How to lose belly fat: what works, what doesn't, and the waist size that matters

Two kinds of belly fat

Fat under your skin is the kind you can pinch. Visceral fat sits around your organs, and on scans it predicts heart disease, type 2 diabetes and early death, whatever you weigh.

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Crunches don't burn it

Six weeks of ab exercises on 5 days a week didn't change belly fat in 24 adults, adding ab training to a diet did no better than the diet alone, and across 13 studies training one body part didn't take the fat off it.

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Move more: aerobic exercise has the best evidence

Across 25 trials, aerobic exercise took about 3 cm off the waist on average, and each extra 30 minutes a week took off about 0.56 cm more, in trials lasting 8 weeks or longer.

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Eat a little less

Eating less cuts visceral fat too, and takes off more weight; exercise cuts visceral fat even when the scales barely move. Doing both works best.

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Sleep and alcohol

Adults need 7 to 9 hours' sleep, and short sleep with free access to food added belly fat in a small trial. Alcohol is high in calories, and regularly drinking more than 14 units a week can show on your waistline.

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Your waist matters more than your weight

Keep your waist to less than half your height, measured midway between your lowest rib and the top of your hip bone. That's a measure of health, not of how you look.

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Fat under the skin

Subcutaneous fat sits between your skin and your muscles: it's the fat you can pinch, and in most people there's more of it than visceral fat.

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Visceral fat

Visceral fat surrounds the organs inside your abdomen, and a third kind, ectopic fat, collects in organs such as the liver and heart. Measured on CT (computed tomography) or MRI (magnetic resonance imaging) scans, visceral fat predicts heart and metabolic disease and early death independently of your weight, and fat in the liver and heart may add to the risk.

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Why the waist matters

An international consensus calls waist size a vital sign: it predicts disease beyond body mass index (BMI), and shrinking it is worth doing in its own right. Exercise and eating less shrink the waist with or without weight loss, and changes in waist size track changes in visceral fat.

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What comes off first

Across 89 studies, visceral fat fell by a bigger share than fat under the skin with every method tested, from diet and exercise to medicines and surgery, but none of them targeted it. Modest weight loss trimmed visceral fat proportionally the most.

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Where people differ

Genes play a part: identical twins overfed by the same amount gained visceral fat in similar amounts. NICE says people from South Asian, Chinese, other Asian, Middle Eastern, Black African or African-Caribbean backgrounds are prone to central fat and face health risks at a lower BMI. Around the menopause, fat gain speeds up and visceral fat rises.

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Less than half your height

NICE uses the waist-to-height ratio alongside BMI for adults with a BMI under 35, with the same bands for women and men of every background: 0.4 to 0.49 is healthy, 0.5 to 0.59 means increased health risks, and 0.6 or more means further increased health risks. In plain words: keep your waist to less than half your height.

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A worked example

A waist of 96.5 cm and a height of 170 cm give a ratio of 0.57 (96.5 divided by 170): increased health risks. Use the same units for both. Our waist-to-height ratio calculator does the sum.

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Waist size alone

As our waist calculators explain, the International Diabetes Federation (IDF) uses 94 cm for Europid men and 80 cm for women, and 90 cm for South Asian, Chinese and Japanese men. NICE and the NHS now use the waist-to-height ratio instead, which has one cut-off for everyone.

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BMI

For most adults a BMI of 25 to 29.9 is overweight and 30 or more is obese; for people from South Asian, Chinese, other Asian, Middle Eastern, Black African or African-Caribbean backgrounds the cut-offs are 23 and 27.5. BMI can't tell muscle from fat, which is why the waist is measured too.

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Bathroom scales and "visceral fat" readings

They weigh you accurately but estimate body fat poorly: three smart scales were 2.2 to 4.4 kg of fat out against a scan, and 15 devices read from 3.5 points too low to 11.7 points too high. NICE says not to use them instead of BMI, and we found no study checking their visceral fat readings. Use a tape measure.

