Gender differences in changes in subcutaneous and intra-abdominal fat during weight reduction: an ultrasound study.
OBJECTIVE
In weight-reducing programs, men usually display greater improvement in metabolic risk factors than women. This gender difference may be related to enhanced weight and fat loss due to a greater energy deficit in men. To clarify the relationship between changes in metabolic profile, body fat composition, and weight loss, both sexes were studied under a regimen in which similar amounts of weight were lost.


METHODS
A cross-sectional study using anthropometric (body mass index and waist-to-hip ratio), impedance (bioelectrical impedance analysis) and ultrasound measurement methods (thickness of subcutaneous fat layers, intra-abdominal sagittal diameter) were conducted. The metabolic risk profile was determined by measuring lipids, lipoproteins, and blood pressure. The weight loss program lasted 15 weeks: 3 weeks under controlled conditions in the hospital and 12 weeks on an ambulatory basis. Patients were instructed to follow a mixed diet. Calorie intake was restricted to 1500 kcal/day for the men and 1200 kcal/day for the women. Thirty-two subjects with obesity (16 men and 16 women), with a mean body mass index of 35 kg/m2--matched with regard to age, height, and body weight--took part in the study.


RESULTS
As expected, weight loss was similar for both sexes (-13.4 kg vs. -12.8 kg). Also, body fat mass changed to the same extent in absolute and relative terms. The waist-to-hip ratio was identical before and after treatment in both sexes. The men lost more visceral fat than the women. This result is based on changes in intra-abdominal diameter as well as abdominal subcutaneous fat in relation to waist circumference. Changes in abdominal diameter were paralleled by reductions in triglycerides and increases in high-density lipoprotein-cholesterol. Subcutaneous fat loss was more pronounced in women than in men.


CONCLUSIONS
Where absolute and relative reductions in body weight and body fat are similar, men mobilize more intra-abdominal fat than women, whereas women lose more subcutaneous fat. The greater reduction in intra-abdominal fat seen in men is accompanied by a more pronounced improvement in the metabolic risk profile. Therefore, greater improvement of risk factors in men is not only related to a greater negative energy balance, as shown in most studies, but is also sex-specific.
Wirth
A
A
Teutoburger Wald Clinic, Bad Rothenfelde, Germany.
Steinmetz
B
B
D000005:Abdomen; D000273:Adipose Tissue / Q000000981:diagnostic imaging; D000293:Adolescent; D000328:Adult; D000368:Aged; D001823:Body Composition; D001824:Body Constitution; D015992:Body Mass Index; D003430:Cross-Sectional Studies; D017097:Electric Impedance; D002149:Energy Intake; D005260:Female; D006801:Humans; D008075:Lipoproteins, HDL / Q000097:blood; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000178:diet therapy*; D012727:Sex Characteristics; D014280:Triglycerides / Q000097:blood; D014463:Ultrasonography; D015431:Weight Loss
D008075:Lipoproteins, HDL; D014280:Triglycerides