Calorie controlled diets vary in their impact and are strongly influenced by age and sex, according to the findings of a study led by the University of Edinburgh.
Researchers found that dieting affects males and females differently in young adulthood, with males showing more significant fat loss and improved blood sugar levels than females.
The dieting differences disappear with age and could be linked to oestrogen, one of the main female sex hormones.
The findings are published in the journal eLife and could help identify who would most benefit from calorie controlled dieting.
Maintaining a healthy weight is linked to the prevention of conditions such as obesity, high blood pressure, type 2 diabetes and an increased life expectancy. Calorie controlled dieting, when combined with the intake of essential nutrients, can be one way to maintain a healthy weight.
By looking at the impact of a reduced calorie diet on both mice and humans, the researchers investigated the influence of age and sex on the health benefits of dieting.
Over six weeks, the scientists analysed the impact of age and sex on dieting using 96 mice whose daily calorie consumption was reduced by 30 percent and 85 mice on a regular diet. Young male mice on a calorie restricted diet reduced their blood sugar levels by 22 percent over the study, compared to a 16 percent lowering in the young female mice. The dieting also led to a nearly 70 percent decrease in fat mass for males but almost no fat loss at all for females.
The scientists believe that the young female mice had less fat loss because they limited the breakdown of body fat, used less energy, and produced more fat after meals.
By contrast, when dieting began at older ages, there was no significant difference in fat loss between the sexes. Both male and female mice lost around half of their body fat on the calorie controlled diet.
The researchers also analysed data from 42 overweight or obese men and women, and the same patterns of blood sugar levels and weight loss occurred.
The researchers found that over a four-week period, men under 45 years of age lost more than 16% of their body fat, whilst females in the same age range lost half this amount. For older men and women, there was no difference in weight loss, with each sex losing 10 percent of thier body fat as a result of the calorie-controlled diet.
The researchers suggest that a more extensive study is needed to confirm the findings in humans.
Dr William Cawthorn, who led the study and is based at the University of Edinburgh, 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.’
He added: ‘This could help us to devise improved nutritional strategies to prevent diseases and promote healthy ageing.’