A recent research study has shed light on the impact of reduced calorie diets on males and females, highlighting notable differences in fat loss and blood sugar levels. The findings suggest that the female sex hormone, estrogen, may play a role in determining the health benefits of dieting. Understanding these differences could aid in identifying individuals who would benefit most from restricted calorie diets.
The University of Edinburgh-led research team conducted a comprehensive study involving both mice and humans. The six-week study observed 96 mice on a reduced calorie diet (30% less than normal) and 85 mice on a normal diet. Results showed that the reduced calorie diet led to a 22% decrease in blood sugar levels in young males, while young females experienced a 16% decrease.
The impact on body fat was even more striking, as males saw a nearly 70% reduction in fat mass, whereas females showed no fat loss at all. The study revealed that young female mice resisted fat loss due to limited breakdown of body fat, lower energy expenditure, and increased fat production after meals compared to males.
Interestingly, when dieting commenced at older ages, there was no significant difference in fat loss between sexes. Both female and male mice lost approximately half of their body fat.
To validate these findings, a small human weight loss study involving 42 overweight or obese participants was conducted. The study confirmed that age and sex-based differences exist in humans as well. Men under 45 years old experienced over 16% fat loss, while women in the same age group only lost 8%. However, there was no significant difference in fat loss between males and females older than 45, with both groups losing around 10% of their body fat.
Although the human study was not initially designed to explore the influence of age and sex on dieting, the researchers retrospectively analyzed the data to address this aspect. To further validate these findings, experts suggest conducting a larger human study focused on investigating the impact of age and sex.
Published in the journal eLife, this study involved an international research team from prestigious institutions such as the Universities of Edinburgh, Aberdeen, the Highlands and Islands, Glasgow, the Tri-Service General Hospital in Taiwan, and the National Center for Global Health and Medicine in Tokyo.
These findings highlight the numerous health benefits of reduced-calorie diets and their potential to promote healthy aging. The study’s novel discovery that sex differences largely disappear when dieting begins at older ages holds promise for devising improved nutritional strategies to prevent diseases and promote overall well-being.