Glenna Ganster has tussled for years with the unwanted 10 to 15 pounds she acquired after menopause.
She and her husband tried intermittent fasting, severely restricting calories three days a week and eating as they pleased the other four. It took the weight off, but after two years, “we both just got tired of it,” she said. The pounds returned.
Now Ms. Ganster, 72, a retired mental health counselor in Tucson, has ramped up her exercise routine, adding cardio and squats to her usual weight training and walking three to four miles daily. To appease her sweet tooth, she bakes brownies containing black beans and cookies with chickpeas.
She feels “a little tempted,” she said, by the GLP-1 medications so many people take to lose weight.
Her doctor insists her current body mass index of 25.7, barely above normal, indicates a healthy size and discourages her interest in obesity drugs. “He said: ‘You’re fine, you’re absolutely fine. Don’t worry about it,’” she said.
Still, hanging reproachfully in her closet are clothes she wore 30 years ago and wants to wear again. “I don’t want to look like my mother or my grandmother,” she said.
Yet researchers have reported for years that older people who are overweight or obese, with a higher B.M.I., live longer than those with a normal body mass index. I shared this apparently little-known finding with Ms. Ganster.
“You made my day,” she said.
Known as the obesity paradox, this relationship upends a message Americans have heard for decades: that obesity increases the risk of heart disease and stroke, Type 2 diabetes, a number of cancers and other potentially lethal illnesses.
It does indeed, for the young and middle-aged. “The picture isn’t the same once we get to older adults,” said Bryan Blissmer, a health researcher at the University of Rhode Island and a co-author of the most recent study reporting that inverse relationship, published in the Journal of the American Geriatrics Society.
“Past age 65, a higher B.M.I. is linked to greater longevity,” he said, though with certain caveats about where people carry that weight.
Body mass index, a ratio based on height and weight, is categorized as normal between 18.5 and 24.9. People with a 25 to 29.9 B.M.I. are deemed overweight; at 30 to 39.9, they’re considered obese.
For a man who is 5 feet 8 inches, the average height for American men over 65, a normal weight is 122 to 164 pounds, while over 164 to 197 pounds is overweight. A 5-foot-3-inch woman over age 65, also the average height, has a normal B.M.I. if she weighs 105 to 141 pounds and is overweight at over 141 to 169.
Early on, researchers documented the counterintuitive longevity benefit mostly for older patients with a variety of illnesses. “Is obesity harmful no matter what?” said Dr. Kamyar Kalantar-Zadeh, a nephrologist and epidemiologist at Harbor-U.C.L.A. Medical Center.
His studies found that it wasn’t. “When we face hardship, including people with kidney disease who need dialysis to survive, being overweight or obese can help,” he said.
Dr. Kalantar-Zadeh’s studies found similarly reduced mortality for heavier seniors with coronary artery disease and heart failure; other researchers have reported survival benefits for overweight or obese older patients with certain cancers, including colon cancer. “The older you are, the survival advantage of being obese increases,” Dr. Kalantar-Zadeh said.
Broader studies using nationally representative samples of older Americans have also found a survival advantage. The University of Rhode Island study included about 6,900 people age 65 and older, controlling for variables like race, education, income and smoking history.
The researchers reported that men who were overweight or in the lower categories of obesity were about half as likely to die, over a 14-year period, as men with a normal B.M.I. Although the effect was less pronounced among women, overweight women had a 27 percent lower mortality rate.
Extreme obesity, having a body mass index above 40, does mean a higher mortality risk. But the greatest risk, studies have demonstrated, occurs among older people who are underweight, with a B.M.I. below 18.5.
The reason an above-normal weight is associated with longevity remains a point of debate. Nutritional reserves might help older people survive health setbacks, which occur more commonly at older ages. Or the paradox might reflect survivorship bias, because “individuals with diseases related to obesity may have already passed away,” Dr. Blissmer said.
Moreover, B.M.I. alone “is a very incomplete measure” that doesn’t determine other relevant health factors like muscle mass and bone mass, said Dr. Sei Lee, a geriatrician and researcher at the University of California, San Francisco.
Lest older Americans conclude that a pizza a day will keep the doctor away, one element of body size does correlate with higher mortality: where the extra weight is carried. In the University of Rhode Island study, both men and women with higher waist circumferences (above 35 inches for women or 40 inches for men) were more likely to die regardless of their B.M.I.
“The fat stored in your abdomen is more biologically active” than fat in the hips, chest or buttocks, Dr. Blissmer explained. “It has a greater association with insulin resistance, inflammation, elevated cholesterol and Type 2 diabetes.” The influential Lancet Commission, which convenes experts to advise on health practices and policies, has recommended using additional metrics like waist circumference, instead of B.M.I. alone, to diagnose obesity.
Dr. Blissmer and his colleagues are now looking beyond longevity to how higher weight relates to health and quality of life; they expect to publish their findings within a year.
Meanwhile, many older Americans carrying a few extra pounds don’t need to fixate on the number on the scale, Dr. Lee said. “As you get older, the risks of being heavier go down,” he said.
“As a doctor, one thing that always makes me sit up straight is when an older adult’s weight is changing substantially in either direction,” he added. He advises his patients to eat healthily and exercise “because it improves your quality of life,” he said, even if it doesn’t allow them to fit into their old jeans.
Yet changing people’s attitudes toward body size can prove difficult. “These social pressures are pervasive and incredibly powerful,” Dr. Lee acknowledged.
Liz Llorente, 66, a public relations professional in Oakland, N.J. said she has felt them for most of her life as her weight has moved “up and down, up and down.”
She recently rejoined Weight Watchers, counting points and hoping to drop from a Size 12 back to a 10 or an 8. Although her doctors have expressed no concern, “I have a mirror,” she said. “I have a scale.”
She recognizes that “there’s what Hollywood says and then there’s what science says,” she added. Still, “I feel better if my clothes aren’t tight.”
The New Old Age is produced through a partnership with KFF Health News.