Background/Objectives:To investigate acceptability and tolerability of diets of different protein and glycemic index (GI) content aimed at weight maintenance following a phase of rapid weight loss, as part of a large pan-European dietary intervention trial.Subjects/Methods:The Diogenes study (www.diogenes-eu.org) consisted of an initial 8-week rapid weight-loss phase (800-1000 kcal/day), followed by a 6-month weight maintenance intervention with five different diets varying in protein and GI content. Measurement of a range of outcomes relating to experience of the Diogenes diets in terms of acceptability, experience and mood were recorded via end of day questionnaires throughout the study.Results:Weight change during the initial weight loss phase weakly, but positively correlated with acceptability of the programme (r range=-0.08 to 0.2, P0.05, n=685 on four of five dimensions). Success at weight maintenance positively correlated with acceptance of the programme (r range=-0.21 to -0.34, P