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Health, not looks

These numbers are about your risk of type 2 diabetes, heart disease and other conditions, not about how your stomach looks. The NHS says losing just 5 to 10% of your body weight can improve your health.

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Spot reduction doesn't workStrong evidence

In 24 inactive adults, 6 weeks of ab exercises on 5 days a week, with diet held steady, changed neither belly fat nor waist size. In 40 women with overweight or obesity, adding 12 weeks of ab training to a diet took off no more belly fat than the diet alone. Across 13 studies of 1,158 people, training one body part didn't reduce the fat over it; in 104 adults who trained one arm, fat loss on MRI spread across both arms, and in 11 adults who trained one leg for 12 weeks, the fat came off the arms and trunk rather than that leg.

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The small trials that disagreeMixed evidence

In 16 men, adding 57 minutes of machine crunches and twists to running, 4 days a week for 10 weeks, took about 0.7 kg more fat off the trunk than running alone, with the same total fat loss; the scan couldn't tell visceral fat from fat under the skin. A small circuit trial thinned the fat over the upper belly but not over the trained arm. Neither is a practical plan, and neither has been repeated.

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Exercise cuts visceral fat even without weight lossStrong evidence

In 117 studies, when weight didn't change, exercise cut visceral fat by about 6.1% against about 1.1% for diet. In 15 studies, aerobic exercise without dieting cut visceral fat on CT scans by more than 30 cm2 in women and 40 cm2 in men within 12 weeks.

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More minutes, more off the waistStrong evidence

In 116 trials of 6,880 adults with overweight or obesity, each extra 30 minutes a week of supervised aerobic exercise took off about 0.52 kg, 0.56 cm of waist and 1.6 cm2 of visceral fat area, fairly evenly up to 300 minutes a week; more than 150 minutes a week at moderate intensity or above was needed for a change that matters for health. In 25 trials, the waist shrank by 3.2 cm on average: 4.2 cm with vigorous exercise and 2.5 cm with moderate.

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Eating less works tooStrong evidence

In 40 trials, eating less cut visceral fat more than exercise did (an effect size of 0.53, against 0.28), with moderate certainty, and diet took off more weight in 117 studies. Exercise's effect grew with the energy it used, and calorie for calorie it cut visceral fat more than dieting.

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Strength training: good for muscle, weaker for visceral fatMixed evidence

On its own, strength training trimmed body fat by about 1.5 percentage points across 58 studies, with a small effect on visceral fat in healthy adults. But in 35 trials it didn't significantly reduce visceral fat; in 84 trials it helped men and people under 40% body fat, but not women or people at 40% or more; and in an 8-month trial, aerobic training cut visceral and liver fat while strength training cut only the fat under the skin of the belly.

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Strength training still earns its placeStrong evidence

In 119 adults with overweight training for 8 months, aerobic and combined training took off more weight and fat, while strength and combined training added more lean mass. Doing both, as the guidelines ask, keeps your muscle while you lose fat.

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Intervals work, but aren't magicEmerging evidence

In 39 studies, high-intensity interval training (HIIT) reduced total, belly and visceral fat, with running doing more than cycling. But when the energy used was matched, harder exercise didn't add extra waist loss in the trials an international consensus reviewed.

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Short sleep and belly fatEmerging evidence

In one inpatient trial, 12 healthy adults allowed only 4 hours in bed for 2 weeks, with free access to food, ate about 308 calories a day more and gained belly fat (about 9%, and about 11% for visceral fat) compared with 9-hour nights. In a 5-year study of 1,107 adults, sleeping 5 hours or less went with more belly fat gain, but only in people under 40. Small, short evidence, but it fits the advice to sleep 7 to 9 hours.

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Alcohol and the "beer belly"Emerging evidence

A pint of 5% beer has up to 222 calories and a glass of wine up to 158. In 20,625 adults, beer went with a bigger waist in men, mostly through weight gain everywhere rather than at the belly alone. A review found that drinking more than about 500 mL of beer a day may be linked with belly fat, but the evidence is low quality.

