Body Mass Index (BMI): How to Calculate It, the Healthy Range for Women and Men by Age, a Weight-for-Height Chart and When BMI Gets It Wrong

Body mass index (BMI) is your weight in kilograms divided by your height in meters squared. It tells you whether your weight fits your height. The healthy range for adult women and men is the same: 18.5 to 24.9. For example, at 5′7″ (170 cm) and 154 lb (70 kg), you get 70 ÷ (1.7 × 1.7) = 24.2. That's still healthy, right at the top of the range. Below you'll find a step-by-step calculation in metric and in pounds and inches, a weight and waist chart for heights from 4′11″ to 6′5″ (150–195 cm), the ranges for women and men, what changes after 40 and after 65, and when you shouldn't trust the number without a tape measure.

What body mass index is and what it shows

Body mass index shows how much you weigh relative to your height. It doesn't know what that weight is made of: muscle, fat, water or bone.

The formula was described by the Belgian mathematician and statistician Adolphe Quetelet in 1832, as the medical historian Garabed Eknoyan explains in a 2008 review. Quetelet studied how people grow and noticed that in adults, weight rises roughly in proportion to the square of height. For almost a century and a half the ratio was called the Quetelet index. The name "body mass index" came from the American physiologist Ancel Keys in 1972. Keys compared several ways of dividing weight by height in 7,424 healthy men from 12 groups in five countries. Weight divided by height squared came out slightly better than weight divided by height: it depended less on height itself and was more closely linked to the thickness of fat under the skin. Keys also chose it because it's easy to calculate and works for any population without tables of "average weight."

Why height is squared. If you divided weight by height alone, tall people would almost always get a bigger number, even with the same build. Squaring the height nearly removes that effect. That's why someone who is 5′1″ (155 cm) and someone who is 6′3″ (190 cm) can use the same chart.

What it's used for. The World Health Organization (WHO), in a fact sheet updated in December 2025, calls BMI a surrogate marker of fatness. That means the index stands in for a direct fat measurement where measuring fat would be slow and expensive. By this measure, 2.5 billion adults were overweight in 2022, which is 43% of adults on the planet, and 890 million, or 16%, were living with obesity. For counts like this BMI is ideal: all you need is a scale and a way to measure height.

What BMI doesn't show. The index can't see how much muscle you have or where your fat sits. Two people with a BMI of 27 can look completely different: one has muscle from several years in the gym, the other has fat around the stomach. That's why a doctor treats BMI as the first step and then looks at waist size, blood pressure and blood tests.

How to calculate BMI: the formula and examples

To calculate body mass index, divide your weight in kilograms by your height in meters multiplied by itself.

BMI = weight (kg) ÷ (height (m) × height (m))

Step by step for a height of 170 cm and a weight of 70 kg:

1. Convert height to meters: 170 cm = 1.70 m.
2. Multiply the height by itself: 1.70 × 1.70 = 2.89.
3. Divide your weight by that number: 70 ÷ 2.89 = 24.2.

That's your BMI. Rounding to one decimal place is enough.

If you use pounds and inches. Multiply your weight in pounds by 703 and divide by your height in inches squared. The 703 simply converts pounds and inches into kilograms and meters.

BMI = weight (lb) × 703 ÷ (height (in) × height (in))

For the same person, 154 lb and 5′7″ (67 inches): 154 × 703 = 108,262; 67 × 67 = 4,489; 108,262 ÷ 4,489 ≈ 24.1. The tiny difference from 24.2 comes from rounding pounds and inches.

A few more examples, all checked:

• 5′9″ (175 cm), 154 lb (70 kg): 1.75 × 1.75 = 3.0625; 70 ÷ 3.0625 ≈ 22.9. The middle of the healthy range.
• A woman, 5′5″ (165 cm), 165 lb (75 kg): 1.65 × 1.65 = 2.7225; 75 ÷ 2.7225 ≈ 27.5. Overweight.
• A man, about 6′0″ (182 cm), 198 lb (90 kg): 1.82 × 1.82 = 3.3124; 90 ÷ 3.3124 ≈ 27.2. Overweight.
• A man who has lifted weights for years, 5′11″ (180 cm), 209 lb (95 kg): 1.8 × 1.8 = 3.24; 95 ÷ 3.24 ≈ 29.3. By the chart, that's almost obesity. But his waist is 33 inches (84 cm), and 84 ÷ 180 = 0.47, which is less than half his height. His weight comes from muscle. There's more on this in section 08.

