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.
If you eat healthy and exercise regularly and still can’t lose weight, your thyroid might not be working like it should. This happens in about 5% of people, and it's most common in women and people over 60. In addition to weight gain, it can also cause fatigue, joint or muscle pain, and depression. Medications can help, so get it checked if you think it might be an issue.
You may wonder if you should even try to lose weight in midlife. Shouldn’t you just accept weight gain during menopause as part of life? The answer is “No!” While accepting and loving your body is important, achieving and maintaining a healthy weight as you are reaching menopause is not about how you look. Excess weight in later life holds a variety of dangers to your health and well-being.18 Losing excess weight, and especially belly fat, may significantly decrease your risk of a variety of health issues, including19,20:

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.


As you enter your forties, you are also entering perimenopause, when levels of your sex hormones progesterone and estrogen decline. Besides regulating your menstrual cycle and reproductive functions, these hormones also impact restful sleep and relaxation. A decrease in progesterone and estrogen levels may lead to sleep disturbances, restlessness, and insomnia.1 Because changes in sleep patterns have been associated with weight gain, sleepless nights may make weight loss increasingly difficult.2
Unfortunately, you can't just focus on one area of your body. "Women should focus on all muscle groups in order to lose weight and build muscle because there's no such thing as spot training," Diamond reminds. "With that said, women have a tendency to gain weight in the midsection as we age and focusing on the core and a well-balanced workout will help to reshape body composition."
When you’re under-rested, your appetite-regulating hormones get short-circuited, so your appetite goes into overdrive, but the hormones that tell you you’re full don’t kick in promptly. Studies also suggest that when you’re sleep-deprived, it alters the way you think about food, so you have stronger cravings for sweets and other less healthful eats.
Focusing on being healthy means getting about 30 minutes of moderate exercise every day. This level of exercise can keep your heart healthy and work on things like lowering your cholesterol and/or blood pressure. This is a great place to start if you're getting into exercise after a long break. There's no reason you can't start here and progress to more intense goals as you build strength and endurance.
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.
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