To investigate the status of muscle mass loss with obesity among young and middle-aged weight loss patients in nutrition clinic, and to analyze the risk factors of muscle mass loss with obesity.

318 cases of weight loss in the nutrition clinic of Changsha Central Hospital were investigated retrospectively. All subjects completed height and weight measurements, calculated body mass index (BMI), and measured skeletal muscle mass of limbs with Inbody 270 body composition analyzer. According to the muscle mass and body fat percentage, they can be divided into muscle mass loss combined with obesity group, simple obesity group, simple muscle mass loss group and normal group. The differences in body composition and the incidence of metabolic abnormalities between groups were compared, and the risk factors of muscle mass reduction combined with obesity were analyzed by logistic regression.

(1) The detection rate of muscle mass loss combined with obesity was 4.7%(15/318), including 5 males and 10 females. In addition, there were 269 cases of simple obesity, 34 cases of normal, no simple loss of muscle mass. (2) Compared with the muscle mass loss combined with obesity group, the simple obesity group had a higher proportion of family history of obesity, history of exercise and nonalcoholic fatty liver disease (NAFLD) (all P<0.05), and a lower proportion of sleep time ≥7 hours (P<0.05). The proportion of patients with exercise history was higher in the normal group (P<0.05). Compared with the simple obesity group, the normal group had a lower proportion of family history of obesity and NAFLD (all P<0.05), and a higher proportion of exercise history and sleep duration ≥7 hours (all P<0.05). (3) Compared with the muscle mass loss combined with obesity group, the body composition indexes of the simple obesity group were higher (all P<0.05); Compared with the muscle mass loss combined with obesity group, the height, body water, skeletal muscle mass, limb muscle mass and basal metabolism of the normal group were higher (all P<0.05), but the body fat, body fat percentage and visceral fat grade of the normal group were lower (all P<0.05). Compared with the simple obesity group, the normal group had lower body weight, body fat, body fat percentage, BMI and visceral fat grade (all P<0.05). (4) There were no significant difference in the incidence of abnormal blood pressure, blood glucose, blood lipid and uric acid levels among the three groups (all P>0.05). (5) Logistic regression analysis showed that exercise history was a protective factor for muscle mass loss (OR=0.164, P=0.026).

The prevalence of muscle mass loss with obesity was 4.7% in young and middle-aged overweight and obese people. These people tend to move less, sleep more. No higher incidence of metabolic abnormalities was found. Exercise was a protective factor against loss of muscle mass.

Obesity; Muscle mass loss; Body composition; Risk factors; Young and middle-age; Body fat percentage