Interval Training for fat loss

The benefits of interval training over low-intensity (e.g. walking) and moderate-intensity (e.g. jogging) exercise are many. Not only do individuals who perform interval training get more fat loss, but they also see greater improvements in endurance and heart function. But since this discussion is about the effect of interval training on fat loss, I'll leave the discussion of the latter two for a later date.

In this first study three groups of women were assigned to do either interval training, steady-state training, or nothing for 15 weeks. After the 15 weeks, only the interval training group seen reductions in total body mass, fat mass, truck fat, and fasting insulin levels. The latter result, an improvement in fasting insulin levels, is why I believe interval training and carbohydrate reduction work for the same reason, both improve insulin sensitivity. Insulin is a fat storage hormone, and the less sensitive you are, the more insulin your body secretes.

From the conclusion:

HIIE (high intensity intermittent exercise) three times per week for 15 weeks compared to the same frequency of SSE (steady-state exercise) exercise was associated with significant reductions in total body fat, subcutaneous leg and trunk fat, and insulin resistance in young women.

If you delve further into the PhD thesis this study is based on you get some startling results. For example, the SSE group actually had an smallincrease in fat mass from 31.69% to 32.28%. One individual actually gained 7% body while participating in the SSE. This is a pretty typical result with SSE. Compare this to the HIIE group who lost about a little over 3% body fat. If you look at the differences in regional fat distribution, for example in the trunk, the HIIE lost 10% of their trunk (midsection) fat mass but the SSE gained 11%! The author theorized that this was the result of the HIIE protocol releasing catecholamines which stimulate fat burning, particularly in the abdomen in which the fat is especially sensitive to the effects of the catecholamines.

Another interesting factor to note is that the researchers found the individuals that didn't respond well to the HIIE protocol were insulin resistant, and since insulin inhibits the mobilization of fat this could account for their lack of results. This suggests that if your exercise is competing against your diet for improving insulin sensitivity that your diet will win out and you'll be unable to reap the benefits of interval training.

So, this is but one example of the studies that show interval training to be superior to traditional cardio routines. It's a very good one because of it long duration and the fact that the researchers gathered much data. Next time I talk about intervals, I'll get into some of the other health benefits that have greater improvement from them.