The Hungry Brain: Outsmarting the Instincts That Make Us Overeat

by Stephan Guyenet

Yet when Levin’s team made the rats switch diets, they found that the rats seemed to defend dramatically different body weights depending on which diet they were currently eating. For example, when they were switched from Ensure to ordinary pellets, their food intake dropped impressively and they rapidly lost weight, until they approximated the weight of animals that had been eating pellets the whole time. When these same animals were switched back to Ensure, they gorged and quickly bounced back up to the weight of animals that had been eating Ensure the whole time. Again, it seemed as if the diets were not just passively causing weight gain but actually changing the set point of the lipostat. Levin ascribed much of this effect to the diet’s palatability, in part because the rats would only overeat and gain weight on chocolate-flavored Ensure—not vanilla or strawberry!