July 29, 2025, 2:02 am | Read time: 5 minutes
On social media, magazine covers, and in ad campaigns, we regularly encounter the toned bodies of people over 40–seemingly effortlessly in top form. Whether it’s action star Jason Statham, actress Halle Berry, or Jennifer Aniston, they all show that a fit and defined body is achievable even in middle age. However, amidst all the inspiration, it’s important to remember that many of these celebrities have access to a team of personal trainers, nutritionists, and chefs. The question remains: Can people without VIP support still be fit, strong, and capable over 40, or does age increasingly get in the way?
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The Myth of a Sluggish Metabolism After 40
The persistent belief is that metabolism slows down from around the mid-20s and really drops off after 40. This seems plausible, as the body no longer grows and theoretically should burn fewer calories. It would also explain why we gain more weight as we age, even though we feel like we’re eating the same amount. But these assumptions are actually incorrect.
In a meta-study, researchers analyzed data from over 6,600 people from 29 countries, ranging in age from eight days to 95 years.1 The surprising finding: By around age 20, a person’s basal metabolic rate–the number of calories the body uses to maintain vital processes–stabilizes. Contrary to expectations, the basal metabolic rate doesn’t decline in midlife but only starts to decrease from age 60, and even then, the slowdown is relatively minor at 0.7 percent per year.
This means your metabolism is relatively stable between ages 20 and 60. Ideal conditions, then, for losing weight and building muscle even after 40.
Hormonal Changes
It’s widely known that hormone levels change throughout life. Women, in particular, likely notice it more–through menstruation and later in life through menopause. Unlike women, men don’t experience menopause, but they do notice changes in their hormone levels, often marked by a significant drop in performance and reduced libido. But what impact do hormones have on the fitness of those over 40?
For Men
The fact is that from around age 30, men’s testosterone levels gradually decline. Since the male sex hormone testosterone is partly responsible for muscle building and performance, a very low testosterone level can negatively affect fitness. If men feel lethargic, have less muscle strength, and lower libido, they should have their testosterone levels checked by a doctor.
Only if a low testosterone level is proven and causing distress can a doctor prescribe medication if needed. This could address the deficiency. However, testosterone replacement is controversial. According to the National Association of Statutory Health Insurance Physicians (KBV) and study evaluations, there is no evidence that these medications extend life, significantly improve sexuality, or enhance fitness and health. Even in a study with men over 60, only a slight improvement in fitness was observed after three years of testosterone replacement.2
The KBV points out that testosterone replacement can have side effects, such as blood thickening with thrombosis risk, elevated blood fats, headaches, prostate issues, breast swelling, mood swings, and high blood pressure.
Also interesting: Are fast or slow repetitions more effective for muscle building?
For Women
For women, hormone levels often change in their early 40s. In the so-called premenopause, the ovaries slow hormone production, leading to an estrogen imbalance. Menstruation can become irregular, more intense, or longer-lasting. This is accompanied by symptoms like nervousness and irritability, decreased performance, hot flashes, depressive moods, sleep problems, and loss of libido.
But there’s good news: Women who engage in light or intense exercise experience less severe symptoms during premenopause and menopause compared to those who are not physically active.3
Regular exercise also leads to higher testosterone levels in men.4 Experts even recommend strength training, especially from midlife, to prevent age-related muscle loss. For health reasons alone, staying fit after 40 is essential.
How Aging Affects Male Genitalia
7 Signals for Men Over 40 to Check Their Testosterone Levels
Long-Term Study Shows: It’s Never Too Late for Exercise
This study is remarkable: There are 30 years between the first and second examinations of the participants. In 1966, five 20-year-old men in Dallas, USA, underwent a comprehensive physiological examination.5 They were then prescribed three weeks of bed rest. The results afterward were alarming: a faster resting pulse, higher blood pressure, and a complete decline in overall fitness. This was followed by an eight-week endurance training phase, and the participants regained their full fitness.
The same men were examined again 30 years later, now around age 50. They underwent another training program. After six months, they had lost weight and had lower blood pressure. They also had similar fitness levels to when they were 20 years old and started the study. Based on the study results, researchers recommended walking, cycling, and jogging to help people stay fit even in older age.
But Strength Training Shouldn’t Be Neglected
An international study has shown that men over 45 may have a link between muscle mass decline and increased health risks.6
“Throughout the study, it became clear how important it is for middle-aged men to lose as little muscle mass as possible to minimize the risk of cardiovascular diseases,” concluded the study’s lead author, Stefanos Tyrovolas.
Conclusion
In conclusion, if you’re over 40 and neither have the ambition nor the discipline to train for a six-pack, you should still stay fit and exercise–for health reasons alone! There are no good excuses from a scientific perspective.