Why Men Tend to Gain Belly Fat: Causes and Risks

Why men have a tendency to belly fat is a question rooted in biology, hormones and metabolism. Men are predisposed to store excess fat in the abdominal region, a pattern known as central or android adiposity, driven largely by sex hormones, age-related changes and lifestyle factors. Unlike subcutaneous fat, the visceral fat that accumulates deep within the abdomen is metabolically active and carries significant health risks. Understanding why this happens, and what can be done about it, is important for long-term cardiovascular and metabolic health.

Why do men store more fat around their belly than women?

Men store more abdominal fat because their hormonal environment, with relatively lower oestrogen, favours visceral rather than peripheral fat deposition. After the menopause, women's fat distribution shifts centrally as oestrogen falls, illustrating how strongly hormones govern fat storage.

Men are biologically predisposed to store excess fat in the abdominal region, a pattern known as android or central adiposity, whereas women tend to store fat around the hips, thighs and buttocks (a gynoid pattern). This difference is driven primarily by sex hormones, which influence where the body preferentially deposits adipose tissue. Both sexes produce oestrogen and testosterone, but in different proportions: oestrogen promotes peripheral fat storage, and the hormonal environment typical in men favours visceral fat accumulation around the internal organs of the abdomen.^[2][4] It is worth noting that after the menopause, women's oestrogen levels fall and their fat distribution often shifts towards a more central pattern, which helps illustrate how strongly hormones shape where fat is stored.^[4][6]

Visceral fat, which sits deep within the abdominal cavity surrounding organs such as the liver, pancreas and intestines, is metabolically distinct from subcutaneous fat (the fat just beneath the skin). It is more hormonally active and releases a greater quantity of inflammatory molecules and free fatty acids directly into the portal circulation, which can affect liver function and metabolic health.^[7]

Genetics also plays a role. Men with a family history of central obesity may be more likely to accumulate abdominal fat, though genetic predisposition interacts with lifestyle factors including diet, physical activity, alcohol consumption and sleep quality. Understanding this biological basis is important because it explains why two people of the same weight can carry very different health risks depending on where their fat is distributed.

If you are unsure whether your waist size is in a healthy range, the NHS recommends measuring at the midpoint between your lower rib and the top of your hip bone, after breathing out gently. Your GP can advise on what your measurement means for your individual health.

How do hormones like testosterone and cortisol affect belly fat?

Declining testosterone from around age 30 is associated with increased visceral fat and reduced insulin sensitivity, while chronically elevated cortisol directly stimulates preferential fat deposition in the abdomen. Insulin resistance, worsened by visceral fat, creates a self-reinforcing cycle of further fat accumulation.

Testosterone and cortisol both influence abdominal fat accumulation in men, though they act through different mechanisms. Testosterone generally has a protective association with visceral fat: higher levels are associated with greater lean muscle mass and lower central adiposity. However, as testosterone levels decline gradually from around the age of 30 onwards, the body tends to become more prone to storing fat in the abdominal area. Low testosterone is associated with increased visceral fat, reduced insulin sensitivity and a higher risk of metabolic syndrome, though these are associations rather than simple cause-and-effect relationships.^[4][12]

It is important to note that testosterone therapy is not a weight-loss treatment. It is only considered for men with confirmed hypogonadism, diagnosed through symptoms and blood tests (typically a morning total testosterone measurement), and managed according to clinical guidelines. If you experience persistent symptoms such as low libido, erectile dysfunction or consistently low energy in the mornings, speak to your GP, who can arrange appropriate assessment.

