Mice fed on a high fat or chocolate-based diet show abnormal feeding behaviours such as snacking, bingeing and disrupted eating patterns, according to new research from scientists at the Centre for Genomic Regulation (CRG) and the Pompeu Fabra University (UPF) in Barcelona, Spain. The findings of two studies published back-to-back in the journal Addiction Biology help to explain the behavioural triggers leading to obesity and point towards new ideas for preventing weight gain.
Obesity is a growing issue in many countries, accelerated by easy access to calorie-dense foods that are pleasurable to eat (known as an ‘obesogenic environment’). But while it’s clear that eating too much leads to weight gain, little is known about the underlying behaviours that lead to overeating.
To mimic this obesogenic environment, the teams led by Mara Dierssen at CRG and Rafael Maldonado at UPF offered mice the option of a high-fat ‘cafeteria’ diet or a mixture of chopped-up commercial chocolate bars alongside their regular lab chow, before carrying out a detailed analysis of the animals’ activity and feeding behaviour. Their results have been published in two back-to-back articles in the journal Addiction Biology.
Working together with Cedric Notredame (CRG) and Elena Martín-García (UPF), the scientists found that as well as becoming obese, the mice started very early to show the signs of addiction-like behaviour and binge-eating in response to these enticing foods.
For example, when offered chocolate for just one hour per day, the animals will compulsively ‘binge’, consuming as much chocolate in one hour as they would over a whole day if it was continually available. They also showed inflexible behaviours, similar to those seen in addiction, choosing to wait for chocolate while ignoring freely available standard chow. Yet, at the same time, the chocolate did not seem to satiate hunger as well as regular food.
The team found that animals on the high fat or chocolate diet also changed their daily routines. They were more likely to eat during the daytime – mice are usually nocturnal and feed at night – and they ate shorter more frequent ‘snacks’ rather than larger, longer-spaced meals.
A major problem in treating obesity is the high rate of relapse to abnormal food-taking habits after maintaining an energy balanced diet. The scientists evaluated this relapse and found that extended access to hypercaloric diets impairs the control of food seeking behaviour and has deleterious effects on learning, motivation and behavioural flexibility.
More information on the CRG website