How to weigh yourself and measure your height so the number doesn't jump around. Your weight changes during the day because of food, water and salt, so weigh yourself in the morning, after using the bathroom, before breakfast and in minimal clothing. Compare the average over several days, since a single weigh-in tells you little. Measure your height without shoes, with your back against a wall: heels, buttocks and shoulder blades touch the wall, and someone places a book on top of your head at a right angle to the wall. People usually get shorter with age, so a BMI based on the height in an old medical record will come out too low.

You don't have to do the math by hand. In our calorie and BMI calculator, you just enter your height and weight, and it also works out how many calories you need a day.

Healthy BMI range by WHO: the chart

The healthy BMI range for adults is 18.5 to 24.9. Below 18.5 is underweight, 25 to 29.9 is overweight, and 30 and above is obesity, which is split into three classes. This scale is used by the WHO and by Russia's 2024 national clinical guidelines on obesity, published by Dedov, Mokrysheva, Melnichenko and colleagues.

In the last column we added the risk of dying from any cause, based on the largest analysis on the subject: the Global BMI Mortality Collaboration study published in The Lancet in 2016. The authors pooled 239 studies from four continents and selected 3,951,455 people who had never smoked and had no chronic disease. The typical follow-up was 13.7 years, and the reference point was a BMI of 22.5 to 25.

How to read this chart. Death rates were lowest at a BMI of 20 to 25. Mild overweight, from 25 to 27.4, added only 7% to the risk. That's a reason to take a closer look at your waist and habits, and too early to panic. Beyond that, risk climbs faster: with class I obesity it's almost one and a half times higher, with class II almost double, and with class III almost triple. Being underweight is risky too: at a BMI of 15 to 18.4, the risk was one and a half times higher than in the middle of the healthy range.

For every 5 BMI units above 25, risk rose by 39% in Europe, 29% in North America and also 39% in East Asia. The pattern repeats across continents. For you personally these numbers show the direction, and your actual risk also depends on blood pressure, blood sugar and cholesterol, waist size, smoking and how much you move.

Healthy weight for your height: a BMI chart with waist size

Find your height in the chart: the second column shows the weight that keeps your BMI in the healthy range, and the fifth shows what your waist should be. We calculated this chart ourselves from the BMI formulas. The waist limit is half your height, based on reviews by Browning in 2010 and Ashwell in 2012. The lower limit after 65 is a BMI of 23, based on the 2014 meta-analysis by Winter. Weights are rounded to whole numbers inside each range. Pounds and inches are in parentheses, calculated from the same formulas, with heights rounded to the nearest inch.

How to read the chart, with an example. A woman who is 5′5″ (165 cm) weighs 165 lb (75 kg). The healthy range for her height is 112 to 150 lb (51–68 kg), overweight starts at 151 lb (69 kg), and obesity at 181 lb (82 kg). So she's overweight, with a BMI of 27.5. At her height one BMI unit is 6 lb (2.7 kg), and she'd need to lose about 15 lb (7 kg) to reach the top of the healthy range. But first she should measure her waist: at 5′5″ it should be under 32.5 inches (82.5 cm), and the threshold for women in Russia's guidelines is 31.5 inches (80 cm). If her waist is within these limits, the extra weight isn't sitting on her stomach, and there's no rush to lose it.

How much that is in pounds. The "1 BMI unit" column turns the index into pounds and kilograms. At 5′7″ (170 cm), one unit is 6.4 lb (2.9 kg), so to go from a BMI of 27 down to 25 you'd need to lose about 13 lb (5.8 kg). At 5′11″ (180 cm), the same two units are already 14 lb (6.5 kg). That also answers a common question, "how many pounds is a BMI of 25": at 5′5″ (165 cm) a BMI of exactly 25 means 150 lb (68.1 kg), and at 5′9″ (175 cm) it means 169 lb (76.6 kg).

