Reduced Albumin Concentration Predicts Weight Gain and Higher Ad Libitum Energy Intake in Humans

OBJECTIVE: Circulating albumin is negatively associated with adiposity but whether it is associated with increased energy intake, lower energy expenditure or weight gain has not been examined. METHODS: In study 1 (n=238; 146 men), we evaluated whether fasting albumin concentration was associated with 24-h energy expenditure and ad libitum energy intake. In study 2 (n=325;167 men), we evaluated the association between plasma albumin and change in weight and body composition. RESULTS: After adjustment for known determinants of energy intake lower plasma albumin concentration was associated with greater total daily energy intake (β= 89.8 kcal/day per 0.1 g/dl difference in plasma albumin, p=0.0047). No associations were observed between plasma albumin concentrations and 24-h energy expenditure or 24-h respiratory quotient (p>0.2). Over 6 years, volunteers gained on average 7.5 ± 11.7 kg (p<0.0001). Lower albumin concentrations were associated with greater weight [β=3.53 kg, p=0.039 (adjusted for age, sex, follow up time), CI 0.16 to 6.21 per 1 g/dl difference albumin concentration] and fat mass (β=2.3 kg, p=0.022), respectively, but not with changes in fat free mass (p=0.06). CONCLUSIONS: Lower albumin concentrations were associated with increased ad libitum food intake and weight gain, indicating albumin as a marker of energy intake regulation. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov, identifiers NCT00340132, NCT00342732.