinetics: Skipping Meals Can Have Negative Consequences
- Columbia University: Will Skipping Breakfast and Lunch Lead to Weight Loss