The "after 65" column is the weight below which the risk of death rises in older people. There's more on this in section 06. If a 70-year-old woman who is 5′3″ (160 cm) weighs 123 lb (56 kg), she's healthy by the adult scale, but by the data on older adults her weight is already in the zone worth keeping an eye on.

Healthy BMI for women and men: what's the same and what's different

The formula and cut-offs are the same for women and men: the healthy range is 18.5–24.9 for both sexes. What differs is what sits behind the number: at the same BMI, a woman on average carries more fat.

How much fat sits behind the same number. In a 2002 study by Jackson and colleagues, 665 people aged 17 to 65 who didn't play sports were weighed underwater, one of the accurate ways to find out how much of the body is fat. At the same BMI, women had 10.4 percentage points more body fat than men. That's normal for a woman's body, and it's why healthy body fat ranges for women are higher.

In men, the index tracks muscle more closely. In a 2008 study by Romero-Corral and colleagues of 13,601 American adults, BMI in men matched muscle mass better, and in women it matched fat. The BMI cut-off of 30 caught obesity defined by body fat percentage in only 36% of the men who had it and in 49% of such women. So in men, the index misses excess fat more often because it responds more to muscle.

Waist cut-offs differ between the sexes. Russia's 2024 clinical guidelines treat a waist over 94 cm (37 in) in men and over 80 cm (31.5 in) in women as a sign of abdominal obesity, meaning fat around the stomach. The rule "waist less than half your height" is the same for both sexes: in the 2010 review by Browning and colleagues, the 0.5 cut-off worked for men and women in 14 countries.

Excess weight hits men harder. In the 2016 Global BMI analysis, every 5 BMI units above 25 raised the risk of death by 51% in men and by 30% in women.

BMI during pregnancy. During pregnancy, BMI isn't calculated from your current weight: it rises because of the baby, the placenta, amniotic fluid and extra blood volume. What matters is your BMI before pregnancy, since it determines how much weight is healthy to gain. In 2009, the US Institute of Medicine gave these ranges for total gain in a pregnancy with one baby:

• BMI before pregnancy below 18.5: 28–40 lb (12.5–18 kg);
• 18.5–24.9: 25–35 lb (11.5–16 kg);
• 25–29.9: 15–25 lb (7–11.5 kg);
• 30 and above: 11–20 lb (5–9 kg).

Your personal plan is set by your OB-GYN or midwife. These numbers will help you understand what they're talking about.

After giving birth. Weight after birth comes off gradually as the body recovers, and in the first months BMI says little about what's going on. It makes more sense to recalculate it and set goals once your routine settles a bit. If you're breastfeeding, talk to your doctor before cutting calories.

BMI by age: what changes after 40, 50 and 65

There's no official age adjustment for adults: the WHO and Russia's guidelines use the same 18.5–24.9 scale from age 18 for life. At the same time, Russia's 2024 clinical guidelines state plainly that BMI isn't used to diagnose obesity in older people, because it reflects the amount of fat poorly. And research shows that after 65 the safe zone shifts upward. After 40–50, the index becomes less accurate, because at the same weight the body holds less muscle and more fat.

Where "BMI by age" charts come from. The internet is full of charts that give each decade its own healthy range, but they rarely name a source, and their numbers don't agree. One such scale goes back to a 1989 report by the US National Research Council: it treated a BMI of 23 to 28 as healthy for people aged 55–65 and 24 to 29 for people over 65. Some studies of older adults still use it: Estrella-Castillo and Gómez-de-Regil, for example, compare it with the WHO scale in a 2019 paper. Neither the WHO nor Russia's clinical guidelines adopted age adjustments.

After 65. In 2014, Winter and colleagues pooled 32 studies in which almost 198,000 people over 65 were followed for 12 years on average. Compared with a BMI of 23–23.9, the risk of death was 12% higher at a BMI of 21–21.9 and 19% higher at 20–20.9. Risk started to rise only above a BMI of 33, and being overweight wasn't linked to higher death rates in older adults. The authors advise keeping an eye on weight if BMI falls below 23. The 2016 Global BMI analysis shows the same thing: every 5 BMI units above 25 raised the risk of death by 52% in people aged 35–49 and by only 21% in people aged 70–89.

