Have you ever heard the line “I have to go burn off that (insert “bad” food here) I just ate”? Have you ever said that yourself? Despite my previous belief that there was nothing to support the possibility of this idea being useful, I have found proof that there may be some merit to this guilt-laden statement!
Not to get knee deep in the socio-cultural ideas surrounding certain foods being labeled “good” or “bad” without proper knowledge of nutrition and influence of strong lobbying groups on government policy, I want to present the idea that well timed bouts of exercise may help minimize that fat depositing effects of some foods. The first place I came across this idea was in The 4-Hour Body, by Tim Ferriss. In his various experiments with body transformation/recomposition, Mr. Ferriss found research suggesting that muscular contraction (via exercise) led to GLUT4 (a glucose transport molecule) moving from inside the cellular membrane to outside of the cellular membrane where it would then pull glucose into muscle cells (if you would like to look at some research that shows this click here or here).
Why does the movement of GLUT4 even matter? The fascinating thing about GLUT4 is that it is also moved outside of the cell membrane by insulin in response to elevated levels of glucose in the blood. Insulin’s job is to tell fat, muscle, and liver cells to move GLUT4 to the outside of the cell membrane to transport glucose inside of the aforementioned cells. These two methods of getting GLUT4 to the outside of the cell membrane are independent of one another but can occur at the same time. The big deal here, as Tim Ferriss has had success with, is that if we are trying to reduce body fat percentage we would rather have glucose enter muscle cells where it can be burned instead of being allowed in to fat cells where it will sit (and hide that wonderful six pack you have been diligently developing!). To get the muscle cells to take up glucose before insulin levels rise after a high carbohydrate meal and tell fat cells and liver cells to start grabbing glucose muscular contraction is needed BEFORE insulin can signal the other cells as well as WHILE the other cells are being signaled. This is an amazing insight in to the timing of physiological processes as insulin will appear in the blood after glucose appears in the blood but muscular contraction can occur at any time to activate GLUT4 in muscle cells so that we can try to beat insulin to the punch and preferentially load glucose in to muscle. The way Mr. Ferriss uses this idea is to perform light exercises (often air-squats or wall push-ups) for about 60-90 seconds before he eats a “bad” meal and again approximately 90 minutes after his “bad” meal to get GLUT4 activated on muscles at the time when insulin is likely the highest and getting fat and liver cells ready to start taking up glucose.
To (hopefully) make this insight a little more clear, if insulin signaling of GLUT4 is the primary method of transporting glucose out of the blood it will end up wherever it can go and, when trying to decrease body fat percentage, this is not a good thing as glucose will end up in fat cells and make them fatter. If GLUT4 is activated in muscle tissue before and after meals (this does not involve complicated exercise routines…just about 90 seconds of squatting and wall push-ups should do the trick) then more glucose will likely be taken up by muscle cells (where it will be stored as glycogen or burned as energy immediately) and less of it will end up in fat cells. This may be a useful technique for minimizing the effects of a “bad” meal but not necessarily a cure-all for a diet that is heavy in foods that are not nutritionally beneficial to the optimal function of our physiology. Use this information as a temporary fix to minimize the effects of indulgent eating (just be prepared to find creative places to perform the exercises as you might be made fun of by onlookers and friends if you start doing squats in the middle of an ice cream parlor or wall push-ups in a greasy spoon).