Yoyo Dieting Leads to Drug Withdrawal-Like Stress Response

Researchers at the Pearson Center for Addiction and Alcoholism Research and the Scripps Research Institute say that yoyo dieting can cause changes in the brain that are likely to induce weight gain.

The researchers knew that positive reinforcement can help people continue with weight loss. For example, when you can suddenly fit into previously tight clothes you may gain the motivation to continue your weight loss efforts. They wanted to know whether negative reinforcement, for example - dieting makes you feel bad so you eat more to feel better again, may play a role in those that fail to lose weight.

In an animal model experiment, rats were given periodic access to sweet and or fatty foods and then healthy but less tasty foods – in alternating cycles of 5 days of healthy food followed by 2 days of fatty/sweet foods. The rats were allowed to eat as much as they wanted. 

The Results

• These rats started to eat less of the healthy foods and on days when only healthy foods were available, these rats avoided all stressful situations

• When the fatty/sweet foods were made available, the rats could once again face stressful situations, but they ate far more than they needed to

When the researchers looked at what was happening at the neural level, they found:

• During healthy food days, the yoyo dieting rats had 5 times the normal amount of a stress peptide in the brain that regulates fear, anxiety and stress

• During days when the rats were allowed to eat fatty/sweet foods, levels of this peptide returned to normal

During healthy food says, the rats were in a literal state of withdrawal, very similar to a drug addiction withdrawal.

Alternating between dieting and bingeing leads to elevated feelings of stress during periods of healthy eating, and since this stress is relieved by binge eating, people are very likely to eat to feel better, and thus fail to lose weight – or even gain weight.

Senior author Eric Zorilla sums up the withdrawal-like consequences of yoyo dieting by saying, "Our findings suggest that intermittently eating sweet food changes the brain's stress system so that you might feel stressed, even though nothing that terrible has happened. In other words, you might be self-medicating stress-like symptoms of abstinence with that piece of pie.