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Peter Attia Just Busted These Longevity Myths

Spoiler: Your BMI could be B.S.

While blood-swapping billionaires and testicle ice baths are going viral, it’s hard to tune out the noise and dial into legit, life and healthspan-extending advice. The solution? Turn to the experts. 

Peter Attia, M.D., sat down with Quest Nutrition co-founder Tom Bilyeu on a recent episode of the Impact Theory podcast to dispel three longevity and healthspan myths. His answers may surprise you. 

Myth: Diet is a Cure-All 

Eating healthy can mitigate your risk for chronic illness, obesity, and digestive issues, per the Centers for Disease Control (CDC), but Attia warns that diet isn’t the cure-all many think it is.

“Nutrition has far more downsides if you get it wrong, than upsides if you get it right,” Attia explains. “If you [eat right] at the exclusion of other things, like exercise, you’re really leaving an opportunity on the table. Unlike nutrition, if you get exercise right there are enormous upsides. There is true life extension and remarkable healthspan extension.”

Research backs him up. Exercise may be associated with better health outcomes than losing weight and dieting in obese people, according to a 2021 review of over 200 studies (1). Researchers found that obesity-related mortality and cardiometabolic risk is eliminated with moderate-to-high levels of cardiorespiratory fitness or physical activity, independent from weight loss.

Attia recommends pairing a high-protein diet with resistance workouts to build and preserve lean muscle mass.

Myth: Lean People Have Great Metabolic Health

Obesity is the top risk factor for developing type 2 diabetes, and up to 90 percent of diabetics are overweight (2). But Attia points to data that suggests being a lean diabetic is more dangerous than being an obese one. 

Lean diabetics tend to have fat concentrated around the viscera—the soft organs in your body—which “doesn’t translate to much weight on the scale,” Attia explains.

“Lean diabetes” is associated with an increased risk of hypoglycaemia (low blood sugar) and death (3). One 2012 study found that lean diabetics were more than twice as likely to die compared to their obese counterparts. 

Researchers call this the “obesity paradox”—when excess fat appears to have a protective effect against diabetes-related mortality (4). However, the exact cause is still being studied.

“You don’t need much of that fat in total mass to cause absolute metabolic destruction,” Attia says. “That’s why the lean person who is metabolically unhealthy has the worst outcome.”

Myth: BMI Indicates How Healthy You Are

The Body Mass Index (BMI) scale is a population-based metric that measures the ratio of your height to your weight, irregardless of body composition. Meaning: An overweight person and a lean, muscular person of the same height and weight have the same BMI. 

Many physicians rely on BMI to assess obesity-related risk factors for conditions like cardiovascular disease, type 2 diabetes, and all-cause mortality. 

But BMI alone can’t diagnose your health. 

“Up to a third of people who meet the BMI criteria for obesity are metabolically healthy,” Attia says. “And their life expectancy is the same as a lean person.”

While research shows that the BMI scale is fairly accurate in predicting risk for obesity-related conditions, like cancer and cardiovascular disease at the population level, it’s not an indicator of overall health in individuals (5). 

“There are reasons not to be obese that go beyond premature cardiovascular disease, cancer, etc,” Attia says. “I don’t want to suggest that body composition doesn’t matter. The reason I’m not a fan of population-based metrics like BMI is they just don’t contain enough information.”

Instead of BMI, Attia says he uses his patients’ visceral and total fat, bone mineral density, and lean muscle mass to determine whether or not they are obese.