With age, muscle mass gradually decreases, and with it — calorie expenditure
After 30, many people notice an unpleasant pattern: the diet is the same, they’re still active, but the weight keeps creeping up. Diets that used to work in a couple of weeks now barely produce results. In 2025, endocrinologist and nutritionist Oksana Mikhaleva explained what happens to the body after 30 and which approach to weight loss actually works at any age.
Why People Gain Weight After 30
The first thing people think about when facing weight gain is thyroid problems. It’s a logical suspicion, but according to the endocrinologist, in most cases the thyroid has nothing to do with it. She said that the real reason is a decrease in metabolism — the rate at which the body expends energy.
Metabolism slows down because with age, a person gradually loses muscle mass. Muscles are the main “consumer” of calories in the body. The more muscle you have, the more energy the body burns even at rest. The less muscle — the fewer calories are expended, and everything “extra” gets stored as fat.
Think of a car engine. A big engine consumes more fuel, even when idling. Muscles work on the same principle: the more you have, the more calories the body “burns through” simply to sustain life. When muscle mass decreases, your “engine” becomes more efficient — and what used to burn off now remains as fat stores.
Why Muscles Weaken With Age
Two types of hormones directly influence muscle maintenance: growth hormone and sex hormones, primarily testosterone. These are the ones that help the body build and maintain muscle tissue.
The problem is that growth hormone production begins to decline as early as age 30. Hormonal changes occur differently and at different times in women and men, but the overall trend is the same: the older a person gets, the less hormonal support their muscles receive.
By the way, this is exactly why men usually find it easier to lose weight. Their testosterone levels are significantly higher than women’s, which means more muscle mass and a higher basal calorie expenditure. This isn’t a matter of willpower — it’s physiology. But testosterone declines with age in men too, so the problem of weight gain eventually affects everyone.
Why It’s Harder for Women to Lose Weight
For women after 30, losing weight is objectively harder, and it’s not about laziness. Women’s testosterone levels are already low, and they decrease even further with age. Growth hormone also drops. As a result, muscle mass is lost faster, and fat tissue accumulates more easily.
On top of this, there’s another factor the endocrinologist mentions: physical inactivity. According to her, more than 70% of the population (and possibly up to 90%) have insufficient levels of physical activity. This is especially true for older people. In other words, muscles not only lose hormonal support but also stop receiving the exercise that could compensate for these losses.
It’s a double blow: fewer hormones, less movement — muscles waste away, metabolism drops, weight increases.
How to Lose Weight After 30
The good news is that age-related weight gain is not a life sentence. According to Mikhaleva, both women and men can maintain a normal weight at any age. The recipe isn’t new, but it’s the only one backed by practice: physical activity plus calorie control.
Specific recommendations from the endocrinologist are as follows:
- Baseline activity level — about 10,000 steps per day;
- Additionally — at least 150 minutes per week of moderate or high-intensity physical exercise (that’s roughly 30 minutes five times a week);
- After age 40 — reduce daily calorie intake by 100 kcal compared to younger years;
- After age 50–55 — another minus 100 kcal (totaling 200 kcal less than at age 25–30).
Note: this isn’t just about walking or cardio. Strength training is especially important for maintaining muscle mass — it’s what stimulates muscles to grow and prevents them from “melting away” with age. 150 minutes per week is the minimum, not the limit.
Why Diets Don’t Help You Lose Weight After 30
Many people try to lose weight solely by restricting food. In youth, this sometimes works — metabolism is still high, muscles are intact. But after 30, a strict diet without physical exercise can have the opposite effect: the body starts burning not only fat but also muscle. And the less muscle you have, the lower your metabolism — and the faster the weight comes back once the diet ends.
This is precisely why the endocrinologist emphasizes not diets but lifestyle: sufficient activity, moderate calorie reduction with age, and maintaining muscle mass. It’s not a quick result in a week, but it’s an approach that truly works in the long run.
The conclusion is simple: after 30, it’s harder to lose weight not because something is wrong with you, but because the body loses muscle and expends less energy. The only reliable way to compensate for this is to give your muscles work and avoid overeating. No magic, but no deception either. The body obeys physics: if you expend more than you consume and preserve your muscles, your weight will be under control at any age.
