Purpose - This study determined whether calcium co-ingestion potentiates postprandial GIP1–42 and GLP-1 concentrations in humans and the concomitant impact on insulin, appetite sensations and substrate metabolism.Methods - Ten healthy males consumed two energy- and macronutrient-matched meals in a double-blind, randomized, crossover design. The calcium content of the control meal was 3 mg/kg body mass, which was increased to 15 mg/kg body mass with calcium co-ingestion. Circulating concentrations of GIP1–42, GLP-1 and insulin were determined over a 180-min postprandial period, followed by 60 min of exercise. Visual analogue scales were used to determine subjective appetite sensations. Rates of energy expenditure and substrate (lipid and carbohydrate) oxidation were estimated using indirect calorimetry.Results - Calcium co-ingestion resulted in a 47 % increase in GIP1–42, a 22 % increase in GLP-1 and a 19 % increase in insulin areas under the curve for the 120 min following consumption (all P <0.05). Furthermore, appetite sensations were suppressed by calcium co-ingestion by 12 % (P = 0.034). No differences, however, were observed in substrate metabolism (P > 0.05).Conclusion - Ingestion of a high-calcium meal potentiates postprandial GIP1–42, GLP-1 and insulin concentrations in humans. Subjective appetite is also temporarily suppressed, although substrate metabolism is unaffected.