Cortisol, the body's primary stress hormone produced by the adrenal glands, has a more directly harmful relationship with belly fat. Chronic stress leads to sustained elevation of cortisol, which promotes the breakdown of muscle tissue, increases appetite (particularly for calorie-dense foods), and stimulates preferential deposition of fat in visceral depots. Cortisol receptors are particularly abundant in visceral adipose tissue, making this area especially responsive to stress-related hormonal signals.^[8][9]

Insulin is another key hormone in this picture. Visceral fat is associated with insulin resistance, a state in which cells respond less effectively to insulin, leading the pancreas to produce more of it. Elevated insulin levels further promote fat storage and make it harder to mobilise stored fat for energy. This creates a self-reinforcing cycle: visceral fat worsens insulin resistance, which in turn encourages further fat accumulation.

In rare cases, very high cortisol levels result from an underlying medical condition (hypercortisolism or Cushing's syndrome). Red flags that warrant GP assessment include easy bruising, wide purple stretch marks, or weakness in the muscles of the upper arms and thighs. Managing stress, maintaining adequate sleep and supporting healthy testosterone levels through lifestyle measures are all relevant strategies for most men.

Does age make it harder for men to lose abdominal fat?

Yes, age makes abdominal fat loss progressively harder due to declining testosterone, reduced growth hormone, muscle loss and poorer sleep quality, all of which lower metabolic rate and promote fat gain. UK guidelines recommend at least 150 minutes of moderate activity weekly plus resistance exercise on two or more days.

Age does make it progressively harder for men to lose abdominal fat, and this is due to a combination of hormonal, metabolic and lifestyle changes that accumulate over time. From the mid-thirties onwards, men experience a gradual decline in testosterone, a reduction in basal metabolic rate and a loss of skeletal muscle mass (sarcopenia). Because muscle tissue is metabolically active and burns more calories at rest than fat tissue, losing muscle means the body requires fewer calories to maintain its weight, making fat gain more likely even without changes in diet.

The decline in growth hormone secretion that accompanies ageing also contributes. Growth hormone supports fat metabolism and muscle maintenance, and its reduction over time shifts the body's composition towards greater fat mass and less lean tissue. These changes are compounded by the fact that many men become less physically active as they age, further reducing calorie expenditure and accelerating muscle loss.

Sleep quality tends to deteriorate with age for many men. Poor sleep is associated with elevated cortisol, increased levels of the appetite-stimulating hormone ghrelin, and reduced levels of leptin, which signals satiety.^[13][14] Together, these hormonal shifts can make overeating more likely and fat loss more difficult.

None of this means that losing abdominal fat becomes impossible with age, but it does mean that the strategies required may need to be more deliberate. The UK Chief Medical Officers' physical activity guidelines recommend at least 150 minutes of moderate-intensity activity per week, plus muscle-strengthening activity on two or more days per week.^[16][17] Resistance exercise is particularly valuable for preserving muscle mass, and adequate protein intake supports this. Stress management and good sleep hygiene are also relevant.

If you notice unexplained rapid weight gain around the abdomen, symptoms that might suggest an underactive thyroid (such as persistent fatigue, feeling cold or unexplained weight gain), or signs of obstructive sleep apnoea (loud snoring, witnessed pauses in breathing, or excessive daytime sleepiness), speak to your GP. These are situations where medical assessment is appropriate before assuming the cause is simply ageing or lifestyle.

What health risks does excess belly fat cause in men?

Excess belly fat in men significantly raises the risk of cardiovascular disease, type 2 diabetes, MASLD and obstructive sleep apnoea, driven by visceral fat's metabolic activity and systemic inflammation. NICE thresholds of 94 cm and 102 cm waist circumference indicate increased and high risk respectively.

Excess abdominal fat in men is associated with a significantly increased risk of several serious health conditions, making waist circumference a clinically important measurement alongside body mass index (BMI). NICE guidance recognises that a waist circumference above 94 cm in men indicates increased health risk, and above 102 cm indicates high risk, regardless of overall weight.^[19] Current UK guidance also recommends using waist-to-height ratio as a complementary measure: a ratio below 0.5 (that is, your waist circumference should be less than half your height) is the general target for lower risk. These thresholds reflect the particular danger of visceral fat, which is metabolically active and drives systemic inflammation.

