The American diet is frequently blamed for the poor health of Americans and, increasingly, other countries. The quest for the healthiest way to eat can literally take people around the world to find the right foods eat.


Unfortunately, diets and supplements that include these “super foods” are rarely the answer to good health on their own. It turns out that the key getting the optimal health benefits from your diet isn’t the food itself – it’s exercise!


For decades scientists have tried to isolate the types of foods or individual nutrients that lead to good health by studying what healthy and unhealthy people eat around the world. In some studies eating more of a certain nutrient or food, like saturated fat or red meat, was associated with a higher risk of heart disease and people who ate more fish had better heart health.


This is how we arrived at the common guidelines that encourage us to eat more fish and less red meat. The assumption was that the saturated fat in red meat was the cause of more heart attacks in Americans while the beneficial oils in fish protected the Japanese from heart disease.


But these studies, or at least the interpretation of these studies, didn’t take into account the fact that the populations that had the higher heart attack risk were also less active than their healthier counterparts. Perhaps it was the physical activity that made the difference in health.


A good example of this is the popular Mediterranean diet, which is often touted as the healthiest diet in the world. It’s true that people in the Mediterranean region historically tended to have a lower risk of heart disease. This was thought to be due to their diet which emphasizes healthy fats from olive oil along with vegetables, whole grains, seafood instead of red meat, and red wine in moderation.


Unfortunately, eating more olive oil or drinking more red wine, both recommendations based on the Mediterranean diet, won’t necessarily make you any healthier. This is because health benefits are due to a complex interaction of what we eat and other lifestyle factors, including activity. And people in the Mediterranean region move a lot more than we do, a key to realizing the benefits of the local diet.


Another example is the Ornish diet, a low-fat, semivegetarian diet that has been credited with improving blood lipids and even reversing the process that clogs arteries in heart disease. This is part of the reason for the recommendation to avoid foods high in saturated fat and cholesterol and eat more vegetables.


It’s true that this diet has been shown to improve heart health, but the subjects in the studies also exercised regularly. Achieving the full benefits of this diet requires exercise, too.


Even the typical American diet won’t necessarily be unhealthy when combined with enough exercise. The Olympic swimmer Michael Phelps famously revealed what he ate on a typically day.


The amount and type of foods he consumed were not what you would expect from someone so fit and healthy! Without the hours of training he engaged in each day that diet would almost certainly have resulted in obesity and poor health.


So, as you work toward improving your diet, don’t forget about the importance of daily exercise or other activity in maximizing the health benefits. And when people ask your secret, you can tell them that the real key to a healthy diet is exercise.


Brian Parr, Ph.D., is an associate professor in the Department of Exercise and Sports Science at USC Aiken where he teaches courses in exercise physiology, nutrition and health behavior.