It’s usually not just due to losing muscle mass over time (more on that later). "It's multifactorial," says Fatima Stanford, MD, MPH, obesity medicine physician scientist at Massachusetts General Hospital and Harvard Medical School. Numerous factors can sneak up on you and help you gain or hold onto weight, including your lifestyle, your food, your biology, and your sleep habits. The good news in that is that there are also numerous ways to tackle getting your weight to where you want it—you don't have to force yourself into one approach, and you get to choose what works for you.
When you were young, you probably didn't spend too much time thinking about preparing your body for the future. In your teens and twenties, you're in peak condition and it's the perfect time to start exercising. Cut to 20 years later and, if you didn't start exercising, you probably wish you had since there's something we all start to experience in our 40's—weight gain.
Additionally, attempts to lose weight on low-calorie diets can lead to even more lost muscle. Studies have found that regular resistance or strength training may be a better alternative than your daily runs to preserve and gain muscle — even when coupled with a low-calorie diet. Aerobic exercise is still important, just don’t make it your only form of activity.
Amy Myers, MD is a two-time New York Times bestselling author and an internationally acclaimed functional medicine physician. Dr. Myers specializes in empowering those with autoimmune, thyroid, and digestive issues to reverse their conditions and take back their health. In addition, she is a wife, mother, and the successful founder and CEO of Amy Myers MD®.
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