What this means for you: if you're over 65 and your BMI is around 27–28, there's no need to lose weight for the sake of the number. It's more useful to keep your muscle and strength. What should worry you is something else: weight that drops on its own, without effort, especially if your BMI falls below 23. That's a reason to see a doctor.

After 40 and 50. The scale stays the same, but with age you have less muscle and more fat, even if the scale doesn't move. Jackson showed in 2002 that the link between BMI and body fat depends on age, and Romero-Corral showed in 2008 that BMI's accuracy drops with age. The extreme case is sarcopenic obesity: little muscle, a lot of fat and a BMI in the healthy range. How to spot and stop it is covered in our article on sarcopenia. That's why it's especially useful for women over 50 and men over 40 to measure their waist once a month and keep up strength training.

BMI for children and teens: why the adult chart doesn't fit

For children and teens, BMI is calculated with the same formula, but the result is compared with WHO growth curves for their age and sex.

A child is growing, and the share of fat in their body changes with age, differently in boys and girls. The same BMI at 8 and at 16 means very different things. That's why, for children and teens aged 5 to 19, the WHO uses "BMI-for-age" curves. Overweight is a BMI one standard deviation above the median for that age and sex, and obesity is two standard deviations above. Put simply, a child is compared with healthy peers of the same sex. Children under 5 have their own WHO standards. According to the WHO, 390 million children and teens aged 5 to 19 were overweight in 2022, including 160 million living with obesity.

You can calculate your child's BMI, but a pediatrician should interpret it, taking into account height, age and puberty. Don't put a child on a diet based on the adult chart: the adult scale can call healthy what is too much for their age, and the other way around.

When BMI gets it wrong: muscle, age, belly fat and ancestry

BMI gets it wrong when there's an unusual balance of muscle and fat behind the weight. In athletes, muscle pushes the number up, while in older people and in people who are slim but carry belly fat, it hides fat.

How often. In 2010, Okorodudu and colleagues pooled 25 studies with 31,968 participants and compared BMI with body fat percentage measured by accurate methods. Standard BMI cut-offs found only half of the people with excess fat. Among people without excess fat, the index wrongly labeled roughly one in ten as obese.

In the 2008 Romero-Corral study, obesity by BMI was found in 19.1% of men and 24.7% of women, but by body fat percentage measured with bioelectrical impedance it was found in 43.9% and 52.3%, about twice as often. In the BMI range of 25 to 29.9, the index couldn't tell fat from muscle in either men or women.

Athletes and people who train a lot. In 2007, Ode and colleagues measured body fat in 226 college athletes and 213 college students who didn't play sports. Excess fat was defined as more than 20% in men and more than 33% in women. Among male athletes, male non-athletes and female athletes, a BMI of 25 or higher labeled 34 to 73% of those with healthy body fat as overweight. Here's the BMI at which excess fat actually began:

• male athletes: 27.9;
• football linemen, the heaviest players on the team: 34.1;
• men who don't play sports: 26.5;
• female athletes: 27.7;
• women who don't play sports: 24.0.

The last line matters for many readers. In women who didn't train, excess fat began at a BMI of 24, which is still inside the "healthy" range, so for them the index understates the problem.

Slim, but with belly fat. In 2015, Sahakyan and colleagues followed 15,184 adults. A man with a healthy BMI of 22 and belly fat, measured by waist-to-hip ratio, had a 1.87 times higher risk of death than a man with the same BMI and no belly fat. His risk was also twice that of men who were overweight or obese by BMI but had no belly fat. Women with a healthy BMI and belly fat had a 1.48 times higher risk than women with the same BMI and no belly fat. Belly fat is often visceral, meaning it sits around the internal organs, and it's the fat most strongly linked to heart and metabolic disease. A healthy BMI doesn't rule it out.

Older adults. A person can weigh the same as at 40 while having noticeably less strength and a bigger waist. BMI won't notice, but waist size and grip strength will.

Ancestry. In people of East Asian descent, the health problems linked to obesity start at a lower weight, so Russia's 2024 clinical guidelines set lower obesity cut-offs for them: 27.5 for class I, 32.5 for class II and 37.5 for class III, and the waist threshold for men at 90 cm (35.4 in) instead of 94 cm. If you have East Asian roots, use these thresholds and talk them over with your doctor.

