Background/Objectives: There have been no studies examining the efficacy of meal replacement (MR) on weight loss and metabolic syndrome (MS) improvement in Southeast Asians. Thus, we undertook a 12-week randomised trial to evaluate the effect of a lifestyle education intervention alone (LEI) or with partial MR (LEI + MR) in obese Thai adults with MS.

Subjects/Methods: A total of 110 patients were randomised to receive either LEI or LEI + MR. Both groups received LEI to achieve weight loss. LEI + MR group additionally received two MR daily to replace either breakfast, lunch or dinner. Mean ± SE body mass index of all participants was 34.6 ± 0.6 kg/m2, mean ± SE age was 42.5 ± 1.1 years and 83% of patients were female. Both groups were compared for anthropometric and cardiometabolic indices at 12-week. Body weight was also compared at weeks 38 and 64.

Results: At 12 weeks, both groups exhibited statistically significant percentage weight loss (%WL) compared to initial weight but greater %WL was observed in LEI + MR compared to LEI, 2.9% vs. 1.5%, respectively (p < 0.05). MS criteria such as waist circumference and blood pressure improved significantly in both groups compared to baseline. However, improvement in fasting plasma glucose (FPG) was only significant in LEI + MR, and more participants with impaired FPG at baseline in LEI + MR (42.9%) than LEI (19%) returned to normal FPG at 12 weeks (p < 0.05). HbA1c, fasting insulin and HOMA-IR in LEI + MR were significantly lower than with LEI. At the end of the 12-week intervention period, 16% of participants no longer fulfilled MS criteria. A statistically significant weight loss from baseline persisted until 38 weeks but no longer reached statistically significant difference between groups.

Conclusions: LEI and LEI + MR were acceptable and led to improvement in weight and MS. LEI + MR group exhibited additional weight reduction and glycemic benefits at 12 weeks.