Male vs Female Metabolism: Why the Difference Matters

For many years, nutrition and exercise advice has often been delivered as though the same approach should work equally well for men and women. The basic principles of good health are similar, but male and female physiology is not identical. Differences in hormones, body composition, muscle mass, fat distribution, bone health and the way the body uses fuel can all influence metabolic health, exercise performance and the response to weight loss.

This becomes more important as we age. For women, the transition through perimenopause and menopause can bring significant changes in body composition and metabolism. For men, increasing visceral fat and declining muscle mass with age can substantially increase cardiometabolic risk. The goal should therefore not simply be to eat less and exercise more. A better approach is to consider the individual’s sex, age, body composition, hormonal stage, metabolic health and physical activity.

Metabolic health is much broader than the number on the scales. It reflects how effectively the body regulates blood glucose, insulin, blood lipids, blood pressure and energy metabolism. It is also influenced by how much skeletal muscle we carry and where body fat is stored. Two people can have the same BMI and very different health profiles. One may have relatively high muscle mass and low levels of visceral fat, while another may have less muscle and more fat stored around the abdominal organs. Their body weight may look similar, but their metabolic risk can be very different. This is why I prefer to look at body composition, waist circumference, strength, fitness and metabolic markers alongside weight. The aim should be to reduce excess body fat where appropriate while protecting muscle, bone and physical function.

One of the clearest physiological differences between men and women is fat distribution. Men tend to accumulate more visceral fat around the abdominal organs. This type of fat is strongly associated with insulin resistance, type 2 diabetes, fatty liver disease and cardiovascular disease. Premenopausal women generally store a greater proportion of fat subcutaneously around the hips and thighs. This pattern tends to carry less cardiometabolic risk than visceral fat. Research has consistently demonstrated sex differences in adipose tissue metabolism, insulin sensitivity and fat storage. For women, this pattern can begin to change through menopause. As oestrogen declines, there is often a greater tendency for fat to accumulate centrally around the abdomen. At the same time, age related muscle loss is also occurring. This combination can make metabolic health more difficult to maintain, even when overall body weight has not changed dramatically.

Menopause is not only a reproductive transition. It also affects body composition, insulin sensitivity, bone health and fat distribution. Women may notice that the strategies they used successfully in their thirties no longer produce the same result in their forties and fifties. This does not mean the answer is simply more restriction. In fact, aggressive dieting can make matters worse if it leads to further muscle loss. During midlife, the emphasis should increasingly move towards preserving muscle, maintaining strength, supporting bone health and improving insulin sensitivity. Resistance training, adequate protein, cardiovascular fitness, good sleep and an appropriate overall energy intake all become more important at this stage. The goal is not simply a lower number on the scales. The goal is a healthier body composition and better metabolic function.

Skeletal muscle is often discussed in relation to strength and appearance, but it is also a major metabolic organ. Muscle plays an important role in glucose disposal and insulin sensitivity. When we eat carbohydrate and blood glucose rises, skeletal muscle is one of the main tissues responsible for taking glucose out of the bloodstream and either using or storing it. This is one of the reasons resistance training is so important for long term health. Maintaining muscle can support glucose regulation, metabolic flexibility and physical function. It also becomes increasingly important with age because both men and women progressively lose muscle if it is not actively maintained. Men generally begin adulthood with more muscle mass than women, partly because of higher testosterone levels. Women start with less total muscle mass, which makes protecting that muscle particularly important through midlife and beyond. For both sexes, weight loss that includes excessive muscle loss is not an ideal outcome.

There are also measurable differences in the way men and women use fuel during exercise. Research suggests that women tend to rely proportionally more on fat oxidation during moderate intensity aerobic exercise, while men tend to rely more heavily on carbohydrate at the same relative intensity. Hormones, particularly oestrogen, appear to contribute to some of these differences. However, exercise intensity, training status, nutrition, body composition and overall metabolic health also play a major role. This does not mean women should automatically follow a high fat diet or that men need more carbohydrate. It simply shows that male and female metabolism is not identical and that exercise and nutrition recommendations should not assume one physiological model fits everyone.

Insulin sensitivity is one of the most important components of metabolic health. When the body becomes less responsive to insulin, the pancreas has to produce more of it to control blood glucose. Over time, insulin resistance can contribute to type 2 diabetes, abdominal fat accumulation and cardiovascular disease. Visceral fat, inactivity and low muscle mass can all contribute to poorer insulin sensitivity. Exercise has the opposite effect. Muscle contraction increases glucose uptake, and regular training improves the ability of muscle to respond to insulin. This is another reason I believe resistance training should be considered a core health intervention, not an optional extra. It supports muscle, glucose regulation and long term physical function.

