A new study appearing online Dec. 5 in the journal Circulation finds that improving or even just maintaining your fitness level can help you live longer, regardless of whether your body weight has stayed the same or even gone up.
"We all tend to assume that it's weight loss and obesity and seeing a change in pounds that is having the true effect on overall cardiovascular disease and, ultimately, mortality," said Dr. Tara Narula, a cardiologist with Lenox Hill Hospital in New York City. "For these researchers to draw the conclusion that really it's fitness that may have more of an impact than seeing actual changes in pounds, that's big news."
Narula was not involved with the study, which was funded by the U.S. National Institutes of Health and the Coca-Cola Co.
Given that two-thirds of the U.S. population are overweight or obese, the observation could change the way millions approach health.
"It means that we can tell people to continue to exercise even if they're not seeing changes overtly physically," Narula continued. "It can be disheartening for people exercising and dieting to not see results. Being able to say its effects are going on at a level that you may not visibly see may translate into long-term outcomes; that's a powerful message."
So, to live longer you need to exercise more even if you're not shedding pounds.
These researchers looked at cardiorespiratory fitness as measured by metabolic equivalents (METs), an indication of how often a person engages in aerobic exercise and how fit they are.
The METs were measured from a treadmill test.
The study followed more than 14,000 well-off, middle-aged men for 11 years, finding that those who maintained their fitness levels reduced their odds of dying from cardiovascular disease or any other causes by about 30 percent even if they failed to lose any excess weight.
Those who improved their fitness levels over the decade or so of the trial slashed their odds by about 40 percent.
But men whose fitness declined over this time had a higher risk of dying. And body-mass index (BMI) — a measurement that takes weight and height into account — was not associated with mortality.
Fitness, in turn, was highly correlated with how much a man exercised.
"Maintaining or improving fitness was significantly associated with a lower risk of mortality, and the man who lost fitness had a higher risk of mortality regardless of changes in body-mass index," said study author Duck-chul Lee, a physical activity epidemiologist with the department of exercise science at the University of South Carolina's Arnold School of Public Health in Columbia. "People need to [think] more about their fitness, and not just their fitness but trying to improve or maintain their fitness rather than focusing too much on weight loss or worrying too much about weight gain."
There were some limitations to the study. For one thing, BMI is not necessarily the best measure to use as it doesn't take into account body composition, cautioned Dr. Jonathan Whiteson, medical director of the Cardiac and Pulmonary Wellness and Rehabilitation Program at NYU Langone Medical Center in New York City.
Lee, however, noted that the group had similar results when they measured body fat in a subsample of men. In other words, fit men lived longer even if their body fat hadn't changed.
It's also not clear if the results can be extrapolated to minorities or other populations or to obese people, given that virtually all participants in the trial were normal weight or overweight.
But, said Whiteson, "The key fact here is that aerobic exercise reduces your risk factors for cardiovascular events. . . These were pretty impressive numbers."
"I don't think the fact that Coca-Cola funded this should be an issue," Narula said. "It's a well-conducted study that tried to remove any variables. I don't think that having Coca-Cola as a sponsor should in any way alter how we interpret the results."