Dr Terence Gerace and Dr Valerie George of the department of epidemiology and public health at the University of Miami studied 438 male firefighters aged between 20 and 58 over a period of eight years. The men filled out a detailed questionnaire about their lifestyle and eating habits in 1984, and were weighed then and in 1991. The study, published in the journal Preventive Medicine, enabled scientists for the first time to identify behaviour that has the greatest influence on changes in weight.
Surprisingly, physical inactivity was not the greatest predictor of weight gain. Twenty-six per cent of the firefighters gained 15lb or more in eight years; 42 per cent gained more than 10lb; and 65 per cent gained more than 5lb.
Unmarried firefighters gained an average of 11.7lb over the eight years, far more than married or cohabiting staff. This finding echoes an earlier study of women which revealed that a higher than expected number of unmarried women put on weight over six years. Could comfort eating as a way of dealing with social isolation be the crucial emotional factor that explains the gain?
There may be several factors. The firefighters' wives might prepare low-calorie meals. They might encourage weight control plans, including exercise. It could be that having a partner who is critical, or at least aware, of your body shape and size could be much more helpful in preventing weight gain than previously realised. Perhaps also, argue Gerace and George, single firefighters eat out more often, eat larger unshared portions, and eat more frequently due to boredom.
But one of the most significant findings is that the firefighters who reported eating "faster" gained the most weight. Could school dinners, with their emphasis on getting children to eat quickly, have a longer-term detrimental effect on weight and lifestyle by inculcating the wrong attitude to food? Perhaps Jamie Oliver should not just be looking at what our children eat, but how they eat it.
Dr Raj Persaud is Gresham professor for public understanding of psychiatry, and director of the Centre for Public Engagement, King's College London.
His latest book is The Motivated Mind (Bantam Press). Email: firstname.lastname@example.org