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/m (2)) 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: 4676-11639) VS. 7170 (4472-14169) uIU/l x 240 min, p<0.01; ghrelin: -92798 (range: -269130-47528) VS. -56152 (range: -390855-30840) pg/ml x 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.