Changes in Cardiotrophin-1 and Fibroblast Growth Factor-21 with Weight Loss

Abstract

The purpose of this investigation was to examine the effects of modest weight loss on circulating concentrations of cardiotrophin-1 (CT-1) and fibroblast growth factor-21 (FGF-21) in obese men. Nine obese men (age = 41.5 ± 7.1; weight = 101.7 ± 21.0 kg; BMI = 32.8 ± 3.6 kg/m2; % fat = 35.2 ± 4.3) were assigned to either an exercise or dietary restriction intervention. Seven age-matched controls (age = 42.3 ± 8.5; weight = 74.5 ± 5.0 kg; BMI = 24.8 ± 1.4 kg/m2; % fat = 25.2 ± 5.5) served for comparison purposes. Control individuals were not assigned to an intervention. The overall targeted weight loss for both interventions was 8 to 10% of initial body weight over a 6 to 10 month period. A blood sample and DEXA scan were obtained for each participant at baseline and every four weeks during the intervention in the obese group. Blood samples were analyzed for CT-1, FGF-21, glucose, insulin, non-esterified fatty acids (NEFA), adiponectin, IL-6, TNF-α, myeloperoxidase (MPO), and total antioxidant capacity (TAC). Glucose to insulin ratio (GIR), homeostasis model index (HOMA) and the quantitative insulin sensitivity check index (QUICKI) were used as clinical indexes of metabolic health. Differences between groups were determined by independent t-test. Changes in blood variables were determined by repeated measures ANOVA and paired t-test. Pearson product moment correlation coefficients were used to determine the relationship between baseline physiological and metabolic characteristics and dependent variables (p < 0.05 for all). Neither CT-1 nor FGF-21 concentrations differed between groups at baseline. No significant change in CT-1 concentrations occurred with 8 to 10% weight loss. FGF-21 concentrations significantly decreased by 57.3% after weight loss of 8 to 10%. Significant reductions in total and regional body fat, lean mass, insulin, GIR, HOMA and QUICKI also occurred with weight loss. Reductions in FGF-21 occurred along with those in total and regional body fat and improvements in insulin sensitivity. These results indicate that FGF-21 may be a potential clinical indicator of improvements in metabolic regulation that occur with modest weight loss.