Objective: The study objective was to compare the effect of a standard calorie- and fat-restricted diet (STD-D) and a calorie- and fat-restricted lacto-ovo-vegetarian diet (LOV-D) on total and high-molecular-weight (HMW) adiponectin levels after 6 months of behavioral intervention.

Design: This study is an ancillary study to a randomized clinical trial.

Subjects: Subjects included 143 overweight/obese adults (STD-D = 79; LOV-D = 64).

Intervention: Both groups received the same standard behavioral intervention; the only difference was that LOV-D participants were instructed to eliminate meat, poultry, and fish from their diet.

Measures: Weight, dietary intake with the 3-day food diary, and total and HMW adiponectin levels were measured.

Results: Both groups significantly increased total (STD-D +7.2 ± 17.8%; LOV-D +9.4 ± 21.8%) and HMW adiponectin levels (STD-D +18.5 ± 32.9%; LOV-D +15.8 ± 34.5%; ps < 0.05) with no significant differences between the groups. We found significant associations between weight loss and increases in total (β (SE) = -.071(.27); p = 0.003) and HMW adiponectin (β (SE) = -1.37(.47); p = 0.001) levels independent of the diet type. Weight loss at the higher quartile was associated with improvements of adiponectin levels (p < 0.05).

Conclusion: Weight loss was associated with increased total and HMW adiponectin levels regardless of the diet type. Enhancing weight loss may be a means to improve adiponectin levels.