It is easier for women to gain weight than men because part of the brain is “wired differently” in males and females, a study has found.
The discovery could change the way obesity is tackled through targeted medication, experts at the University of Aberdeen believe. Working with teams from the universities of Cambridge and Michigan, they used a mouse model to study the sex difference in weight gain driven by differences in physical activity and energy expenditure.
During the study, researchers were able to transform obese male mice with increased appetite and reduced physical activity into lean, healthy mice, but the same transformation did not occur in the female mice.
The project was led by Professor Lora Heisler from the Rowett Institute of Nutrition and Health at the University of Aberdeen.
She said: “The World Health Organisation reports higher rates of obesity in women worldwide, reaching twice the prevalence of men in some parts of the world. Currently there is no difference in how obesity is treated in men and women. However, what we have discovered is that the part of the brain that has a significant influence on how we use the calories that we eat is wired differently in males and females.
“Cells in this brain region make important brain hormones called pro-opiomelanocortin (POMC) peptides that are responsible for regulating our appetite, physical activity, energy expenditure and body weight.
“What we have discovered is that not every POMC neuron performs the same function.
“While the subset targeted by obesity medication lorcaserin influences appetite in both males and female mice, in males, this subset has the added benefit of also modulating physical activity and energy expenditure.
“In female mice, this source of POMC peptides does not strongly modulate physical activity or energy expenditure. So, while medications targeting this source of POMC peptides may effectively reduce appetite in females, they will not tap into the signals in our brain that modulate physical activity and energy.”
The research, published in the journal Molecular Metabolism, could lead to the development of new sex-specific medications.