Objectives: The primary aim was to determine whether ready-to-eat cereal used as a portion-controlled, meal replacement promotes weight loss. Additional aims were to determine whether weight loss differed if the cereal was provided as a single brand or variety of brands and whether this use of ready-to-eat cereal promotes continued weight loss following transition to a high-fiber, high-volume (Volumetric) diet.
Methods: Body composition was measured and diet records, appetite questionnaires and activity logs were completed during baseline and end of intervention weeks 2 and 6. Participants were assigned to one of four treatment groups. Group 1 (6 M, 22 F, mean age 43.0 +/- 1.9 years, mean initial BMI 28.9 +/- 0.4 kg/m(2)) consumed a serving of a single brand of ready-to-eat cereal with 2/3 C skim milk and a 100 Kcal portion of fruit for breakfast and as a replacement for either lunch or dinner for weeks 1 and 2. No restrictions were placed on the non-cereal meal. They then followed the Volumetric diet for weeks 3 to 6 with a target energy restriction of 500 kcal/day. Group 2 (3 M, 25 F, mean age 40.9 +/- 2.3 years, mean initial BMI 29.39 +/- 0.6 kg/m(2)) followed the same protocol, but was permitted to select from a variety of ready-to-eat cereals during weeks 1 and 2. Group 3 (7 M, 19 F, mean age 41.6 +/- 2.4 years, mean initial BMI 29.3 +/- 0.6 kg/m(2)) received no dietary instruction during the six-week study and Group 4 (9 M, 18 F, mean age 38.2 +/- 2.8 years, mean initial BMI 29.3 +/- 0.6 kg/m(2)) received no intervention prior to adoption of the Volumetric diet for weeks 3 to 6.
Results: The cereal interventions resulted in 640 +/- 109 and 617 +/- 105 kcal/day reductions of energy intake in Groups 1 and 2, respectively, during the two-week cereal intervention. This led to comparable mean weight losses (1.91 +/- 0.19 kg-Group 1, 1.37 +/- 0.15 kg-Group 2) that were significantly greater than that observed in Group 3 (0.08 +/- 0.15 kg). The losses were primarily of fat mass. No significant changes of total body water were observed. Weight loss continued during the Volumetric diet in Groups 1 and 2. The changes were comparable to those observed in Group 4, and all were significantly greater than that of Group 3. Self-reported hunger was slightly, but significantly higher than baseline in Groups 1 and 2 during the cereal intervention, but similar to baseline in Groups 1, 2 and 3 during the Volumetric diet. Based on predicted weight loss, compliance with the Volumetric diet was similar and limited in all three intervention groups.
Conclusions: Ready-to-eat cereals may be used to promote weight loss when consumed as a portion-controlled, meal replacement. Provision of a variety of brands does not compromise efficacy. Weight losses may be maintained or increased after transition to the Volumetric diet. The later regimen effectively controls hunger and may lead to weight loss, but compliance is limited.