When BMI isn't used at all. Russia's 2024 clinical guidelines list the cases where obesity isn't diagnosed by BMI: in older people, athletes and people with very developed muscles, pregnant women, after limb amputation and with marked swelling. In all these cases, the number reflects body fat poorly, and it's better to leave the assessment to a doctor.

What to measure alongside BMI: waist, waist-to-height ratio and body fat

The simplest addition to BMI is a tape measure: your waist should be less than half your height.

Why the waist. In 2012, Ashwell and colleagues pooled 31 studies with more than 300,000 adults. Waist size alone identified people with high blood pressure, diabetes, high cholesterol and heart disease 3% more accurately than BMI, and waist-to-height ratio 4–5% more accurately. Waist-to-height ratio turned out to be more reliable than waist size alone, in both men and women.

In 2010, Browning and colleagues reviewed 78 studies and compared measures by the area under the curve. This is a number from 0.5 to 1, where 0.5 means random guessing and 1 means no errors. Waist-to-height ratio scored 0.704, waist size 0.693 and BMI 0.671. The 0.5 cut-off worked for men and women in 14 countries, including Europeans and Asians.

What doctors say. Russia's 2024 clinical guidelines call combining BMI with waist size a more accurate way to judge risk than BMI alone. An international commission in The Lancet Diabetes & Endocrinology, led by Rubino, went further in 2025. It included 58 experts, and its conclusions were endorsed by 76 medical organizations. The commission sees BMI as a tool for initial screening and for assessing whole populations, and it doesn't recommend judging an individual's health by it. It suggests confirming excess fat in one of these ways:

• a direct fat measurement, such as a DEXA scan or bioelectrical impedance;
• at least one body measurement together with BMI: waist size, waist-to-hip ratio or waist-to-height ratio;
• two such measurements without BMI.

The exception is a BMI above 40: at that weight, excess fat can be taken as confirmed. The commission also proposed telling apart clinical obesity, when excess fat is already disrupting how organs work or getting in the way of daily life, and preclinical obesity, when risk is higher but organs work normally.

How to measure your waist. Measure in the morning, standing, after a relaxed breath out, without sucking in your stomach. The tape goes horizontally, halfway between the bottom of your lowest rib and the top of your hip bone. That's how Russia's clinical guidelines describe it too. Measure at the same spot every two to four weeks. A detailed walkthrough with common measuring mistakes is in our guide on how to lose belly fat.

Body fat percentage. If you want more precision, body fat percentage can be measured with smart scales that use bioelectrical impedance, calipers or a DEXA scan. Home methods have noticeable error, but they show the trend well. Healthy ranges for women and men and a comparison of methods are collected in our article on body fat percentage.

What to do with your result: BMI below 18.5, 25 to 30 and above 30

If your BMI is above 25, measure your waist first. If it's less than half your height and you feel well, there's no rush. If it's bigger, start with a moderate calorie deficit and strength training.

BMI below 18.5. This is underweight, and in the 2016 Global BMI analysis the risk of death at a BMI of 15 to 18.4 was one and a half times higher than in the middle of the healthy range. See a doctor and find out why: low weight can come from your natural build, from thyroid or gut conditions, or from eating disorders. If you simply don't eat enough, a weight gain plan with protein and strength training will help.

BMI 18.5–24.9. Your weight fits your height. Check your waist: if it's more than half your height, you're in the "slim with belly fat" group from section 08, and strength training will do more for you than an even lower number on the scale.

BMI 25–29.9. Measure your waist. If it's under half your height and under 94 cm (37 in) for men or 80 cm (31.5 in) for women, and your blood pressure and blood tests are fine, there's no urgent need to lose weight: watch the trend and keep training. If your waist is bigger, start with a moderate calorie deficit. How to set it for yourself is shown in our guide on how to calculate a calorie deficit. In the 2016 Global BMI analysis, risk was 20% higher at a BMI of 27.5–29.9 and 7% higher at 25–27.4, so even going from 29 down to 27 is worth it.

