Yo-Yo Dieting May Work Like Addiction in the Brain

If you’ve fallen victim to yo−yo dieting in the past, it may be because the underlying brain mechanisms are similar to those involved in drug and alcohol addiction. A new study in Proceedings of the National Academy of the Sciences found that rats had similar withdrawal effects whether they were coming off food or drugs.

Lead author Pietro Cottone and his team at Boston University’s School of Medicine fed rats a normal diet for five days and then offered them a high−sugar, chocolate−flavored food for two days. When the researchers switched the rats back to their regular diet, the rats were not happy: their anxiety levels increased and they behaved as if they were in withdrawal from drugs or alcohol. Sometimes the rats actually refused to eat the food which had been perfectly acceptable previously.

When Cottone and his team suppressed this system by blocking the hormone’s receptor, the food withdrawal response disappeared.

Cottone explains that, in rats and humans alike, “[a] history of dieting and relapse generates anxiety. The next attempt to avoid junk foods is going to be more painful and stressful than the previous one, and therefore the likelihood of relapse is going to be progressively higher and higher.”

What’s going on the brain to explain these phenomena? The researchers found that during the rats’ withdrawal response, there was increased gene expression of the stress hormone corticotropin−releasing factor (CRF) in the amygdala, an area of the brain largely involved in emotions (including fear and stress). When Cottone and his team suppressed this system by blocking the hormone’s receptor, the food withdrawal response disappeared.

Cottone also explains the yo−yo dieting phenomenon in light of evolution: “We evolved over millions of years to defend ourselves against scarcity, and palatability helped us during this long process,” he says. “But now there is an abundance of palatable food. We don’t have to fight or expend much energy to find food. It’s easy. Palatability is now working against us.”

Whether the research will lead to new treatment methods for food addiction is somewhat unclear, but the researchers are optimistic. “We think we have found a new way,” Cottone says, “a new hope we can work on.”