New research has shed light on why men tend to lose more weight than women when following the same ketogenic diet (KD) protocol. The findings reveal that biological sex significantly influences how the body responds to ketosis, due to differences in hormones, fat metabolism, muscle composition, and genetic expression.
The ketogenic diet, a high-fat, low-carbohydrate, moderate-protein approach, induces a state of ketosis where the body burns fat for energy instead of glucose. While the diet is widely promoted for weight loss, it appears to be more effective in men than women. In one clinical trial over 45 days, men lost an average of 11.63% of their body weight, while women lost 8.95%.
One major factor contributing to this disparity is how fat is stored and utilized. Men typically store fat viscerally (around internal organs), which is more metabolically active and easier to mobilize during ketosis. Women, on the other hand, tend to store fat subcutaneously, which is harder to break down. Additionally, men produce more fat-metabolizing bacteria in the gut, such as Bacteroidetes, enhancing their ability to use fat for energy.
Hormonal differences also play a crucial role. Testosterone promotes fat breakdown by increasing the number of β-adrenergic receptors in fat cells, which respond to norepinephrine and trigger lipolysis. In contrast, estrogen enhances the sensitivity of α-adrenergic receptors, which inhibit fat breakdown. These hormonal influences explain why premenopausal women may struggle more to lose fat on a ketogenic diet.
Women’s muscle fiber composition may also limit the effectiveness of ketosis. Females have more slow-twitch muscle fibers geared toward endurance, making them better suited to sustained aerobic exercise for weight loss than strict dietary interventions like KD. Furthermore, their metabolic response to food intake leans toward fat storage, while men are more likely to oxidize fatty acids for energy.
Another challenge for premenopausal women is the hormonal fluctuation during the menstrual cycle, particularly in the luteal phase, which increases cravings for carbohydrates and reduces insulin sensitivity. These factors make it more difficult for women to achieve and maintain ketosis.
Despite some benefits of KD for both sexes, including appetite suppression, improved glucose control, and reduced fat accumulation, men appear to derive greater overall metabolic and hormonal advantages. Postmenopausal women may experience better results than younger women, likely due to lower estrogen levels.
The findings suggest that ketogenic diets may not be equally effective for everyone and underline the importance of personalized weight loss strategies that consider sex-based biological differences.
