You Can’t Out-Train a Bad Diet, But Exercise Sure Does Help

While it’s true that you can’t out-exercise a bad diet, that doesn’t mean exercise doesn’t help. A new study explored the effects of high-intensity exercise on your lipid profile.

There’s an adage in fitness circles that no amount of exercise can overcome a bad diet. This saying is usually in reference to weight loss, but is generally a good rule to live by anyway. Good eating is a cornerstone of health, longevity, and fitness. But as far as lipid profiles go, it seems a lot can be accomplished by intense exercise as well. So says a recent study in the Journal of the International Society of Sports Nutrition.

Lipid profile typically refers to the levels of various lipids in the blood. While most people think of fat when they hear the word lipids, the term actually refers to a whole class of substances that have a major role in human health and performance. The list of lipids includes fats and oils, as well as phospholipids (what your cell walls are made out of), sterols (like cholesterol), glycerides (like triglycerides), and fat-soluble vitamins (like vitamin D).

Often included in lipid profiles is a hybrid molecule called a lipoprotein. Lipoproteins are exactly what they sound like, a mixture of both lipids and proteins. Lipids themselves are largely hydrophobic, which means they don’t play well with water. Since your blood has a lot of water in it, lipids have a tough time getting around on their own. Thus we have lipoproteins, hybrid molecules that carry lipids around and help move them in and out of cells. Lipoproteins are even shaped like little fat-carrying fortresses.

We’ve all heard the terms HDL (high density lipoprotein) and LDL (low density lipoprotein) in reference to cholesterol, but this is a bit of a mistake. Cholesterol is a separate type of lipid, not a lipoprotein, but the high density and low density varieties of lipoprotein tend to function as cholesterol carriers, for reasons mentioned above. One of the many functions of cholesterol is to increase the viscosity (the thickness of the fluidity) of your cell membranes. The low density variety of lipoprotein trucks the cholesterol to your cells, and thus is considered “bad.” The high density kind takes cholesterol away from your cells, so we call it “good.”

High HDL, especially relative to LDL, has been shown to reduce the risk of cardiovascular disease. It was one of the most important features of the lipid profile in today’s study. The researchers studied female volleyball players who were about to begin a season. They took a blood sample of the players before their eleven-week preseason, and then again afterward. During the preseason, the players trained or played six days per week, often twice per day, a rigorous schedule.

The researchers also analyzed the diets of the players, which they found to be high in saturated fats and cholesterol. The athletes didn’t achieve the recommended ratio of unsaturated fats to saturated fats. But despite the poor lipid content of their food, the players’ lipid profiles improved after the eleven week preseason. The LDL levels dropped, as did the ratios of bad lipoproteins to good, and the HDL levels increased, indicating they were healthier.

While you can’t overcome a bad diet, according to this study it seems that hard training can reduce your risk factors of heart disease.  This is even better news for people who eat a healthy diet and exercise.


1. Juan Mielgo-Ayuso, et. al., “Changes induced by diet and nutritional intake in the lipid profile of female professional volleyball players after 11 weeks of training,” Journal of the International Society of Sports Nutrition, 2013, 10:55.

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