HUNGER ON THE BRAIN

Dieting makes brain cells eat themselves, and cause more hunger.

When you diet, you are likely to lose not only unwanted fat cells but also muscle mass that has been painstakingly built up: the body breaks it down in order to get energy. And this breakdown has more far-reaching consequences than hitherto believed.

ln an experiment with mice, Rajat Singh and his colleagues at the Albert Einstein College of Medicine in New York have proven that the process of autophagy (literally, 'self-eating') does not stop even at brain cells.

The doctors first let the rodents starve for 12 hours. As a consequence, some neurons in the brain's hypothalamus, the switch centre for vegetative body functions, began to 'eat' bits of themselves. Surprisingly, even proteins that stimulate and regulate appetite in the diencephalon fell victim to this brain cell cannibalism.

The researchers say this process gives rise to a vicious circle: when the body starves, it triggers autophagy. Subsequently, the brain begins to transmit increased and uncontrolled hunger signals. This escalation could be the reason why it is 50 difficult to maintain diets.

However, the results of another test hold out hope. ln a separate experiment, the research team was able to use an inhibitor to block the self-cannibalism of brain cells. lhis in turn minimised the hunger signals and the mice became slimmer after the fasting programme.

Scientists are optimistic that this method will apply to humans as well.

Extract from "Geo English Edition", n.48, May, 2012, p. 23. Adapted and illustrated to be posted by Leopoldo Costa.