Saturday, October 24, 2009

Phun Physiology: Regular Exercise May Prevent Weight Regain after Long-Term Weight Loss

With the demanding portion of the cycling season pretty much in the rear-view mirror, we now head into the offseason. I seem to grow in girth just relishing the thought of the upcoming holidays! Some cyclists, myself included, intended to and ultimately succeeded in shedding a few pounds during the cycling season. But don’t we ultimately share the same fate as dieters who successfully lose weight only to regain it again?

We know that for many individuals weight-loss diets sooner or later fail. In fact, not only do most dieters regain all of the weight they lose while dieting but are dismayed at how quickly they regain the weight. The “yo-yo” phenomenon in fact has a physiological basis.

Dieting triggers numerous physiological changes aimed at efficient weight regain as if the body seeks to reestablish its pre-diet “steady state.” Weight loss causes a decrease in hormone levels of leptin and insulin. The brain perceives an energy store deficit and signals us to eat. Ironically, weight loss actually triggers the production of additional fat cells, which facilitate rapid weight regain, should we overeat just once. And when we overeat, we feel less like exercising, which is the very antidote for preventing weight regain.

But it may be possible to turn the body’s physiology in the opposite direction so that we can benefit long term from a successful weight loss program, according to experts. This is the claim made by a team of researchers in an article published just this summer in the American Journal of Physiology entitled, “Regular exercise attenuates the metabolic drive to regain weight after long-term weight loss.” This topic might be of interest to cyclists heading into the off-season.

But haven’t we known for some time that most successful weight maintenance programs include exercise? True, but now it seems that the science (i.e., underlying physiological mechanisms) may be getting closer to this observation, giving us a reason and also the motivation to stay on track.

Of note, the researchers contend:

The novel observations from this study are that regular, aerobic, treadmill exercise in male rats countered several metabolic adaptations to weight loss that are known to facilitate weight regain and the eventual relapse to obesity.
One physiological change brought about by regular exercise after a period of successful weight loss is the body’s utilization of fat as an initial energy source rather than carbohydrate.

There is more good news. So far as it might apply to humans, the regular exercise required to keep weight regain in check is not only of low intensity but low duration calculated at four percent of daily energy expenditure, or thirty minutes of fast walking, for example.

What does this mean for cyclists? Think about the added benefit of base training this winter, consisting of long slow distances (the cyclist’s LSD). One benefit is weight maintenance. As an increased, albeit negative, incentive, recall that weight gain automatically lowers VO2max, since the calculation of the latter includes dividing by one’s body weight.

Consequently, to retain many of the physiological gains posted during the year, some cyclists may want to consider at least regular doses of low-intensity exercise with the approaching holiday season. See you out there!

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