Effects of solid versus liquid meal-replacement products of similar energy content on hunger, satiety, and appetite-regulating hormones in older adults

Objective: To examine whether solid versus liquid meal-replacement products differentially affect appetite and appetite-regulating hormones in older adults. Methods: On two occasions, 9 subjects (age: 61 +/- 3 years; BMI: 25.6 +/- 1.3 kg/ml) consumed 25% of daily energy needs as solid or liquid meal-replacements of similar energy contents. Blood and appetite ratings were collected over 4 hours. Results: The post-prandial hunger composite (area under the curve) was lower following the solid versus liquid meal-replacement (p < 0.005) and remained below baseline over 4 hours (p < 0.05). Similar responses were observed with the desire to eat. The insulin and ghrelin composites were lower following the solid trial compared to the liquid [insulin: 5825 (range: 41376-11639) vs. 7170 (4472-14169) uIU/1.240 min, p < 0.01; ghrelin: -92798 (range: -269130-47528) vs. - 56152 (range: - 390855-30840) pg/ml . 240 min, p < 0.05]. Ghrelin also remained below baseline over 4 hours (p < 0.05). No differences in cholecystokinin and leptin were observed between products. Conclusion: The consumption of comparable meal-replacement products in solid versus liquid versions with similar energy contents led to differential appetitive responses and should not be viewed as dietary equivalents in older adults.