January 2010

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Health Capsule

Restricting Sugary Food May Backfire

Do you try to lose weight by putting certain foods off-limits? Depriving yourself of the foods you love, new research in rats suggests, might drive you to eat more of those foods later.

NIH-funded researchers recently found that rats given occasional access to sugary food ate less of their normal food even when sweet food wasn’t available. When the sweet food became available again, they overate it. In other words, the rats were holding out for the good stuff.

The researchers suspect the brain’s stress system might be behind this behavior. Withdrawal problems for drugs of abuse are driven by the brain’s fear, anxiety and stress response. Could something similar happen when you deprive yourself of certain foods?

The scientists tested a drug that blocks the action of CRF, a molecule involved in the brain’s response to stress. CRF has been tied to withdrawal for every major drug of abuse.

The team divided rats into 2 groups. One received cycles of 5 days of regular chow and 2 days of sweet chow. The other was given only regular food. All the rats could eat as much as they wanted. After 7 weeks, the rats were given the CRF-blocker.

The blocker blunted the rats’ bingeing. The diet-cycled rats ate more regular chow and then, when it was available, less of the sweet. The drug also blocked the rats’ anxious behavior when the sweet food was withdrawn. It had no effect on the rats eating only normal chow.

When eating regular chow, the diet-cycled rats had much higher CRF levels in a brain region involved in fear, anxiety and stress. CRF levels were normal, however, when they were fed the sweet food.

Human eating behavior is more complicated than rats, of course. But these findings suggest that cutting out certain foods may cause you to feel stressed until you eat those foods again. Research shows that the best way to lose weight is to change your lifestyle to eat healthier and get more physical activity.