Resting energy expenditure and insulin resitance in obese patients, differences in women and men.

BACKGROUND AND OBJECTIVE: There is little research about the relation of REE and insulin resistance with gender. The aim of our work was to study gender differences in REE and insulin resistance in obese patients.

RESEARCH METHODS AND PROCEDURES: A population of 131 obesity patients was analyzed in a prospective way. The following variables were specifically recorded: age, smoking habit, drinking habit, weight, body mass index (BMI), waist circumference, and waist-hip ratio. Blood pressure, basal glucose, insulin, fibrinogen, and C-reactive protein. HOMA was calculated. An indirect calorimetry, tetrapolar electrical bioimpedance and a serial assessment of nutritional intake with 3 days written food records were performed.

RESULTS: The mean age was 31.7 +/- 9.2 years and the mean BMI 34.4 +/- 5.3. Cardiovascular risk factors were similar in both groups. Anthropometric measurements showed an average waist circunference (107.8 +/- 16.1 cm), waist-to hip ratio (0.93 +/- 0.11), and average weight (94.8 +/- 20.2 kg). Bipolar body electrical bioimpedance showed the next data; fat free mass (55.2 +/- 17.1 kg) and fat mass (35.7 +/- 12.3 kg). Indirect calorimetry showed higher resting metabolic rate (REE) in males (2001.7 +/- 443 Kcal/day vs. 1774.7 +/- 344 Kcal/day; p < 0.05). REE corrected by fat free mass was similar (male 34.2 +/- 17 Kcal/day/kg vs female 39 +/- 11.6 Kcal/day/kg; ns). Nutritional intake and HOMA were similar in males and females. In the multivariate analysis with a dependent variable (RMR), the fat free mass remained in the male model (F = 18.5; p < 0.05), with an increase of 17.8 (CI 95%: 9.1-26.2) kcal/day with each 1 kg of fat free mass adjusted by age. In the female model, the fat free mass remained in the model (F = 1 2.5; p < 0.05), with an increase of 15.2 (CI 95%: 6.3-24.2) kcal/day with each 1 kg of fat free mass adjusted by age.

CONCLUSION: REE was higher in males than females, with a higher influence of fat free mass in males than females. No association between insulin resistance and REE was detected.