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Stress and cortisolMixed evidence

In a lab study of 59 women, those with more central fat produced more cortisol, a stress hormone, under stress, but that kind of study can't show which came first, and no trial we found shows that lowering stress alone shrinks belly fat. A real excess of cortisol, Cushing's syndrome, is a rare medical condition.

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Around the menopauseEmerging evidence

Fat gain about doubled from the start of the menopause transition until about 2 years after the last period, while lean mass fell, in a large US cohort; in 156 women, visceral fat rose only in those who became postmenopausal, not just with age. Exercise still works: in 101 trials in postmenopausal women it reduced fat mass, waist size and visceral fat.

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The benefit lastsEmerging evidence

In two 18-month diet and activity trials followed up 5 to 10 years later, waist size and belly fat stayed partly lower even in people who had regained all their weight, and each 10% of visceral fat lost went with a 28% lower risk of type 2 diabetes.

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Build up your activity

The guidelines ask for at least 150 minutes a week of moderate activity, such as brisk walking, or 75 of vigorous activity, plus strength work on 2 days. For your waist, more is better, up to about 300 minutes a week. Our weight-loss plan builds from about 90 minutes a week.

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Pick aerobic exercise you'll keep doing

Walking, cycling, swimming, running and rowing all count. Intervals save time and work, but they haven't reliably beaten steady exercise when the energy used was matched. If you live with obesity or a heart condition, our weight-loss plan explains the checks to have before hard intervals.

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Keep strength training on 2 days

It keeps your muscle while you lose fat. Work all your major muscles, as the guidelines ask, using our full-body workouts and plans.

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Eat a little less

The NHS suggests aiming to lose 0.5 to 1 kg (1 to 2 lb) a week by eating and drinking fewer calories than you use, being active for 45 to 60 minutes a day, and cutting down on alcohol. Our calories per day calculator turns that into a daily figure, about 600 calories below your needs and never below 1,200.

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Sleep 7 to 9 hours

That's what adults need, as the NHS says. Short sleep raised how much people ate in a small trial; our sleep guide covers how exercise helps.

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Keep alcohol within 14 units a week

Spread over 3 or more days, as the NHS advises. Alcohol has 7 calories in every gram, and regular drinking above that can show on your waistline.

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Measure your waist, not just your weight

Your waist and visceral fat can shrink even when your weight doesn't change, so the tape tells you more than the scales.

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Around the menopause

The same approach works: aerobic and combined training did most for fat, and strength and combined training did most for muscle, in 101 trials. Our menopause guide has the detail.

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Type 2 diabetes, prediabetes, fatty liver or PCOS

The same evidence applies, with each condition's own cautions; our guides to each cover them. With insulin or some other diabetes medicines, more exercise can bring on low blood sugar, as our type 2 diabetes guide explains.

Some ethnic backgrounds

NICE uses lower BMI cut-offs for people from South Asian, Chinese, other Asian, Middle Eastern, Black African or African-Caribbean backgrounds, because central fat raises their risk at a lower BMI. The waist-to-height ratio is the same for everyone.

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After a birth or a caesarean

The NHS advises avoiding sit-ups, planks and high-impact exercise to start with and building up from gentle tummy and pelvic floor exercises. Walking is a good start; our postpartum guide covers timing.

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Living with a higher weight

Body weight alone isn't a reason for a medical check before you start walking or lifting; chest pain, breathlessness or dizziness when you're active, or known heart, kidney or metabolic disease, are, as our weight-loss plan explains. Low-impact options count just as much.

A few centimetres over months

In trials lasting 8 weeks or more, aerobic exercise took a few centimetres off the waist (about 3 cm on average), more with more minutes and with eating less. The NHS aims for 0.5 to 1 kg of weight a week when you're eating less. Nobody can promise how fast your belly in particular will shrink.