BMI 30 and above. This is obesity by WHO standards and Russia's guidelines. Book a visit with your primary care doctor or an endocrinologist: check your blood pressure, blood sugar and cholesterol, and discuss what suits you. Weight loss medications should only be prescribed by a doctor, and buying them on advice from the internet is dangerous.

You're over 65. Your main concern should be weight loss that happens on its own, especially if your BMI falls below 23. Keep your muscles working and don't go on strict diets without a doctor.

If you decide to change your weight, the Sportygram app can help you stick to a plan (its interface is currently in Russian): the profile calculates your calorie target for your goal, the food diary with a barcode scanner and a database of about 101,000 foods tracks what you eat, and for strength training there's a workout diary with a day-by-day plan and 142 exercises with photos.

Questions and answers

The bottom line

• BMI is your weight in kilograms divided by your height in meters squared, or pounds × 703 divided by inches squared. The healthy range of 18.5–24.9 is the same for women and men from age 18, overweight starts at 25 and obesity at 30.
• Death rates were lowest at a BMI of 20–25. Mild overweight added about 7% to the risk, and class II–III obesity raised it 1.9–2.8 times.
• There's no official age adjustment for adults. After 65, a BMI below 23 is the bigger risk, and risk from excess weight rises only above 33.
• At the same BMI, a woman carries about 10 percentage points more fat. In men, the index more often confuses fat with muscle.
• BMI misses half of people with excess fat, overstates weight in athletes and can't see belly fat in slim people.
• The best addition is a waist under half your height, and by Russia's guidelines no more than 94 cm (37 in) for men and 80 cm (31.5 in) for women.

Checklist: how to check your weight in 10 minutes

• Weigh yourself in the morning, after using the bathroom, before breakfast and in minimal clothing.
• Measure your height without shoes against a wall.
• Calculate your BMI: weight ÷ (height × height), or pounds × 703 ÷ inches², or enter your numbers into the calculator.
• Find your height in the chart in section 04 and compare your weight with the healthy range.
• Measure your waist halfway between your lowest rib and your hip bone after a relaxed breath out.
• Divide your waist by your height: a result under 0.5 is good.
• If you're over 65, check whether your weight is below the limit in the last column of the chart.
• Decide what's next: change nothing, start a moderate deficit with strength training, or see a doctor.

