What's a Healthy Weight for You?

Typically, health experts evaluate weight using the body mass index, or BMI, a measure calculated from height and weight that correlates with the amount of body fat someone has. (You can find many BMI calculators online, including on the Centers for Disease Control and Prevention website.) A result below 18.5 is considered underweight, 25 to 29.9 is overweight, and 30 and above is obese.

The conventional wisdom is that as the BMI rises, so does the risk for weight-related health conditions and dying early. But researchers have speculated that the standard BMI curve—with mortality going up as BMI does—may be more U-shaped for older adults.

As it turns out, those with low or very high BMIs are at greater risk of illness and dying early, and those who are a healthy weight, overweight, or even mildly obese sit in the sweet spot in the middle. A 2022 study of 1,051 men and women whose average age was 77, published in the Annals of Geriatric Medicine and Research, found that those with a BMI below 25 or above 35 had a higher risk of balance problems, falls, malnutrition, and poor strength. The researchers set “optimal” BMI ranges for people over age 65 at 31 to 32 for women and 27 to 28 for men.

Knowing your BMI tells you whether you might be carrying extra pounds. But it doesn’t tell you how much muscle you have or where the fat is located, two factors that are important in determining whether you need to lose weight.

With age, the amount of fat you have increases and the amount of muscle decreases. This age-related loss of muscle, called sarcopenia, is associated with a higher risk of falls, frailty, and early death. In addition, that extra fat may accumulate in the midsection (called visceral fat) and infiltrate muscles and organs, such as the liver. This shift, which happens regardless of the BMI, contributes to an increased risk of heart disease, type 2 diabetes, liver disease, and more.

That’s why some researchers point to body composition testing, which determines the percentage of body fat, as a way to get a more accurate idea how weight could be affecting health. A 2020 review published in Frontiers in Nutrition found that “evidence supports the role of low lean mass [i.e., muscle] as the actual predictor of mortality when used in place of BMI.”

There are easy ways to figure out where you stand in terms of body fat and muscle.

First, measure your waist circumference, which will help you see if you’re carrying too much visceral fat. Place a tape measure around your middle, just above your hip bones. If the number is greater than 40 inches for men and 35 inches for women, your disease risk is higher.

An inexpensive way to measure body fat is to use skinfold calipers (available at many gyms). But a DXA (dual X-ray absorptiometry) scan, which your doctor may have already recommended to test bone density, can tell you how much fat and muscle you’re carrying and estimate the amount of visceral fat. So if you’re getting a DXA scan for your bones, ask for those results. According to the American College of Sports Medicine, a poor result for people ages 60 and over is a body fat percentage greater than 25.7 for men and over 30.9 for women. (Note: Scales that measure body fat might not give accurate results, CR’s tests have found.)

Next, with these numbers in hand, consider your health and lifestyle. Are you in good health or are you trying to manage one or more chronic conditions, such as heart disease, diabetes, COPD, or osteoarthritis? Do you have trouble moving around because of excess weight or can you do all the things you want to do, such as playing with your grandkids, volunteering, or just sleeping soundly? “Focusing on these factors is a better approach for evaluating if you need to lose weight than focusing on what the scale says alone,” says Laura Mosqueda, MD, a professor of family medicine and geriatrics at the Keck School of Medicine of USC in Los Angeles.

For example, if you’re 5 feet, 6 inches and weigh 160 or 170 (a BMI of 25.8 or 27.4, respectively); your waist size is within the guidelines; and you’re active and healthy, you probably don’t need to worry about losing weight. But if you have underlying health conditions or you’re carrying excess pounds around your middle, you may be better off trying to drop some weight. If necessary, your doctor can help you determine how weight changes could affect your health.

“What we really want people to have if they’re going to be heavier is lean body mass, not fat mass,” Lloyd-Jones says. “Just as fat is metabolically active in bad ways, muscle is very metabolically active in good ways. It clears blood sugar and harmful fats out of the blood very quickly.”

Strength training—using dumbbells, weight machines, exercise bands, and your own body weight as resistance—is the primary way to preserve and build muscle. “Working with some sort of coach, physical therapist, or trainer is a good way to figure out what to do and where to start,” Mosqueda says. “Your workout needs to be individualized for your goals and what’s important to you so things are designed in ways that are meaningful to you.”

Aim for two weekly strength-training sessions that target your entire body. Moderate-to-vigorous aerobic exercise—walking, jogging, cycling, climbing stairs, swimming—can also help keep muscles strong and help reduce fat, along with healthy eating. Even if you don’t lose pounds, you can change your body composition by reducing fat and increasing muscle.

Protein is also key for building and maintaining muscle, says Rosanne M. Leipzig, MD, PhD, a professor in the department of geriatrics and palliative medicine at the Icahn School of Medicine at Mount Sinai in New York. “Older people don’t eat as much protein as they should, and that’s a big problem,” she says. While the standard daily need for protein is 0.36 gram per pound of body weight per day, people over age 65 should strive for 0.45 to 0.68 gram of protein per pound of body weight daily, or about 72 to 109 grams for a 160-pound person. To maximize your body’s ability to absorb and use protein, spread it throughout the day instead of eating it all in one meal.

Editor’s Note: This article also appeared in the April 2023 issue of Consumer Reports On Health.

Weighing yourself regularly is a good way to spot and address lifestyle changes you may need to make. These scales (shown in alphabetical order) from CR’s tests have helpful features.