Endocrine Abstracts

Background: Obesity (BMI< 30 kg/m²) is a chronic and progressive disease, that is associated with many co-morbidities such as cardiovascular and psychiatric diseases, cancer, and arthritis. Lifestyle interventions are the cornerstone of obesity treatment, but when ineffective, anti-obesity pharmacotherapy could be added. In recent years, several anti-obesity agents have been approved, such as the glucagon-like peptide -1 (GLP-1) analogue liraglutide. Liraglutide induces weight loss, presumably by suppressing appetite and improving satiety. It is however unclear whether liraglutide also induces weight loss by alterations of the resting energy expenditure (REE).

Methods: In this observational longitudinal study, we evaluated individuals with obesity who were treated with liraglutide 3.0 mg at the Obesity Center CGG, Erasmus MC Rotterdam, The Netherlands. We included 24 individuals (18 women), of whom four had a confirmed genetic obesity, thirteen had clinical features suspective of genetic obesity, and seven had common obesity. At baseline and after 16 weeks of treatment, which included dose escalation over a period of 4 weeks, we measured anthropometric parameters, body composition using bio-electrical impedance (Inbody S10, BioSpace, Seoul, Korea), and REE using indirect calorimetry (Q-NRG^®, Cosmed, Roma, Italy). Predicted REE was calculated using the Harris-Benedict formula.

Results: At baseline, mean weight and BMI were 124.1 kg (± 24.1) and 42.7 kg/m² (± 7.5), respectively. Their weight decreased significantly (-5.7%, n=23) after 12 weeks of treatment. Fat mass and fat-free mass (FFM) decreased significantly (-5.2 kg and -2.7 kg, respectively; n=18) and percentage of fat mass decreased from 47.6% to 46.5% (P=0.096). REE increased from 1879 kcal/day to 1956 kcal/day (P=0.150), and REE per kg FFM increased from 29.7 kcal/kg/day to 32.3 kcal/kg/day (P=0.023). Lastly, REE as a percentage of predicted REE increased from 94% to 98% (P=0.204).

Conclsion: In patients with obesity, treatment with GLP-1 analogue liraglutide effectively induces weight loss, with improved body composition. Furthermore, despite decreases in fat free mass, of which muscle mass is a major component, resting energy expenditure did not decrease. Our findings suggest that weight loss induced by liraglutide may not only be facilitated by decreases in caloric intake through the anorexigenic effects of GLP-1 analogues, but also by increasing the resting energy expenditure per kg fat-free mass.

Funding: EFCvR is funded by a Vidi grant from the Netherlands Organization of Scientific Research NWO/ZONMW (grant number: 91716453). EFCvR is financially supported by the Elisabeth Foundation.