Sources

1. World Health Organization. Obesity and overweight — fact sheet. Updated December 8, 2025. — Overweight is a BMI of 25 and above, obesity 30 and above; BMI is a surrogate marker of fatness; in 2022, 2.5 billion adults were overweight (43%) and 890 million were living with obesity (16%); among children aged 5–19, 390 million were overweight, including 160 million with obesity; cut-offs for children based on WHO curves (+1 and +2 standard deviations).
2. Dedov I. I., Mokrysheva N. G., Melnichenko G. A. et al. Obesity: clinical guidelines of the Russian Ministry of Health, 2024 version. Bulletin of Reproductive Health, 2025 (in Russian). — BMI classification for adults; obesity cut-offs of 27.5 / 32.5 / 37.5 for people of East Asian origin; abdominal obesity is a waist over 94 cm in men and 80 cm in women; combining BMI and waist is more accurate than BMI alone; BMI isn't used to diagnose obesity in older people, athletes, pregnant women, after amputation or with swelling; the waist is measured halfway between the lowest rib and the iliac crest.
3. Global BMI Mortality Collaboration. Body-mass index and all-cause mortality: individual-participant-data meta-analysis of 239 prospective studies in four continents. The Lancet, 2016. — 3,951,455 never-smokers without chronic disease: mortality was lowest at a BMI of 20–25; risk by BMI category; for every 5 units above 25, risk rose by 51% in men and 30% in women, by 52% at ages 35–49 and 21% at ages 70–89.
4. Winter J. E., MacInnis R. J., Wattanapenpaiboon N., Nowson C. A. BMI and all-cause mortality in older adults: a meta-analysis. American Journal of Clinical Nutrition, 2014. — 32 studies, 197,940 people over 65: risk of death was 12% higher at a BMI of 21–21.9 and 19% higher at 20–20.9 compared with 23–23.9; risk rose above a BMI of 33.
5. Okorodudu D. O. et al. Diagnostic performance of body mass index to identify obesity as defined by body adiposity: a systematic review and meta-analysis. International Journal of Obesity, 2010. — 25 studies, 31,968 people: standard BMI cut-offs find only half of people with excess fat (sensitivity 0.50, specificity 0.90).
6. Romero-Corral A. et al. Accuracy of body mass index in diagnosing obesity in the adult general population. International Journal of Obesity, 2008. — 13,601 adults: obesity by BMI in 19.1% of men and 24.7% of women, by body fat percentage in 43.9% and 52.3%; in men BMI tracks muscle mass more closely, in women fat; accuracy drops with age.
7. Jackson A. S. et al. The effect of sex, age and race on estimating percentage body fat from body mass index: The Heritage Family Study. International Journal of Obesity, 2002. — 665 people aged 17–65, underwater weighing: at the same BMI, women had 10.4 percentage points more body fat; the link between BMI and fat depends on age and sex.
8. Ode J. J., Pivarnik J. M., Reeves M. J., Knous J. L. Body mass index as a predictor of percent fat in college athletes and nonathletes. Medicine & Science in Sports & Exercise, 2007. — 226 athletes and 213 non-athletes: in athletes a BMI of 25 often means muscle; excess fat begins at a BMI of 27.9 in male athletes, 27.7 in female athletes, 26.5 in men and 24.0 in women who don't play sports.
9. Sahakyan K. R. et al. Normal-weight central obesity: implications for total and cardiovascular mortality. Annals of Internal Medicine, 2015. — 15,184 adults: with a healthy BMI and belly fat, the risk of death was 1.87 times higher in men and 1.48 times higher in women compared with the same BMI without belly fat.
10. Ashwell M., Gunn P., Gibson S. Waist-to-height ratio is a better screening tool than waist circumference and BMI for adult cardiometabolic risk factors: systematic review and meta-analysis. Obesity Reviews, 2012. — 31 studies, more than 300,000 adults: waist size was 3% more accurate than BMI, waist-to-height ratio 4–5% more accurate, and more reliable than waist size alone.
11. Browning L. M., Hsieh S. D., Ashwell M. A systematic review of waist-to-height ratio as a screening tool for the prediction of cardiovascular disease and diabetes: 0·5 could be a suitable global boundary value. Nutrition Research Reviews, 2010. — 78 studies; area under the curve: waist-to-height ratio 0.704, waist size 0.693, BMI 0.671; a 0.5 cut-off for men and women in 14 countries.
12. Rubino F. et al. Definition and diagnostic criteria of clinical obesity. The Lancet Diabetes & Endocrinology, 2025. — A commission of 58 experts endorsed by 76 organizations: BMI is a screening tool; excess fat is confirmed by direct measurement or body measurements; above a BMI of 40 excess fat is taken as confirmed; clinical and preclinical obesity.
13. Keys A., Fidanza F., Karvonen M. J., Kimura N., Taylor H. L. Indices of relative weight and obesity. Journal of Chronic Diseases, 1972. — 7,424 healthy men from 12 groups in five countries: weight divided by height squared is slightly better than weight divided by height in its link to height and to skinfold thickness, and simpler to calculate; the name "body mass index" is proposed.
14. Eknoyan G. Adolphe Quetelet (1796–1874) — the average man and indices of obesity. Nephrology Dialysis Transplantation, 2008. — The Quetelet index was described in 1832; the name "body mass index" was given by Ancel Keys in 1972.
15. Institute of Medicine, National Research Council. Weight Gain During Pregnancy: Reexamining the Guidelines. National Academies Press, 2009. — Total pregnancy weight gain by pre-pregnancy BMI: below 18.5, 28–40 lb (12.5–18 kg); 18.5–24.9, 25–35 lb (11.5–16 kg); 25–29.9, 15–25 lb (7–11.5 kg); 30 and above, 11–20 lb (5–9 kg).
16. Estrella-Castillo D. F., Gómez-de-Regil L. Comparison of body mass index range criteria and their association with cognition, functioning and depression: a cross-sectional study in Mexican older adults. BMC Geriatrics, 2019. — Compares the WHO scale with the 1989 US National Research Council scale, which treats a BMI of 23–28 as healthy at ages 55–65 and 24–29 after 65.

This article is for informational purposes only and is not a substitute for medical advice.