Session: SUN 678-689-Adipocyte Biology
Poster Board SUN-689
Methods: Both 24h EE and 24h respiratory quotient (RQ) were measured using whole room indirect calorimetry in 50 healthy subjects (8 NA/ 13 C/ 17 H/ 12 AA; 35M/ 15F; mean±SD: age 35.8±9.8 y; BMI 26.9±4.4 kg/m2; %body fat 29.6±11.5%, 24h EE 2502±306 kcal; FPIC 411.9 ± 171.1 ng/mL) during 24h of fasting, 24h of energy balance (EB), and during 3 separate occasions of 24h of overfeeding (OF) with 200% of energy requirements with 1)low protein (3%), high fat (46%), 2)normal protein (20%), high fat (60%) and 3)high protein (30%), high fat (44%) diets. A weight maintaining diet was given for 3 days between dietary interventions. Body composition was measured using DXA. Plasma for FPIC was collected before and after each dietary intervention and measured using an ELISA assay kit (Phoenix Pharmaceuticals, Inc., Burlingame, CA).
Results: Fat free mass (β=9.6±3.5; p <0.01) was the only significant predictor of FPIC in a stepwise regression analysis to assess for determinants of FPIC. FPIC did not explain additional variance of 24h EE during EB beyond known determinants including age, sex, race, fat mass and fat free mass (p= 0.7), nor was it associated with RQ (p=0.4). The 24h EE increased by 2.9±4.8%, 7.4±7.9%, and 14.9±7.0%, respectively, during the low protein, normal protein and high protein OF diets. FPIC increased after OF with both the normal protein, high fat diet (Δ67.8±131.4 ng/mL; 95% CI = 29.7 to 105.9; p<0.01) and the high protein, high fat diet (Δ31.4±61.7 ng/mL; 95% CI = 8.8 to 54.1; p<0.01), but not the low protein diet (p=0.3). In mixed models, FPIC changes during OF were neither related to the percent increase in EE (p=0.6) nor absolute diet induced EE (p=0.5) after accounting for age, sex, race and diet.
Conclusion: FPIC is strongly associated with fat free mass but is not an independent contributor to sedentary 24h EE during EB in humans. Although, 24h of increased protein intake led to increases in FPIC, FPIC was not associated with the EE response to OF.
Nothing to Disclose: MS, PP, MH, JK, MST
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