MedicalResearch.com Interview with:
Giuseppe Pugliese, MD, PhD
for the Italian Diabetes and Exercise Study 2 (IDES_2) Investigators
Department of Clinical and Molecular Medicine
‘‘La Sapienza’’ University
Diabetes Unit, Sant’Andrea University Hospital
Rome, Italy
MedicalResearch.com: What is the background for this study?
Response: There is a growing epidemic of obesity and type 2 diabetes worldwide,
which are causally related to the increasing prevalence of “physical
inactivity”, i.e., an insufficient amount of moderate-to-vigorous
physical activity according to current guidelines, and
“sedentariness”, i.e., too many hours, especially if uninterrupted,
spent in a sitting or reclined position. These two unhealthy
behaviors exert their detrimental effects independently of each other
and are very common among people suffering from type 2 diabetes, who
would therefore benefit from increasing physical activity and reducing
sedentary time, as recommended by current guidelines.
However, such a behavior change is generally difficult for a number of
internal and external barriers and requires behavioral interventions
targeting both physical activity and sedentary habits. Unfortunately,
there is no definitive evidence that this is indeed feasible and,
particularly, that, if adopted, change in behavior can be maintained
in the long term.
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MedicalResearch.com Interview with:
Dr. Agatha van der Klaauw, PhD
Wellcome Trust Postdoctoral Clinical Fellow
Wellcome Trust-MRC Institute of Metabolic Science
University of Cambridge Metabolic Research Laboratories
Addenbrooke's Hospital
Cambridge, United Kingdom
Medical Research: What are the main findings of the study?
Dr. van der Klaauw: Obesity occurs when we eat more calories than we burn which is often easy to do as many foods are highly palatable and high in calories. Highly palatable foods such as chocolate trigger signals in the brain that give a feeling of pleasure and reward (sometimes called cravings) which can contribute to overeating. These signals are processed in the reward centres in the brain, where sets of neurons release chemicals such as dopamine. However, very little is known about whether the reward centres of the brain work differently in some people who are overweight.
In this study, we were interested in studying overweight people who had a problem with the melanocortin 4 receptor (MC4R) gene. About 1% of obese people have a problem in this gene which contributes to weight gain from a young age. We compared three groups of people: people who were overweight due to a problem in the MC4R gene, people who were overweight but the gene was normal and some people who were normal weight. We performed functional Magnetic Resonance Imaging (fMRI) scans to look at how the reward centres in the brain were activated by pictures of appetizing food such as chocolate cake compared to bland food such as rice or broccoli and non-food items such as staplers.
We found that in normal weight people, the reward centres are activated (light up) when they are shown pictures of cake or chocolate and the same was seen in overweight people with a problem in the MC4R gene. But we found that the reward centres were underactive in overweight volunteers (in whom the gene was normal).
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