Exercise, Then Starve? Not Necessary

Feb. 3, 2010 — -- Even a very small change in diet in the hours after vigorous exercise can have a significant impact on how the human body metabolizes food, according to new research by a team of scientists seeking to understand exactly how the body processes vital resources, like sugar.

The focus of the research, published in the current issue of the Journal of Applied Physiology, is on diabetics, so the findings could have profound implications for persons with insulin resistance, but the research also sheds some light on the symbiotic relationship between eating and exercising.

The study suggests, for example, that it isn't necessary to starve yourself after working out in order to reap the full benefits of exercise. You probably can replace those calories that you burned off on the treadmill and profit just as much as the fanatics who go hungry, at least when it comes to processing the day's supply of sugar.

Nine "healthy young men" participated in a grueling research project so scientists could measure exactly how they benefited from exercise and diet.

It's been known for years, of course, that exercise helps in many ways, but it's less clear how what we eat helps, or hinders, the final results. That is one of the goals of this research, which is still in its early stages at the University of Michigan.

The participants, who lived at a hospital during the research so their activities and diet could be strictly controlled, all benefited from a reduced carbohydrate diet in the hours after exercising.

Specifically, their insulin sensitivity was enhanced, making it easier for their bodies to take up sugar from the blood stream and concentrate it in tissues like muscles, where it can be stored or used as fuel.

All these guys were healthy subjects, in their late twenties, and none of them were obese or diabetic, making the results all the more impressive.

"If you see a little bit of an increase (in insulin sensitivity) in a healthy person, you are going to see a profound result in an obese person," Jeffrey Horowitz, the study's senior author, said in a telephone interview. Horowitz and his colleagues have just started testing obese persons.