Written by Robbie Clark, BExSc (Nutrition), M (Nutr+Diet), Accredited Practising Dietitian (APD) and Exercise Scientist · Last updated 28 October 2026 · 9 references
The short answer
- You can't target belly fat on its own. It comes off as you lose fat overall.
- Regular aerobic exercise reduces the deep fat around your organs, even without dieting.2
- Your metabolism doesn't crash at 40. Less muscle and less movement matter more than age.1
- Sleep counts. Short sleep means you lose more muscle and less fat on the same diet.3
- Measure your waist. Over 94 cm for men is linked with higher risk of heart disease and type 2 diabetes.5
How to lose belly fat is one of the questions men ask me most. It can feel like the last place fat ever leaves. Here's why it's stubborn, what the research says works, and when it's worth getting checked.
Why is belly fat so hard for men to lose?
Men tend to store more fat around the middle than women, including visceral fat, the deeper fat that sits around your organs. Visceral fat is the type most closely linked with heart disease and type 2 diabetes.
The frustrating part is that you can't choose where fat comes off. Sit-ups strengthen your abdominal muscles, but they don't burn the fat sitting over them. Belly fat shrinks as you lose fat across your whole body, which takes consistent changes over months rather than weeks.
The good news is that visceral fat responds well to exercise. A review of trials in overweight adults found that aerobic exercise reduced visceral fat even without a reduced-energy diet, with changes seen within 12 weeks. Moderate- to high-intensity aerobic training had the biggest effect.2
Does your metabolism slow down after 40?
Not as much as most people think. A study of more than 6,000 people found that daily energy use (adjusted for body size) stays fairly stable from about age 20 to 60, and only starts to fall after 60.1
What usually changes in your 40s and 50s is lifestyle. Many men lose muscle, move less, sleep less and drink a bit more. Muscle uses more energy than fat, so keeping it through resistance training helps you stay lean as you age.
Get support from a practitioner who helps with weight and metabolic health
Find practitioners on HealthBank who work with weight management, metabolic health and type 2 diabetes. Many offer a free discovery call, online, by phone or in person.
Find a men's health practitioner →How do you know if belly fat is a health risk?
Your waist measurement is a simple guide. The Heart Foundation says a waist of over 94 cm for men (over 80 cm for women) puts your health at risk.5 Measure halfway between your lowest rib and the top of your hip bone, after breathing out normally.
Waist size is less accurate for some groups, including Aboriginal and Torres Strait Islander peoples and South Asian, Chinese and Japanese adults, so talk to your practitioner about what's right for you.5
Do hormones cause belly fat in men?
Hormones play a part, but they're rarely the whole story. Insulin resistance, where your body's cells respond less well to insulin, is linked with carrying more fat around the middle and raises the risk of type 2 diabetes. Long-term stress and the stress hormone cortisol may also make it harder to manage appetite and weight.
Low testosterone and belly fat often go together, and the link runs both ways. Carrying extra fat can lower testosterone, and a review of studies found that losing weight raised testosterone in men with obesity, with bigger rises after bigger weight losses.4
If you have symptoms such as low energy, low mood, low sex drive or losing muscle, see your doctor for a blood test.6 Don't self-treat with testosterone or "testosterone booster" supplements.
Can poor sleep make belly fat worse?
Yes. In one trial, overweight adults followed the same reduced-energy diet with either 8.5 or 5.5 hours in bed each night. With less sleep, they lost about half as much fat, lost more muscle and felt hungrier.3 Most adults need 7–9 hours a night.7
Skip the crash diet
Very low-energy diets can work in the short term, but they're hard to stick to, leave you hungry and can cost you muscle. A steady rate of about ½ to 1 kg a week is easier to keep up and more likely to last.8
What's the best way to lose belly fat?
- Eat a little less than you use. A modest, steady energy deficit is the foundation of fat loss.8
- Build meals around protein, vegetables and wholegrains. Protein and fibre help keep you full on less energy.
- Do regular aerobic exercise. Moderate- to high-intensity cardio such as brisk walking, cycling or running reduces visceral fat.2
- Lift weights. Australian guidelines recommend muscle-strengthening activity on at least two days a week, which helps you keep muscle as you lose fat.9
- Protect your sleep. Aim for 7–9 hours with regular bed and wake times.7
- Watch the drinks. Alcohol adds energy quickly and often leads to extra snacking.
If the scales have stalled, see why weight loss stops and how to break a plateau.
Get support from a practitioner who helps with weight and metabolic health
Find practitioners on HealthBank who work with weight management, metabolic health and type 2 diabetes. Many offer a free discovery call, online, by phone or in person.
Find a weight management practitioner →Frequently asked questions
Can you lose belly fat with sit-ups?
No. Sit-ups strengthen your abdominal muscles, but belly fat only shrinks as you lose fat across your whole body.
What exercise is best for belly fat?
Regular moderate- to high-intensity aerobic exercise has the strongest evidence for reducing visceral fat, and resistance training helps you keep muscle.2,9
What waist size is healthy for men?
The Heart Foundation says a waist over 94 cm for men puts your health at risk.5
Does low testosterone cause belly fat?
They're linked both ways, and losing weight tends to raise testosterone. See your doctor if you have symptoms of low testosterone.4,6
Why is belly fat harder to lose after 40?
Mostly because of muscle loss and less activity, not a crashing metabolism. Energy use stays fairly stable until about 60.1
References
Research (PubMed)
- Pontzer H, Yamada Y, Sagayama H, et al. Daily energy expenditure through the human life course. Science. 2021;373(6556):808–812. PubMed 34385400
- Vissers D, Hens W, Taeymans J, Baeyens JP, Poortmans J, Van Gaal L. The effect of exercise on visceral adipose tissue in overweight adults: a systematic review and meta-analysis. PLoS One. 2013;8(2):e56415. PubMed 23409182
- Nedeltcheva AV, Kilkus JM, Imperial J, Schoeller DA, Penev PD. Insufficient sleep undermines dietary efforts to reduce adiposity. Ann Intern Med. 2010;153(7):435–441. PubMed 20921542
- Corona G, et al. Body weight loss reverts obesity-associated hypogonadotropic hypogonadism: a systematic review and meta-analysis. Eur J Endocrinol. 2013;168(6):829–843. PubMed 23482592
Australian guidelines
- Heart Foundation. Waist measurement. View source
- Healthy Male. Low testosterone (androgen deficiency). View source
- Sleep Health Foundation. How much sleep do you really need? View source
- Better Health Channel (Victorian Government). Weight loss – a healthy approach. View source
- Australian Government Department of Health. Physical activity and exercise guidelines for adults. View source
This article is general information, not medical advice. Speak with your practitioner about your own situation before changing your diet or activity.
Robbie is a Sydney-based Accredited Practising Dietitian (APD) and Exercise Scientist with over 17 years of experience. He holds a Bachelor of Exercise Science (Nutrition) and a Master of Nutrition and Dietetics, and is the Director and Co-founder of HealthBank.