Background  

Bariatric surgery is considered the most effective treatment for reducing excess body weight and maintaining weight loss (WL) in severely obese patients. There are limited data evaluating metabolic and body composition changes after different treatments in type III obese (body mass index [BMI] > 40 kg/m²).

Methods  

Twenty patients (9 males, 11 females; 37.6 ± 8 years; BMI = 50.1 ± 8 kg/m²) treated with dietary therapy and lifestyle correction (group 1) have been compared with 20 matched patients (41.8 ± 6 years; BMI = 50.4 ± 6 kg/m²) treated with laparoscopic gastric bypass (LGBP; group 2). Patients have been evaluated before treatment and after >10% WL obtained on average 6 weeks after LGBP and 30 weeks after integrated medical treatment. Metabolic syndrome (MS) was evaluated using the Adult Treatment Panel III/America Heart Association (ATP III/AHA) criteria. Resting metabolic rate (RMR) and respiratory quotient (RQ) was assessed with indirect calorimetry; body composition with bioimpedance analysis.

Results  

At entry, RMR/fat-free mass (FFM) was 34.2 ± 7 kcal/24 h·kg in group 1 and 35.1 ± 8 kcal/24 h·kg in group 2 and did not decrease in both groups after 10% WL (31.8 ± 6 vs 34.0 ± 6). Percent FFM and fat mass (FM) was 50.7 ± 7% and 49.3 ± 7% in group 1 and 52.1 ± 6% and 47.9 ± 6% in group 2, respectively (p = n.s.). After WL, body composition significantly changed only in group 1 (% FFM increased to 55.9 ± 6 and % FM decreased to 44.1 ± 6; p = 0.002).

Conclusion  

After >10% WL, MS prevalence decreases precociously in surgically treated patients; some improvements in body composition are observed in nonsurgically treated patients only. Further investigations are needed to evaluate long-term effects of bariatric surgery on body composition and RMR after stable WL.