The enzyme that frustrates your weight loss efforts

You've been attempting to eat smaller portions and cut down on some foods entirely, but you're still not losing as much weight as you'd like. Well, a new study says that the complex action of one enzyme may be at the core of the problem.

Why do our bodies sometimes appear to turn against us, even as we do our best to stay in shape?
While we may adhere to a better diet and stop indulging in unhealthful foods, some of us will fin
d it difficult to lose the excess weight that troubles us.

The reason behind why our bodies store fatty tissue in the first place is quite straightforward and even intuitive, given the nature of human evolution, explains Dr. Alan Saltiel, from the University of California, San Diego School of Medicine in La Jolla.

We derive energy by burning fat tissue, but sometimes, our bodies deem it necessary to curtail how much fat we burn so that we have enough "fuel" in store for later, when we may have more urgent need of it.

"Human bodies are very efficient at storing energy by repressing energy expenditure to conserve it for later when you need it," Dr. Saltiel notes, adding, "This is nature's way of ensuring that you survive if a famine comes."

Some of the mechanisms at play in this "fuel" storage and energy consumption system are unclear, however — particularly those related to the accumulation of excess fat that leads to obesity. The question is, what pushes the "on/off" button of fat metabolism, and when?