Metabolism After 40: What Really Changes—and What You Can Do About It

By Lizzie Streit, MS, RDN, LD

Working towards weight loss after the age of 40 presents different challenges than you may have experienced in your 20s and 30s. You may feel that you’re eating the same meals and exercising similarly but that the number on the scale creeps upward much more easily. If you’re in this boat, rest assured that it’s very common.

It’s also common to attribute the increasing difficulty to lose weight after 40 to a slow down in metabolism at this age. However, current research suggests the reality is more nuanced.

Keep reading to learn why maintaining weight suddenly seems harder in middle age and what you can do about it.

1 - With age comes muscle loss.

The idea that metabolism slows down in your 40s stems in part from the fact that muscle mass begins to decline in your 30s and 40s. Since muscle is metabolically active, having less of it translates to lower energy needs. Muscle tissue also plays a role in glucose metabolism, vitamin D absorption, and inflammatory processes in the body, all of which may affect weight status and health if muscle is not maintained.

To prevent age-related losses in muscle mass and the related metabolic side effects, make resistance and strength training a priority and consume adequate protein. Engage in weight lifting or bodyweight exercises like pushups and squats at least twice a week, and aim to eat 25 to 30 grams of protein per meal.

2 - Your lifestyle has changed.

For many people, life at 25 provides many more opportunities to move throughout the day than life at 45. You may no longer be playing in the pickup soccer league you did in your 20s, chasing after toddlers, or devoting as much free time to exercise. At the same time, you may be experiencing more stress and worse sleep due to career demands, aging parents, or parenting teenagers.

If you’re still eating the same way you did in your 20s, while moving less and having less muscle, focus on dietary changes to start. Prioritize protein at meals, limit mindless snacking, have smaller portions of desserts, and add fiber-rich carbohydrates to every meal. If meal planning and preparation is a challenge, consider healthy diet meal delivery like Healthy For Life Meals. At the same time, look for opportunities for more movement, such as taking the stairs, having walking meetings, and suggesting active outings when meeting up with friends.

3 - Hormones change where your body stores fat.

Women over 40 may be particularly impacted by hormones and their effect on weight maintenance. Hormone changes, including declining estrogen levels during menopause, are associated with weight gain and a greater accumulation of abdominal fat.

If you’re experiencing perimenopause or menopause, make strength training a priority. This type of exercise has been shown to improve body composition. In addition, prioritize protein at every meal to maintain lean muscle and stay full between meals. Choose chicken breast, low-fat Greek yogurt or cottage cheese, fish, tofu, beans, or lentils.

Look beyond calories and protein, too.

Calories and protein are important, but they aren't the only things to consider when choosing foods—especially if prepared meals are a regular part of your routine. Fiber, saturated fat, sodium, and overall nutrient balance matter, too. Taking a closer look at nutrition information can help you understand what you're actually getting from the foods you eat and make choices that support your overall health.

Weight loss struggles after 40 are common and stem from a variety of factors. Fortunately, there’s a lot you can do to get healthy. Instead of getting too caught up in trying to “speed up” your metabolism, focus on preserving muscle, staying active, eating enough protein, and prioritizing sleep.

Healthy eating after 40 doesn't have to mean spending more time planning, shopping, and cooking. Healthy For Life Meals provides nutritionally balanced, fully prepared breakfasts, lunches, and dinners to make staying on track easier—even when life gets busy.

No cooking. No tracking. No guesswork.