Studies have shown that dieting does have an effect on psychological wellbeing. Famous early studies in the 20th century on men who were deprived of food for periods of months on low-calorie regimes did find that they became more fixated on food for example. Professor Peter Rogers from the University of Bristol is an expert in food and behaviour. He says that people who lose weight, just to regain it all, are opening themselves up to periods of elation followed by disappointment and dejection. ‘There are a lot of unrealistic expectations. It takes much longer than people think to reduce weight safely and maintain it. Of course, there are lots of individual variations, but yo-yo dieting may affect self-esteem.
People can and do feel irritable when their blood sugar levels start to drop, (a phenomenon known as hanger or ‘hunger anger’) since the brain is dependent on glucose to do its job, but Professor Rogers is sceptical about the link between dieting and levels of the feel-good hormone serotonin in the brain. ‘The link is unclear and we don’t really know if dieting leads to neurochemical changes which affect mood.’