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February 28, 2011

Fat Cell Mania

We’re now two months into the New Year–the approximate amount of time where most people abandon their resolutions to lose weight and get in shape. It’s the classic “yo-yo” effect. Dieters generally begin their quest highly motivated to lose weight, but soon thereafter are back to their old habits. At some point they’ll try another diet only to again regress. And hence the cycle continues…

There is a bigger problem with such behavior than merely the short-term weight regain. Namely, yo-yo dieting ultimately can result in “resetting” a person’s “set point” and thus make it increasingly harder to lose weight in the future. The reasons behind the yo-yo effect have been somewhat hazy, but new research may help to shed some light on the issue. First a little background info. There are two mechanisms by which you gain fat. The first is called fat cell hypertrophy. Simply stated, this means that your fat cells (i.e. adipocytes) grow larger, which is the primary means for your body to store additional fat. Once adipocytes reach a certain size, however, they undergo a process called hyperplasia. This involves a “splitting” of adipocytes so that more fat cells are available for storage. Your body can create an endless supply of new fat cells, allowing for a virtually unlimited amount of body fat storage.

With this in mind, let’s look at the study in question. Researchers from Yale University studied the Regional differences in cellular mechanisms of adipose tissue gain with overfeeding to help determine the cellular mechanisms that regulate fat accumulation. In short, 28 men and women were overfed for 8 weeks. Consistent with the First Law of Thermodynamics, they gained weight from this regimen. No surprise here. The interesting aspect of the study, though, was that in addition to an increase in size of adipocytes, the number of fat cells significantly increased, too. What’s more, the hyperplasia was regional specific, with the lower body adding more fat cells than the upper body.

What does this all mean? Simply that overeating leads to an increased number of fat cells, which makes it more difficult to lose weight in the future. Even short-term periods of overfeeding (in this case as little as 8 weeks!) was enough to result in fat cell hyperplasia. While fat cells can be “deleted” (via a phenomenon called apoptosis), it is a more complex process than reducing the size of fat cells.

Bottom line: Avoid yo-yo dieting at all costs. If you fall off the dietary wagon, get back on as quickly as possible. A few days of food bingeing won’t have a tangible effect on your physique; a couple of months surely will.

Stay Fit!

Brad

Tchoukalova YD, Votruba SB, Tchkonia T, Giorgadze N, Kirkland JL, Jensen MD. Regional differences in cellular mechanisms of adipose tissue gain with overfeeding. Proc Natl Acad Sci U S A. 2010 Oct 19;107(42):18226-31