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Don't Stop Fidgeting!

BY: Joann Bally CSCS

We all know people who seem to be able to overeat and not gain weight, while most of us must pay the price in increased weight (and fat) when we overdo it significantly. One meal isn't going have much of an effect, but extended overeating during vacations, holidays, etc. will have an effect.

So what is it with these people who don't gain easily? Consider that energy from food is expended in three ways: basal metabolic rate (energy expended when you are lying quietly), thermal effect of food (extra energy spent as a result of eating), and physical activity. One might think that the body, in an attempt to maintain the status quo weight-wise, would increase the metabolic rate, or perhaps burn off more calories in digesting the food. One would be wrong.

Researchers overfed 16 nonobese adult volunteers by 1000 calories per day for 8 weeks (reported in Science, vol. 283, pp 212-214). On average, 432 of those calories were stored (mostly as fat) and 531 were dissipated through increased energy expenditure. (The other 37 are unaccounted for.) However, fat gain varied among the volunteers from less than a pound to over 9 pounds.

What happened?

Let's look first at basal metabolic rate (BMR). BMR increased an average of 5% in response to overfeeding, accounting for only 8% of the excess ingested energy. No, it wasn't BMR. Next, let's look at thermal effect of food (TEF). TEF did increase by 14% with overfeeding, but that was pretty much just proportional to the extra food. So it wasn't TEF.

Physical activity in this study was divided into volitional exercise (sports and fitness related activities) and nonexercise activity thermogenesis (NEAT). NEAT was further described as movements such as activities of daily living, fidgeting, spontaneous muscle contraction, and maintaining posture. Volitional exercise, as part of the study design, was maintained at the same low level throughout the study. So it seems, by process of elimination, that the difference that determined how much a volunteer would gain was a difference in NEAT. This means that some people respond to overeating by increasing movement, overfidgeting, perhaps. Others do not and end up gaining more weight--an efficiency that is beneficial in times of famine, but not in times of plenty. The tendency to increase spontaneous activity is thought to be genetic, although the mechanism is yet to be discovered.

The researchers speculate that encouraging NEAT activation, perhaps through behavioral strategies, may eventually be useful in combating obesity. But we could start doing that now, couldn't we?

Here's something to think about. Would you have volunteered for this study?