Many people try to lose weight by going on a diet. But this new research, funded by the National Institutes of Health, suggests that restricting certain foods for a set time period in the manner of dieting could cause withdrawal symptoms similar to those associated with drug abuse and increase cravings for those foods. This could lead periodic dieters to gorge on forbidden foods when they have the opportunity, the researchers suggest.
Their experiment involved two groups of ten rats: One was provided with ordinary chow for five days and then with tastier, sweetened chow for two days over a period of seven weeks. The other group was provided with ordinary chow alone.
They found that when they provided rats with sweetened chow and then withdrew it, they ate less ordinary chow when that was all that was available and ate far more when presented with the sweetened chow.
The researchers wrote: “Motivational processes can become perturbed in individuals who experience repeated contrasts in the intensity of hedonic stimuli over time. Adaptively, such processes may shift food-seeking and consummatory behavior toward energy-dense, high-reward foods, while devaluing efforts to obtain less energy rich, low-reward foods.”
The scientists also used a drug to suppress CRF (corticotrophin-releasing factor) – a molecule linked to the brain’s reaction to stress – which is known to play a motivational role in withdrawal symptoms to all major drugs of abuse, including alcohol, nicotine, cocaine, opiates, cannabis and amphetamines.
After the seven-week feeding period, the researchers administered the CRF-blocking drug and found that the sweet-chow group binged less. Before the drug was administered, that group had higher CRF levels when provided with ordinary chow, and normal levels when given sweetened chow.
The researchers concluded that these “addiction-like changes” caused by bingeing on sweet food may promote intake of tasty but energy-dense foods, discourage consumption of healthier alternatives, and produce negative emotional responses when tastier foods are unavailable.
Source: Proceedings of the National Academy of Sciences
www.pnas.org/cgi/doi/10.1073/pnas.0908789106
“CRF system recruitment mediates dark side of compulsive eating”
Authors: Pietro Cottone, Valentina Sabino, Marisa Roberto, Michal Bajoe, Lara Pockrosa, Jennifer B. Frihaufa, Eva M. Feketea,b,c, Luca Steardog, Kenner C. Riceh, Dimitri E. Grigoriadisi, Bruno Contic,e, George F. Kooba,b, and Eric P. Zorrilla