Body Weight or Fitness: Which Matters More for Health?

Body Weight or Fitness: Which Matters More for Health?

(Last Updated On: March 25, 2019)

Body Weight or Fitness: Which Matters More for Health?

What if a genie came to you and said you had a choice – you could either be fit and obese or unfit and of normal body weight? Which would you choose? In terms of health, being fit is likely your best option. Being obese is a risk factor for a number of health problems, including heart disease, Alzheimer’s disease, some types of cancer, type 2 diabetes, hypertension, stroke, sleep apnea, and infertility, but fitness may trump body weight when it comes to long-term health.

Not to underestimate the risks of being obese. Carrying too many fat cells is unhealthy because fat cells produce chemicals that produce inflammation. We now know that inflammation plays a role in a number of diseases. With all the problems obesity is linked with, is being fit really better than being fat? Believe it or not, this is a topic that’s hotly debated among researchers, nutritionists, and health care providers. What does science say about the issue?

Fitness versus Body Weight

According to a study published in 2014, cardiorespiratory fitness is more strongly linked with mortality than body fat percentage or body mass index. In other words, being fit is likely to lower your risk of dying more than losing body fat and leading a sedentary lifestyle. If you think about it, it’s not surprising. Exercise can compensate for some of the problems being overweight or obese creates.

Another study published in the Journal of the American Medical Association in 2004 also showed being fit is more important than how much you weigh. In this study, they followed 900 women for four years and found being physically inactive was a better predictor of cardiovascular events, like heart attacks, than body weight.

As mentioned, fat cells produce compounds called cytokines that cause low-grade, whole-body inflammation. It’s this smoldering inflammation behind the scenes that increases the risk for health problems like type 2 diabetes and heart disease.  In fact, John Mandrola M.D., a cardiologist refers to fat cells as “inflammation factories.”

What does this have to do with exercise and being physically fit? Research shows exercise has an anti-inflammatory effect. Remember how we said fat cells produce inflammatory cytokines? Well, there are also anti-inflammatory cytokines that help “calm the fires” and suppress inflammation. Exercise increases the production of anti-inflammatory cytokines, the most famous of which is interleukin-6 or IL-6. Research shows exercise helps protect against the very diseases, like heart disease and type 2-diabetes, brought on by inflammation.

Another problem more common in people who are overweight and obese is insulin resistance. You’re probably familiar with the role insulin plays in getting glucose and amino acids inside of cells. You need a certain amount of insulin or the cells in your body would essentially starve in the midst of plenty, plenty of glucose, that is. Insulin essentially unlocks the gates of cells to let glucose in.

On the other hand, too much insulin is problematic. Not only does insulin promote glucose uptake, it blocks the breakdown of fat. Research also suggests insulin at high levels is likely “atherogenic,” meaning it can damage the inside of blood vessels, a less than healthy situation since blood vessel injury is a forerunner to heart disease. So, you don’t want too much insulin hanging around in your bloodstream – just enough to do what it’s meant to do – escort glucose and amino acids from the food you eat into cells where they can use it to make energy.

Exercise, especially intense workouts, are one of the best ways to lower a high circulating insulin level. Physical activity works by increasing insulin sensitivity, meaning cells become more sensitive to insulin. When this happens, your body doesn’t have to produce as much insulin because the insulin you have functions more efficiently. Aerobic exercise, especially high-intensity training, improves insulin sensitivity – but so does resistance training.

Any form of activity you do is helpful for improving how sensitive your cells are to insulin. Therefore, an obese but physically fit person may not suffer from the same metabolic problems as one who’s a couch potato. Indeed, recent studies show a small portion of obese people are metabolically healthy and the chance of that is higher in those who exercise regularly.

Exercise Protects against Sarcopenia and Osteoporosis

Sarcopenia, the age-related loss of muscle and strength, and osteoporosis, loss of bone density, are two of the most common causes of disability brought on by age. Even if an obese person lost sufficient weight to be in their “healthy” range, they would likely suffer some degree of sarcopenia if they’re over the age of 50. Research clearly shows “normal weight obesity” is as much of a health problem as obesity, particularly in people who carry most of their body fat around the waist and tummy. To reduce the threat of sarcopenia, you need regular strength training. There’s really no substitute for it.

Like sarcopenia, osteoporosis causes disability.  Although there were almost 30 million women with osteoporosis in 2002, the disease is underdiagnosed. High-impact exercise to promote the laydown of new bone and heavy resistance training are two of the best defenses against osteoporosis. You don’t get this extra “perk” if you don’t exercise, no matter how lean you are.

The Bottom Line

As a Harvard health publication points out:

“Exercise isn’t going to magically erase all the health risks of being heavy. If you are lean, it’s worth the effort to stay that way. And if you’re heavy, it’s a good idea to hop on the scale and try to lose some of that weight”

The good news is exercise can help you lose weight when you combine it with a clean diet of whole, unprocessed foods and lots of vegetables and lean sources of protein. Even if genetics are strongly working against you, losing as little as 10% of your body weight can have a big impact on your health. Combine it with exercise, both aerobic and resistance training, and your chances of staying healthy are higher.

What if you never get down to a healthy body weight? Even if you never manage to lose the weight, being physically fit will give you added protection against obesity-related diseases. Being fit is vital to long-term health and well-being, regardless of how much you weight or how your body fat percentage.



Curr Sports Med Rep. 2015 Jul-Aug;14(4):327-32. doi: 10.1249/JSR.0000000000000170.

Dr. John M. “Fat cells as Inflammation Factories”

National Heart, Lung, and Blood Institute. “What Are the Health Risks of Overweight and Obesity?”

JASN November 1, 2004 vol. 15 no. 11 2792-2800.

Today’s Dietitian. Vol. 13 No. 1 P. 14. January 2011.

Journal of Applied Physiology Published 1 April 2005 Vol. 98 no. 4, 1154-1162 DOI: 10.1152/japplphysiol.00164.2004.

Rev Esp Cardiol. 2012;65:309-13. – Vol. 65 Num.04 DOI: 10.1016/j.rec.2011.11.009.

American Academy of Orthopedic Surgeons. “Osteoporosis and bone health”

Harvard Health Publications. “Is it okay to be fat if you’re fit?”


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