To investigate the correlation of peripheral insulin concentrations with food intake and body weight.Design:
Cross sectional and longitudinal clinical study: we investigated the association of peripheral insulin concentrations in response to an oral glucose tolerance test (OGTT) with subsequent measures of ad libitum food intake and body weight change.Subjects:
Food intake analysis: Pima Indians (n = 67, 63% male; body mass index (mean±s.d.) 34.2±9.4 kgm-2) with normal glucose regulation (NGR; fasting glucose <5.6 mmol l-1 and 2-h glucose <7.8 mmol l-1) participated in a study of ad libitum food intake measured over 3 days by an automated vending machine system. Weight change analysis: Pima Indians with NGR (n = 339) who also participated in a longitudinal study of risks for type 2 diabetes and had follow-up weights.Results:
Food intake analysis: incremental area under the curve (iAUC) for insulin during the OGTT was negatively associated with mean daily ad libitum energy intake (DEI) (r = -0.26, P = 0.04), calories consumed as percent weight-maintenance energy needs (%WMEN) (r = -0.38, P = 0.002) and carbohydrate intake (gram per day) (r = -0.35, P = 0.005). Adjustment for age and sex attenuated the association of iAUC with DEI (P = 0.06) not with %WMEN and carbohydrate intake (P = 0.005, P = 0.008). Weight change analysis: after adjustment for age, sex, follow-up time and initial body weight, higher insulin iAUC predicted less absolute and percent weight change (β = -6.9, P = 0.02; β = -0.08, P = 0.008, respectively).Conclusions:
In healthy Pima Indians with NGR, higher plasma iAUC during an OGTT predicted lower food intake and carbohydrate consumption and less weight gain. These data indicated a role for peripheral insulin as a negative feedback signal in the regulation of energy intake and body weight.