Summary: In 56 predominantly Maori adults with obesity and raised HbA1c in Tairawhiti, New Zealand, a 10-week whole-food plant-based (WFPB) community programme produced a significant between-group weight loss of 3.3 kg versus a waitlist control (95% CI 0.8 to 5.7, p<0.001). The randomised comparison showed no significant effect on HbA1c (p=0.08), cholesterol (p=0.69) or waist circumference (p=0.16); larger figures of 5 kg loss and a 3 kg loss sustained at 36 months come from uncontrolled within-group follow-up.
PICO Summary
| Element | Detail |
|---|---|
| Population | 56 adults aged 30 to 72 with obesity (BMI 30 or above) and HbA1c 40 mmol/mol or above; 59% identified as Maori, 5% as Pasifika. Single Very-Low-Cost-Access general practice clinic, Gisborne, New Zealand. Randomised waitlist-controlled trial. |
| Intervention | 10-week WFPB community programme: 2-hour sessions twice weekly (40 hours total) of skills-based learning and health education, plus dietary change. |
| Comparison | Waitlist control receiving no intervention during the 10-week study period (later crossed over to the programme). |
| Outcome | Between-group intention-to-treat at 10 weeks: weight loss 3.3 kg (95% CI 0.8 to 5.7, p<0.001), the only significant difference. HbA1c reduction was a non-significant trend (3.2 mmol/mol, 95% CI -0.4 to 6.7, p=0.08); cholesterol (p=0.69), waist circumference (p=0.16) and activity level (p=0.97) did not differ. Within-group (uncontrolled, all participants treated): 5 kg loss post-treatment with 3 kg sustained at 36 months (95% CI 1.2 to 4.7, p<0.001) and a sustained 6 cm waist reduction; post-treatment HbA1c and cholesterol falls were not sustained. |
WFPB community programme in a Maori cohort
RCT · obesity + raised HbA1c · 10 weeks
A 10-week plant-based community programme cut weight by a significant 3.3 kg versus waitlist, but had no significant effect on HbA1c, cholesterol or waist circumference. The larger sustained-loss figures come from uncontrolled within-group follow-up.
Expert Commentary
The honest verdict is that this trial demonstrates modest, durable weight loss from a culturally grounded plant-based programme, and little more that is controlled. Only weight reached significance against the waitlist arm at ten weeks; HbA1c, cholesterol and waist circumference did not, so the headline glycaemic claim is not supported by the randomised data. The striking 5 kg and 36-month 3 kg figures are derived from within-group analyses after every participant had been treated, where there is no concurrent comparator and regression to the mean and secular change cannot be excluded. They should be read as encouraging signals, not proof of sustained metabolic benefit. The principal limitation is the small sample of 56 in a single very-low-cost clinic, which leaves the study underpowered for HbA1c and limits generalisability; the authors themselves note that HbA1c follow-up was constrained by inadequate data capture. The open-label design is unavoidable for a dietary programme but invites performance and reporting bias, and one author is affiliated with a plant-based health trust, a potential interest worth flagging. Can I use this with my patients? Cautiously yes, for a motivated Maori or Pasifika patient with obesity seeking a community weight-management option, framed as a weight intervention rather than a glycaemic cure. I would welcome an adequately powered multi-site trial with biochemical endpoints before stronger claims are made.
References
Smith M, Wright N, McHugh P, Duncan B, Chwyl C. Randomised waitlist-controlled trial of a 10-week community programme using a plant-based diet in a predominantly Maori population in Tairawhiti (Gisborne). BMJ Open. 2025;15(6):e080946. doi:10.1136/bmjopen-2023-080946