A new study has found that younger women may lose half as much body fat as men who are on an equivalent diet.
In a newly published report, scientists used a combination of trials on rats and obese humans to determine how much of an impact age and sex have on dieting.
They found that men lose weight more easily than women early on, but after age 45 both appear to lose weight at the same rate.
The research was carried out by Scottish Scientists at Glasgow, Edinburgh and Aberdeen Universities as well as researchers at the National Center for Global Health and Medicine, Japan. The study was backed by charity group the British Heart Foundation (BHF) and published in the journal eLife.
Dr William Cawthorn, Senior Lecturer at the University of Edinburgh BHF Centre for Cardiovascular Science, who led the study, said: "Reduced-calorie diets have many health benefits and may promote healthy ageing.
"Some previous research suggested that the effectiveness of these diets may differ between males and females, but our study is the first to show that these sex differences largely disappear when dieting begins at older ages."
They compared 96 mice whose daily calorie consumption was 30 per cent less than normal and 85 mice on a normal diet over a six-week study.
After finding that the young male mice appeared to lose weight more quickly, they carried out a small human weight loss study of 42 overweight or obese men and women.
Across four weeks, men under 45-years-old lost more than 16 percent of their body fat, while women in the same age group lost only eight percent. To do this men were limited to 2,000 calories per day and women to 1,500 calories - a drop from the recommended intake of 2,500 calories and 2,000 calories respectively.
However, there was no difference in fat loss between males and females older than 45, with both sexes losing around 10 percent of their body fat.
Professor Alexandra Johnstone from the Rowett Institute at Aberdeen University added: "This is an interesting collaborative study, where the Rowett Institute team were able to contribute the human studies data, to explore this novel hypothesis."
While the findings are of interest, a larger human study investigating the impact of age and sex is needed to confirm these findings, the experts say.
