Even before obesity occurs, eating fatty and sugary foods causes chemical changes in the brain, meaning that going on a diet might feel similar to going through drug withdrawal, according to a study published today by Dr. Stephanie Fulton of the University of Montreal's Faculty of Medicine and its affiliated CRCHUM Hospital Research Centre. "By working with mice, whose brains are in many ways comparable to our own, we discovered that the neurochemistry of the animals who had been fed a high fat, sugary diet were different from those who had been fed a healthy diet," Fulton explained. "The chemicals changed by the diet are associated with depression. A change of diet then causes withdrawal symptoms and a greater sensitivity to stressful situations, launching a vicious cycle of poor eating."
The research team feed one group of mice a low-fat diet and a high fat diet to a second group over six weeks, monitoring how the different food affected the way the animals behave. Fat represented 11% of the calories in the low-fat diet and 58% in the high-fat diet, causing the waist size in the latter group to increase by 11% - not yet obese. Next, Fulton and her colleagues use a variety of scientifically validated techniques to evaluate the relationship between rewarding mice with food and their resulting behaviour and emotions. They also actually looked at the brains of the mice to see how they had changed.