It is important to note that some ethnic groups, including South Asian, Chinese, other Asian, Middle Eastern and Black populations, face higher health risks at lower waist sizes than the standard thresholds suggest.^[19] Your GP can advise on what measurements mean for your individual background and risk profile.

The health risks associated with central obesity in men include:

• Cardiovascular disease: Visceral fat promotes dyslipidaemia (raised triglycerides and low HDL cholesterol), hypertension and arterial inflammation, all of which increase the risk of heart attack and stroke.

• Type 2 diabetes: Visceral fat is strongly linked to insulin resistance, a key driver in the development of type 2 diabetes.

• Metabolic dysfunction-associated steatotic liver disease (MASLD, formerly known as NAFLD): Free fatty acids released by visceral fat travel directly to the liver via the portal vein, contributing to fat accumulation and inflammation in liver tissue.

• Obstructive sleep apnoea: Fat deposited around the neck and abdomen can obstruct the airway during sleep, disrupting breathing and worsening cardiovascular risk.

• Certain cancers: Central obesity is associated with an increased risk of colorectal, oesophageal and pancreatic cancers, among others, according to evidence reviewed by Cancer Research UK and the World Cancer Research Fund.

If you are concerned about your waist measurement or overall weight, your GP can assess your cardiovascular and metabolic risk. A typical assessment may include blood pressure measurement, HbA1c or fasting glucose, a lipid profile and a QRISK3 cardiovascular risk calculation. If obstructive sleep apnoea is suspected, your GP can refer you for further assessment.

For those considering structured weight management support, Bolt Pharmacy is a GPhC-registered UK online pharmacy offering online weight-management consultations, with prescriber review and pharmacist support, where treatment is only recommended when it is clinically appropriate. Addressing abdominal fat through sustainable lifestyle changes, and medical support where indicated, can meaningfully reduce these long-term health risks.

Scientific References

1. Differences in fat distribution between metabolically unhealthy lean and metabolically unhealthy obese individuals.
2. Sex-dependent Depot Differences in Adipose Tissue Development and Function; Role of Sex Steroids.
3. Role of antilipolytic mechanisms in adipose tissue distribution and function in man.
4. Metabolic benefits afforded by estradiol and testosterone in both sexes: clinical considerations.
5. Association of Adiposity Phenotypes With 27-Hydroxycholesterol and Sex Hormones: The Multiethnic Cohort Study.
6. Female Adipose Tissue Sex Steroid Biosynthesis.
7. Visceral fat and metabolic inflammation: the portal theory revisited.
8. Deconstructing the roles of glucocorticoids in adipose tissue biology and the development of central obesity.
9. The role of mediastinal adipose tissue 11β-hydroxysteroid dehydrogenase type 1 and glucocorticoid expression in the development of coronary atherosclerosis in obese patients with ischemic heart disease.
10. Glucocorticoid receptors in human epicardial adipose tissue: role of coronary status.
11. Cushing's syndrome.
12. Metabolic syndrome.
13. Effects of acute sleep loss on leptin, ghrelin, and adiponectin.
14. Sleep loss as a cardiometabolic risk factor: a narrative review of clinical and public health implications.
15. Metabolic consequences of sleep and sleep loss.
16. Physical activity guidelines: UK Chief Medical Officers' report.
17. UK Chief Medical Officers' physical activity guidelines (full guidance).
18. Physical activity guidelines for adults aged 19 to 64.
19. Overweight and obesity management (NG246): Identifying and assessing overweight, obesity and central adiposity.
20. Calculate your waist to height ratio.
21. Keep the size of your waist to less than half of your height – NICE recommends.
22. Waist-to-height ratio as a measure of abdominal obesity in southern Chinese and European children and adolescents.
23. SIRT1 transcription is decreased in visceral adipose tissue of morbidly obese patients with severe hepatic steatosis.

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