Intermittent Fasting: Effects on Hunger and Weight Gain

MedicalResearch Interview with:
Alicia J. Kowaltowski, MD, PhD
Professor of Biochemistry Departamento de Bioquímica, IQ,
Universidade de São Paulo
São Paulo, SP, Brazil

MedicalResearch: What are the main findings of the study?

Dr. Kowaltowski: Intermittent fasting (24 hour cycles of all-you-can-eat followed by 24 fasting) is often used as a way to control excessive weight gain in laboratory animals, despite the fact that these animals overeat on the days they get food, and end up ingesting total quantities of food very similar to animals that eat every day. We show here that although lower weight gain occurs with intermittent fasting and there are some health benefits in adopting this diet, there are also some undesirable consequences. One such consequence is that this diet changes the control of hunger in the hypothalamus within the brain, making the rats hungry all the time, even when they are eating.

MedicalResearch: Were any of the findings unexpected?

Dr. Kowaltowski: Most of the findings were unexpected. When we began this project, our hypothesis to explain the lower weight in intermittently fasted animals was that their mitochondria were less efficient. Careful mitochondrial studies showed this was not the case, and we had to look for changes in how the brain controls metabolism in order to explain how the diet promotes the changes we see. At this point we sought collaboration with Prof. Licio Velloso (from the University of Campinas), who was invaluable in this study.

MedicalResearch: What should clinicians and patients take away from your report?

Dr. Kowaltowski: This is a basic science study, involving a rodent model, so extrapolations to humans would be premature at this point. However, I think it does show that not all dietary interventions that lead to weight loss are necessarily “good” for all aspects of our health.

MedicalResearch: What recommendations do you have for future research as a result of this study?

Dr. Kowaltowski: Although we have demonstrated that intermittent fasting changes the hunger control centers in our brain, we still don´t understand the mechanism. We need to understand how this happens at the molecular level if we want to interfere in this process in the future.


Intermittent Fasting Induces Hypothalamic Modifications Resulting in Low Feeding Efficiency, Low Body Mass and Overeating. Chausse B, Solon C, Caldeira da Silva CC, Masselli Dos Reis IG, Manchado-Gobatto FB, Gobatto CA, Velloso LA, Kowaltowski AJ. Endocrinology. 2014 May 5:en20132057. [Epub ahead of print]


Last Updated on May 12, 2014 by Marie Benz MD FAAD