There’s no single number that works for everyone. Your ideal weight depends on your height, age, sex, body composition, and ethnic background. The most common starting point is BMI (body mass index), which defines a “healthy weight” as a BMI between 18.5 and 24.9. For a person who is 5’6″, that translates to roughly 115 to 154 pounds. For someone 5’10”, it’s about 129 to 174 pounds. But BMI is just one piece of the picture, and for many people, it’s not the most accurate one.
What BMI Tells You (and What It Misses)
BMI divides your weight in kilograms by your height in meters squared. Both the CDC and the World Health Organization use the same adult categories:
- Underweight: below 18.5
- Healthy weight: 18.5 to 24.9
- Overweight: 25 to 29.9
- Obesity: 30 or higher
For children and teens, BMI is interpreted differently. Instead of fixed cutoffs, a child’s BMI is compared to others of the same age and sex. Obesity in kids is defined as a BMI at or above the 95th percentile.
The problem with BMI is that it can’t distinguish between muscle and fat. Muscle is denser than fat, meaning it takes up less space for the same weight. Someone who strength trains regularly could land in the “overweight” category while carrying very little excess body fat. As the Cleveland Clinic explains, an extra 15 pounds of muscle makes you look firmer and leaner, while an extra 15 pounds of fat takes up considerably more space. If you’ve been exercising and the scale creeps up, you may actually be getting healthier, not less so.
Why Ethnicity Changes the Cutoffs
Standard BMI thresholds were developed largely from data on white European populations, and they don’t apply equally to everyone. Research published in The Lancet found that Asian populations generally carry a higher percentage of body fat than white populations at the same BMI. This means health risks like type 2 diabetes and cardiovascular disease start climbing at lower BMIs in many Asian groups.
The WHO expert consultation identified that increased risk begins at a BMI as low as 22 in some Asian populations, compared to 25 in the standard framework. Practical action points of 23 and 27.5 were proposed as alternatives to the standard 25 and 30 cutoffs. If you’re of South Asian, East Asian, or Southeast Asian descent, a BMI that looks “normal” on a standard chart may still warrant a closer look at your metabolic health.
Your Waist May Matter More Than Your Weight
Where you carry fat is often more important than how much you weigh overall. Fat stored around your midsection, known as visceral fat, wraps around internal organs and drives up the risk of heart disease, type 2 diabetes, and metabolic problems far more than fat stored in your hips or thighs.
The simplest check is your waist-to-height ratio. The NHS recommends keeping your waist measurement below half your height. If you’re 5’8″ (68 inches), your waist should ideally stay under 34 inches. To measure, wrap a tape measure around your midsection at the level of your belly button, standing relaxed without sucking in. This takes about 10 seconds and gives you a better snapshot of metabolic risk than stepping on a scale.
Body Fat Percentage by Sex
Men and women carry fundamentally different amounts of fat, which is another reason a single weight number is misleading. Women need more essential fat for hormonal function and reproductive health.
There’s no universally agreed-upon “ideal” body fat range, but research from Harvard Health provides useful benchmarks. For men, a body fat percentage of 25% or higher is considered overweight, and 30% or higher is classified as obese. For women, those thresholds are 36% and 42%, respectively. Athletes typically fall well below these numbers, while people who exercise moderately tend to sit somewhere in the middle.
You can get a rough body fat estimate from a smart scale at home, though these aren’t highly accurate. More precise options include DEXA scans (a type of low-dose X-ray) and hydrostatic weighing, which some gyms and clinics offer.
Healthy Weight Shifts as You Age
The “ideal” BMI for a 30-year-old isn’t necessarily ideal for a 70-year-old. Older adults who fall in the overweight BMI range (25 to 29.9) consistently show better health outcomes than those at a “normal” BMI. A UCLA Health study examining older surgical patients found that overweight individuals had a 30-day mortality rate of just 0.8%, compared to 18.8% for those with a normal BMI and 15.0% for underweight patients.
The reasons aren’t fully settled, but carrying some extra weight in later life appears to provide a metabolic reserve during illness, surgery, or periods of reduced appetite. Losing too much weight after 65, particularly muscle mass, can be more dangerous than carrying an extra 10 or 15 pounds. This is why many geriatric specialists focus less on the number on the scale and more on maintaining strength and function.
Weight Versus Metabolic Health
Two people can weigh exactly the same and have completely different health profiles. Researchers use a set of metabolic markers to determine whether someone’s weight is actually causing harm. These include blood pressure, fasting blood sugar, triglycerides, HDL cholesterol (the protective kind), and markers of inflammation and insulin resistance. If fewer than two of these are abnormal, a person is generally considered metabolically healthy, regardless of BMI category.
This matters because some people with a BMI over 30 have perfectly normal blood work, good blood pressure, and no signs of diabetes. Meanwhile, some people at a “normal” weight carry dangerous amounts of visceral fat and show early signs of metabolic disease. The American Association of Clinical Endocrinology now stages obesity based on complications rather than weight alone. Stage 1 means obesity with no related health problems. Stage 2 includes mild to moderate complications like prediabetes, borderline high cholesterol, or mild sleep apnea. Stage 3 involves severe complications that significantly impact quality of life.
This staging system reflects a broader shift in how clinicians think about weight. The number itself is less important than what it’s doing to your body.
A Practical Way to Assess Your Weight
Rather than fixating on a single target weight, consider these measures together for a more complete picture:
- BMI: a useful starting screening tool, especially if you’re between 18.5 and 24.9, but less reliable if you’re muscular, older, or of Asian descent
- Waist-to-height ratio: keep your waist below half your height for the lowest metabolic risk
- Body fat percentage: aim below 25% for men, below 36% for women, though these thresholds vary by age and fitness level
- Metabolic markers: normal blood pressure, blood sugar, and cholesterol matter more than the scale
If your BMI is in the healthy range, your waist is proportional to your height, and your blood work looks clean, your weight is likely fine, whatever the number happens to be. If one or more of these measures is off, that’s a more meaningful signal than any weight chart can provide.