Are you one of the many people who use working out as an excuse to eat whatever you want? A recent research study suggests you might want to rethink your strategy. In an article published in Medicine & Science in Sports & Exercise, researchers studied the effects of a high fat diet and exercise on the progression of coronary artery disease (CAD) in pigs. Coronary artery disease is a condition in which the tiny arteries that bring blood, and therefore oxygen, to your heart muscle begin to narrow. When your arteries narrow, your heart muscle can’t always get enough oxygen. If this becomes severe enough, the heart muscle begins to die from the lack of oxygen. This is a common cause of chest pain, or angina, and can affect how well your heart works.
In this study, the researchers broke the pigs down into four groups. The groups were broken down as follows:
1. 8 pigs ate a high-fat diet and did not exercise
2. 8 pigs ate a high-fat diet and did exercise
3. 8 pigs ate a normo-fat diet and did not exercise
4. 8 pigs ate a normo-fat diet and did exercise
The pigs that did exercise ran on a treadmill for 85 minutes/day, 5 days/week. The normo-fat diet consisted of 8% of total calories coming from fat, while the high-fat diet consisted of 46% of total calories coming from fat. After 24 weeks, specific regions of the coronary arteries were examined. Researchers found (somewhat surprisingly) that the pigs eating the high-fat diet all showed progression of CAD at the cellular level within their coronary arteries, regardless of whether they exercised or not. Exercise did not act as a protective mechanism. The pigs eating the normo-fat diet did not show such significant progression.
There are a few things I took away from this study. One is the realization that this study examines one VERY SPECIFIC potential benefit of exercise. The researchers discuss some potential explanations for why exercise did not alter the progression of the disease. One reason suggested is that the benefits of exercise were seen in other areas of the heart and coronary arteries (they looked at a small, specific section of the right coronary artery, left anterior descending artery, and the left ventricle) that they did not see because of where they chose to sample. While this is unlikely, it is possible. More likely explanations include the possibility that exercise is beneficial in more advanced stages of CAD (the pigs were only in the early stages), or that exercise has positive benefits on things this study did not look at. That could include better homeostasis (better blood pressure, heart rate, hormonal control, etc) or improvements in other parts of the vasculature (blood vessels).
Also, it is important to keep in mind that the pigs in the study did exercise, however there were absolutely no changes to their diet. Perhaps there would have been significantly better effects if there had been even small changes to their diet in conjunction with the physical activity.
The main point I walked away with, however, and the reason I am posting this for knowledge sharing and discussion, is to drive home the point that exercise alone is not enough! Exercise is wonderful for you. It has countless benefits, both physically and mentally. But it is not realistic to think that you can eat whatever you want, and then just “sweat it out”. Please be aware of how you are choosing to fuel your body.
What do you all think of the findings? I realize you have limited information on the research design, and if you would like me to send you the full article, just let me know! I cannot post it publicly on this website because I purchase the subscription to this journal, and am sure there are copyright laws or something 🙂 Has anyone tried to lower blood pressure, cholesterol, blood sugar or weight with just exercise and found it was not enough? Did you have to change your diet as well?
Here is the citation for the article:
Arce-Esquivel, A., Kreutzer, K., Rush, J., Turk, J. & Laughlin, H. (2012). Exercise Does Not Attenuate Early CAD Progression in a Pig Model. Medicine & Science in Sports & Exercise, 44(1), 27-38.