Can You Outrun Your Diet?

Caucasian woman running on city street
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Yes, it is true that exercise is the magic pill, but can even the best level of physical fitness save you from the worst dietary habits?

Exercise Isn’t Enough

In an editorial in the British Journal of Sports Medicine in April 2015, researchers argued that exercise alone--no matter how good it is for preventing cardiovascular disease, type 2 diabetes, some cancers, and even dementia—is not enough to treat or prevent obesity, or to overcome the damage done by a bad diet.

As these researchers note: “In the past 30 years, as obesity has rocketed, there has been little change in physical activity levels in the Western population.  This places the blame for our expanding waistlines directly on the type and amount of calories consumed.”

The Health Consequences of Junk Food

These authors also note that the obesity epidemic “represents only the tip of a much larger iceberg of the adverse health consequences of a poor diet.” Noting that poor diet in and of itself “now generates more disease than physical inactivity, alcohol and smoking combined,” the authors point to the observation that up to 40% of people with a normal body mass index (BMI) will be found to have metabolic abnormalities such as high blood pressure, fatty liver disease, and cardiovascular disease because of poor diet alone, even if they are not overweight or obese.

Further, the authors take the food industry to task, stating that its “Public Relations machinery” is responsible for drowning the public in an “unhelpful message about maintaining a ‘healthy weight’ through calorie counting, and many still wrongly believe that obesity is entirely due to lack of exercise.” The authors’ editorial message: even if your weight is normal, and even if you exercise on a regular basis, poor diet can hurt you.

Athletes at Risk for Diabetes

These authors go on to point out that even elite athletes who engage in “carb loading” are at risk for developing type 2 diabetes later in life if they continue to eat such high-carb diets for decades, because these diets are known to worsen insulin resistance, which in turn leads to diabetes.

This is of particular interest, since celebrity athletes are often pictured in commercials and other advertising as being associated with some sugary beverage (soft drink, energy drink, etc.) or unhealthy snack food. The image projected may present the idea that such poor dietary habits are okay as long as you work out or exercise to the level of an elite athlete, but as noted above, even such elite athletes are at risk for chronic metabolic diseases like diabetes and heart disease down the road if they engage in poor eating habits, no matter their level of physical fitness.

Take-Home Message

The take-home message here is clear: exercise and diet go hand in hand. All-around good health cannot be maintained if one is present without the other. Time to get rid of the all-too-common thinking that running a mile entitles you to an extra blueberry muffin. Run that mile and stick to whole blueberries instead.


Malhotra A, Noakes, T, Phinney S. Editorial: it is time to bust the myth of physical inactivity and obesity: you cannot outrun a bad diet. Br J Sports Med 2015. doi:10.1136/bjsports-2015-094911.

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