In a diet for women aimed at losing body fat, with the typical reduction of calories, carbohydrates, and the increase of physical activity, what are the side effects that can be found on the health of patients? A study takes stock of the situation for the first time , taking a sample of female patients from the world of fitness (the first study of its kind) who tend to be normal weight and first subjecting them to a low-calorie diet for women with fewer carbohydrates and more proteins (the classic low-calorie diet but not a low-carb one) and after a few months of eucaloric diet, i.e. with normal calories. The sample was observed both immediately after the low-calorie diet and after the normal-calorie period. Here’s what the researchers of theFaculty of Sport and Health Sciences at the University of Jyväskylä who conducted the study. 

DIET FOR WOMEN: THE CONSEQUENCES OF A HYPOCALORIC REGIME
+ TRAINING WITH INCREASED AEROBIC WORK ON FEMALE HEALTH

Variations found immediately after 4 months of diet with prevalent loss of body fat and minimal loss of lean mass on a sample of 27 sports women.
1) Hormonal problems: especially the concentrations of leptin, T3, testosterone and estradiol have decreased. Menstrual irregularities have occurred. The problems were only partially resolved after 3-4 months of a normocaloric diet and reduction of aerobic activity: testosterone and T3 were however reduced compared to the pre-diet conditions.
2) Maintenance of muscle mass or slight decrease, but no progress in training. The athletes, while training not only aerobically, did not have any progress in increasing muscle mass, at the limit there was a slight decrease.

Especially according to point 1, the researchers recommend not to prolong the diet for too long without foreseeing an equally long time of normocaloric regimen.