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Are You Fit Enough to Withstand Cancer?

A new study finds that fitness makes individuals more resistant to cancer.
(Photo: Kzenon/Shutterstock)

(Photo: Kzenon/Shutterstock)

Once again, we have confirmation that fitness really does pay off. In new study published in JAMA Oncology, a team of researchers find that middle-aged men and women with a high level of cardiovascular fitness reduced the risk of colorectal cancer by 44 percent and lung cancer by 55 percent. In fact, among those diagnosed with cancer at Medicare age, the fittest among the group had a 68 percent reduction in cardiovascular disease mortality.

In other words, being fit can reduce your risk of dying from a painful death. So, how did they evaluate "fitness"?

Cardiovascular fitness was evaluated on a treadmill test and measured by Metabolic Equivalent of Task, a common way of ranking the difficulty of exercise. One "MET" is complete rest, carrying a heavy load is 7.5 METs, and fast bicycling is 10 METs. An individual's MET score is often judged by how hard they can exercise before succumbing to exhaustion and giving up.

To get a better handle on how to think of MET-measured fitness, researcher Susan G. Lakoski explained that someone with the lowest level of cardiovascular fitness would probably take longer than 12 minutes to jog a mile. More importantly, improving one's fitness the equivalent of shaving about a minute off a mile would significant improve their chances against cancer.

Increased oxygen improves blood flow to tumors, supercharging the effect of chemotherapy treatment.

"Even a small improvement in fitness (by one MET) made a significant difference in survival - reducing the risks of dying from cancer and cardiovascular disease by 10 and 25 percent," Lakoski told Reuters.

Likewise, the highest level of cardiovascular fitness was judged to be greater than 11 METs, or someone that could sustain exercise of very fast running (i.e. an eight-minute mile).

This study dovetails with recent experimental evidence that exercise itself can aid in cancer treatment. Increased oxygen improves blood flow to tumors, supercharging the effect of chemotherapy treatment. This particular study was done on mice, so it's unknown how much exercise a human would need to do to combat a growing cancer. But, it was helpful in understanding the mechanism by which fit individuals make themselves immune to tumors.

Taken together, both studies provide a nice frame to think about how to live a healthy life. Being healthy is more about fitness than how one looks in the mirror. A new book, Body of Truth, provides good context here, arguing that people should basically stop trying to lose weight. After all, people often rebound poorly from extreme diets, and the health effects of losing weight are inconsistent.

Dieters can often cheat weight loss by starving themselves, eating highly processed low-calorie foods, or other behaviors that help them lose weight in unhealthy ways. Fad diets and heavily marketed diet pills mean that weight loss, alone, may not increase one's lifespan or resistance to disease.

So while it may be harder to identify the benefits of less body fat, cardiovascular fitness definitely has benefits. It's difficult to be overweight, eat terribly, and attain the highest level of physical fitness. It's not easy to run an eight-minute mile carrying 50 extra pounds of body fat and trying to digest a super burrito.

In other words, your suspicions are correct: The most physically fit are often both slimmer and healthier.