Hormones and Exercise: How Physical Activity Supports Metabolic Balance

“Genetics provides the biological foundation of our health and cannot be changed, but lifestyle largely determines how that genetic predisposition is expressed. In this sense, physical activity is far from secondary. Nutrition and exercise are the 2 factors that most strongly influence:

• energy balance;
• muscle mass;
• insulin sensitivity.

If nutrition provides the nutrients, exercise helps optimise how the body uses them. Other lifestyle factors, including sleep, stress and sedentary behaviour, can either support or hinder the results.

Overall, even in people with a genetic predisposition to metabolic disorders, those who exercise regularly tend to have:

• more efficient metabolism;
• better body composition;
• more balanced stress regulation,” explains the specialist.

During physical activity, the body releases substances that communicate with the brain, liver and adipose tissue to help maintain metabolic balance.

“Exercise:

• improves insulin sensitivity and reduces circulating insulin levels;
• helps reduce chronically elevated cortisol, the stress hormone;
• promotes the release of endorphins and serotonin, with beneficial effects on mood and everyday stress.

It also increases SHBG, the protein that binds circulating sex hormones. This mechanism is relevant in both sexes, although with different implications: in women, it influences the proportion of free androgens, while in men it contributes to regulating the fraction of biologically active testosterone. It is an adaptive mechanism that plays a role from adolescence through older age,” says Dr Asteria.

Adolescence: the benefits and risks of sport for metabolic balance

Adolescence is a key period during which the hormonal axes involved in fertility, metabolism and body composition mature, alongside the achievement of peak bone mass. These processes are important in both girls and boys.

“Sport during adolescence is extremely valuable for building this bone mineral reserve. However, if there is a significant energy deficit at this stage, due to an overly restrictive diet or excessive training load, the body tends to conserve energy by suppressing reproductive function,” explains the endocrinologist.

In girls, this may lead to menstrual irregularities or even amenorrhoea; in boys, it may result in delayed pubertal development and impaired bone development.

This condition is known as Relative Energy Deficiency in Sport (RED-S). It is now recognised in both sexes and is characterised by inadequate energy availability, hormonal dysfunction and impaired bone health.

Sport should support growth rather than become an additional source of physiological stress. A healthy relationship with physical activity may also play an important preventive role in relation to eating disorders, which can affect both girls and boys.

Adulthood: physical activity as an ally against insulin resistance

In women, polycystic ovary syndrome (PCOS) is one of the clearest examples of how physical activity can influence hormonal regulation.

“The central issue is often insulin resistance: elevated insulin levels stimulate the ovaries to produce excess androgens, which can interfere with ovulation. International guidelines recommend physical activity as a first-line intervention. In this sense, it acts as a form of indirect hormonal therapy: by improving insulin sensitivity, it reduces the ovarian androgenic drive and supports a healthier body composition,” explains Dr Asteria.

A partly analogous mechanism can occur in men. Excess visceral fat and insulin resistance are among the most common contributors to lower testosterone levels in adulthood, with potential effects on energy levels, muscle mass and fertility.

Here too, physical activity, by improving insulin sensitivity and reducing abdominal fat, is one of the first interventions recommended.

Older age: physical activity to reduce the risk of sarcopenia

The key issue, explains the specialist, is not only that hormone levels change with age, but that both men and women become increasingly vulnerable to sarcopenia, the progressive loss of muscle mass, often accompanied by a decline in strength.

“Less muscle means a lower basal metabolic rate and a greater tendency to accumulate abdominal fat, particularly visceral fat, which is metabolically active, promotes inflammation and can worsen glucose and lipid metabolism. At this stage, the strategy cannot simply be to eat less, because this risks further reducing muscle mass. What is especially important is resistance training.”

In women, the decline in oestrogen levels during menopause can accentuate these mechanisms, worsening carbohydrate metabolism and appetite regulation. In men, a similar but more gradual process accompanies the physiological age-related decline in testosterone, with comparable effects on muscle mass and fat distribution.

In both cases, exercise works on 2 fronts:

• resistance training helps preserve and rebuild muscle mass;
• aerobic exercise and interval training improve cardiorespiratory fitness and insulin sensitivity, independently of changes in body weight.

“There is no single ‘magic’ activity. What matters is the right combination,” concludes Dr Asteria.

A balanced programme should include:

• resistance training, with progressively increasing loads 2 or 3 times per week, which also stimulates bone formation;
• aerobic exercise to support cardiovascular and metabolic health, such as brisk walking, stationary cycling, swimming or running, depending on joint health and individual fitness.

Yoga and Pilates can complement the programme by improving stability, flexibility and stress regulation.

The key principle is sustainability: consistency is more important than having a perfect training programme.

The benefits, in fact, go well beyond weight control. During menopause, women lose some of the vascular protection associated with oestrogen, and their cardiovascular risk tends to move closer to that of men, who are generally at higher risk throughout adulthood.

In both sexes, exercise helps control blood pressure, improves the lipid profile and increases cardiorespiratory fitness, a strong marker of long-term health. From a psychological perspective, it can also help reduce stress and anxiety and improve overall quality of life.

Some signs should not be ignored:

• unexplained changes in body weight;
• persistent fatigue;
• irregular menstrual cycles;
• reduced sexual desire or a decline in physical performance.

In these cases, or simply to establish an appropriate management plan in the presence of known metabolic conditions, an endocrinology and nutrition consultation can help clarify what is happening and define a personalised programme based on the individual’s medical history and goals.