A recent study has shed new light on how the ketogenic diet impacts men and women differently, especially when it comes to weight loss.
According to researchers, men consistently experience greater fat loss than women under identical keto protocols, with biological sex playing a significant role in how the body responds to this popular dietary approach.
In one 45-day clinical trial reviewed in the study, men on the keto diet lost an average of 11.63% of their body weight, compared to 8.95% in women following the same regimen. The findings point to complex physiological and hormonal differences that affect how men and women burn fat, store energy, and adapt to carb-restricted eating plans like keto.
The ketogenic diet, which is high in fats, moderate in protein, and extremely low in carbohydrates, puts the body into a state of ketosis.
In this state, the liver produces ketone bodies — byproducts of fat metabolism — which the brain and body use as a primary energy source in place of glucose.
This metabolic shift not only reduces fat stores but also suppresses appetite and regulates blood sugar. However, the new research highlights that sex-specific biology significantly influences how effective a ketogenic diet is for weight loss.
One of the key factors is fat distribution. Men typically store fat viscerally while women tend to store fat subcutaneously.
Visceral fat is more readily metabolised during ketosis, giving men a physiological edge when it comes to shedding pounds on a ketogenic diet.
Hormonal differences also play a crucial role. Testosterone enhances fat-burning processes by increasing beta-adrenergic receptor activity, while oestrogen — especially in premenopausal women — can hinder fat breakdown.
Moreover, the menstrual cycle introduces additional metabolic variability for women. During the luteal phase, elevated progesterone levels reduce insulin sensitivity and increase cravings for carbohydrates, making it harder for many women to maintain ketosis.
Another contributing factor is how each sex uses energy. Men are more likely to burn fat for energy, while women often store fat and rely on carbohydrates as a primary fuel source. These metabolic tendencies can make fat loss more challenging for women on a low-carb diet like keto.
Even at the microbiome level, differences emerge. The study found that men generally have higher levels of fat-metabolising gut bacteria, which may enhance the fat-burning effects of the diet.
Interestingly, the review also noted that a ketogenic diet can support muscle growth, but potentially at a cost for women.
Some studies have shown that keto may contribute to increased muscle fatigue in young, healthy females, possibly affecting workout performance and overall weight loss outcomes.
The researchers concluded that the ketogenic diet is most effective for men and postmenopausal women, with more limited success observed in premenopausal women.
They emphasised the need for personalised dietary approaches that take sex, hormones, genetics, and lifestyle factors into account.
The authors also called for more diverse clinical research to validate these findings across different populations, stating that personalised nutrition could be the key to more effective obesity treatment in the future.
Read more in the journal Frontiers in Nutrition.