Protein becomes increasingly important as we age. Older muscle is less responsive to very small amounts of protein, which means both total intake and distribution across the day become more relevant. For many adults, it is useful to include a meaningful source of protein at each main meal rather than consuming most of the day’s protein at dinner. Depending on body size, activity level and health goals, around 25 to 35 grams of quality protein at a main meal may be appropriate for many people. Protein alone is not enough. Resistance exercise provides the stimulus for muscle to adapt, while protein provides the amino acids required for repair and maintenance. The combination is particularly important during weight loss, when the aim should be to reduce fat while preserving lean tissue.

For women, bone health becomes increasingly important through and after menopause. Declining oestrogen accelerates bone turnover and increases the risk of osteoporosis. This is why exercise for women in midlife should include more than walking or cardiovascular exercise alone. Resistance training and appropriate weight bearing exercise provide mechanical loading that supports both muscle and bone. Nutrition also matters. Adequate protein, calcium, vitamin D and overall dietary quality are important. Severe energy restriction is not a strategy I support in this group because losing weight at the expense of muscle and bone is not a healthy outcome.

Strength training has received more attention in recent years, but cardiovascular exercise remains essential. Aerobic exercise supports heart health, cardiorespiratory fitness, mitochondrial function and insulin sensitivity. The best approach for most people is not to choose between cardio and weights. Both are important. Resistance training supports muscle, strength and bone, while cardiovascular exercise supports fitness and metabolic health. Daily movement outside structured exercise also matters because sitting for long periods can offset some of the benefits of formal exercise.

Men and women share the same broad foundations of good health. A predominantly whole food diet, adequate protein, plenty of vegetables and fibre, regular resistance exercise, cardiovascular fitness, good sleep and maintaining a healthy body composition remain important for both sexes. The emphasis may differ. For men, reducing visceral fat and preserving muscle is often a major priority. For women, particularly through perimenopause and menopause, protecting muscle and bone while managing changes in fat distribution becomes increasingly important. There is also substantial variation between individuals. Age, genetics, medication, sleep, training history, existing metabolic health and body composition all influence outcomes. Sex is important, but it is one part of the bigger clinical picture.

The traditional message to simply eat less and exercise more does not adequately address metabolic health. Energy balance is important, but the quality of the weight being lost is just as relevant. Reducing body fat while preserving skeletal muscle produces a very different health outcome from losing the same amount of weight through a combination of fat and muscle loss. Fat distribution, age, hormonal stage, insulin sensitivity, cardiovascular fitness and overall diet quality all influence how the body responds to nutrition and exercise. This is why I prefer to focus on improving metabolic health and body composition rather than concentrating on weight alone.

As our population ages, I believe we need to shift the conversation away from simply being lighter. The goal should be to maintain muscle, minimise excess visceral fat, protect bone, preserve cardiovascular fitness and remain physically independent for as long as possible. Men and women do not need completely different health programs, but they do have different physiology. Recognising those differences allows us to make better decisions about nutrition, exercise and weight management without turning them into rigid rules. Ultimately, the best approach is individual. It should take into account sex, age, hormonal stage, body composition, metabolic health, physical activity and personal goals. That is a far more useful way to think about healthy ageing than focusing only on the number on the scales.

• Muscle is central to metabolic health for both men and women.

• Men tend to carry more visceral fat, while women experience important changes in fat distribution and bone health through menopause.

• Resistance training, adequate protein and cardiovascular fitness should be considered together.

• The focus should be on body composition and metabolic health, not weight alone.

Tramunt B, Smati S, Grandgeorge N, Lenfant F, Arnal JF, Montagner A, Gourdy P. Sex differences in metabolic regulation and diabetes susceptibility. Diabetologia. 2020;63:453 to 461.

Mauvais Jarvis F, Arnold AP, Reue K. A guide for the design of pre clinical studies on sex differences in metabolism. Cell Metabolism. 2017;25(6):1216 to 1230.

Chenevière X, Borrani F, Ebenegger V, Gojanovic B, Malatesta D. Effect of sex and menopausal status on substrate oxidation during exercise. European Journal of Sport Science. 2021.

Henderson GC. Sex differences in energy metabolism. Current Opinion in Clinical Nutrition and Metabolic Care. 2024.

Costa DN, Santosa S, Jensen MD. Sex differences in the metabolism of glucose and fatty acids by adipose tissue and skeletal muscle in humans. Physiological Reviews. 2025;105(3):897 to 934.

Silva RB, et al. Resistance training in postmenopausal women: effects on body composition, strength and physical function. Menopause. 2023.

Fausto DY, et al. The effect of physical exercise on bone health in menopausal women: an umbrella systematic review. Climacteric. 2023;26(6):550 to 559.

World Health Organization. WHO Guidelines on Physical Activity and Sedentary Behaviour. Geneva: World Health Organization; 2020.