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Your waist can move before the scales

Exercise trimmed the waist and visceral fat even without weight loss, so measure your waist every 2 to 4 weeks rather than judging by your weight alone.

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It pays to keep going

Visceral fat lost in lifestyle trials stayed partly lower 5 to 10 years later, with a lower risk of type 2 diabetes.

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Call 999 (911 in the US)

If you have bloating with a swollen stomach and a stomach ache that is severe and came on very suddenly, you're vomiting blood or your vomit looks like ground coffee, or you have severe difficulty breathing. Don't drive yourself to A&E. During exercise, stop and get help for chest pain or pressure, unusual breathlessness, dizziness or fainting, as our plans advise.

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Ask for an urgent GP appointment or call NHS 111

If you have bloating with being sick, diarrhoea or constipation, or with a stomach ache; a high temperature, or you feel hot, cold or shivery; a swelling or lump in your tummy; or you can't pee, poo or fart. In the US, contact your doctor or urgent care.

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See a GP

If you feel bloated regularly, or have bloating with weight loss you can't explain or blood in your poo: the NHS says bloating that doesn't go away can sometimes be a sign of something more serious, such as ovarian cancer, whose symptoms include a swollen tummy or feeling bloated roughly 12 or more times a month. If you're losing weight without trying: it "can be a sign of stress or a serious illness. See a GP just in case." And if fat is building up on your tummy, neck and upper back while your arms and legs look thin, with a red, round face or stretch marks, especially on long-term steroid medicines: this can be Cushing's syndrome.

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Help to lose weight

The NHS suggests seeing a GP if your BMI is in the overweight or obese range and you want help to lose weight, your waist is more than half your height, or you have conditions such as diabetes, high blood pressure or sleep apnoea.

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Hips and legs that don't follow

If your bottom, thighs and lower legs (sometimes your arms) are out of proportion with the rest of your body, feel painful, tender or heavy, and bruise easily, ask your GP about lipoedema, as our weight-loss guide explains.

When eating or exercise becomes harmful

The NHS lists spending a lot of time worrying about your weight and body shape, eating very little food, exercising too much, and having very strict habits or routines around food among the signs of an eating disorder, and says to see a GP as soon as you can. Beat adds exercising to make up for eating, in secret or when ill or injured. Beat's helpline in England is 0808 801 0677, and our eating disorders guide has the other numbers.

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"You can spot-reduce belly fat"Strong evidence

Crunches, twists and ab gadgets didn't shrink belly fat in trials, and training one body part didn't take the fat off it across 13 studies. Fat comes off your whole body.

Sources 3, 4, 5

"Belly fat only comes off with diet"Strong evidence

Both work: diet takes off more weight, and exercise cuts visceral fat even without weight loss, more so the more you do.

Sources 8, 9

"Strength training is best for belly fat"Mixed evidence

It trims body fat a little and keeps your muscle, but aerobic exercise has more consistent effects on visceral fat. Do both.

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"HIIT is the only way to burn belly fat"Mixed evidence

Intervals work, but steady exercise works too, and when the energy used was matched, intensity didn't add extra waist loss.

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"Some foods, drinks or supplements melt belly fat"Emerging evidence

Across 89 studies, no diet, exercise, medicine or surgery targeted visceral fat; it fell along with fat everywhere else.

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"Cortisol causes your belly fat"Mixed evidence

Cortisol and central fat went together in a small lab study, but no trial shows that lowering stress alone shrinks belly fat. A real cortisol excess, Cushing's syndrome, is rare and needs a GP.

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"If the scales don't move, it isn't working"Strong evidence

Exercise shrank the waist and visceral fat with or without weight loss. Measure your waist.

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"A flat stomach means you're healthy"Strong evidence

Visceral fat can't be seen or pinched, and NICE says BMI isn't a direct measure of central fat. Your waist-to-height ratio says more about your health than how your stomach looks.

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