Fitness May Matter More Than Weight Loss for Health and Longevity

Dec. 28, 2021 — Numbers are easier. That may be why a person’s weight — and the desire of millions of people to lose weight — is the first topic under discussion when it comes to health and longevity. Not long after you walk into your doctor’s exam room, for example, you’ll step on a scale. It’s usually the first measurement they take, ahead of vital signs like blood pressure and heart rate.

This makes sense. It’s a number, which means it’s easy to see if your weight has changed in either direction since the last time they weighed you.

But there’s an unintended result: You come away thinking that your weight is every bit as important as how well your heart and blood vessels are working, and that losing a few pounds will improve your health in tangible, long-lasting ways.

Yes, weight loss has proven health benefits. But should weight loss be the top priority for everyone classified as “overweight” or “obese” — a demographic that now includes three-quarters of all American adults?

“The weight loss message is not, and has not been, working,” says Glenn Gaesser, PhD, a professor of exercise science at Arizona State University.

He’s among a growing number of health experts who believe that weight loss may not be the most important benefit when it comes to adopting a healthier lifestyle. That’s especially true if you compare it to the benefits of increasing your fitness level, as Gaesser and a co-author did in a recent study.

Intentional weight loss — that is, losing weight on purpose, rather than because of an injury or illness — is usually associated in studies with a lower risk of death from any cause. The effect is most powerful among those with obesity and/or type 2 diabetes.

But here’s an interesting wrinkle: The amount of weight lost doesn’t seem to change the risk of dying. If the weight itself is the problem, why wouldn’t those who lost the most get the biggest risk reduction?

Gaesser is skeptical that the health benefits of weight loss are entirely or even mainly caused by a lower number on the scale. Many clinical weight loss trials — studies in which people take part in a structured program — also include exercise and diet components.

Moving more and eating better are consistently and strongly linked to less risk of death from any cause. And “the health benefits of exercise and diet are largely independent of weight loss,” Gaesser says.

That’s especially true for exercise and living longer. Studies show that increasing physical activity lowers the risk of death from any cause by 15% to 50%, and the risk of heart disease by up to 40%.

The change is even more dramatic when you exercise with enough effort to improve your heart fitness. Moving from the lowest fitness category to a higher one can cut your mortality risk by 30% to 60%.

The Challenge of Sticking With It

But here’s the rub: Exercise only helps if you do it, and a higher level of fitness works best if you maintain it.

“Adherence to exercise is just as challenging as adherence to diets,” Gaesser says. “I think one of the reasons is that exercise has been promoted primarily as a means to lose weight.”

It’s not that exercise is doesn’t work at all if you’re trying to lose weight. According to a review of studies published in the 2010s, average weight loss ranges from 3 to 8 pounds, mostly from fat loss.

The problem is that the amount of weight you lose strictly from exercise tends to be disappointing. Your body will make up for many of the calories you burn during exercise (28%, according to one study) by slowing down your metabolism in other ways. Exercise can also increase your appetite, knocking any calorie savings for a loop.

“If a person starts an exercise program with a particular weight loss goal, that person will quickly see there’s a huge gap between ‘actual’ and ‘expected’ weight loss,” Gaesser explains. “Most will give up out of frustration.”

That’s why he says our best hope is for people to finally realize just how important movement is to long-term vitality, and for doctors and other health professionals to encourage their sedentary patients and clients to exercise for their health and for a longer life. Still, he acknowledges that exercise tends to be a tough sell once you take the promise of weight loss off the table.

If there’s an encouraging takeaway, it’s this: It doesn’t matter why you exercise, or how you do it, or if you fall short of your goals.

“There are health benefits to making the effort,” Gaesser says. “Exercise has intrinsic value, regardless of changes in body weight.”