Diet strategies for maintaining substantial therapeutic weight loss: 78-week mixed methods randomised trial

Formula low-energy diets (LED), used intermittently, may assist long-term weight-loss maintenance (WLM). This study compared total diet replacement 2 days/week (5:2TDR) and once-daily meal-replacements (DMR), delivered within a structured WLM programme.

A 78-week randomised trial was conducted in 63 individuals (75 % female, BMI 23-61 kg/m²), recruited between 12/04/2016 to 05/06/2018, after documented mean (SD) intentional weight-loss >8 kg, achieved using LED, behavioural programmes, or pharmacotherapy. Participants who had received anti-obesity medications were either weight stable or regaining after drug withdrawal. The primary outcome was weight change at 26-weeks following randomisation. Six dietitians and 25/63 (40 %) participants completed qualitative interviews at 26-weeks. Between-group differences were assessed using repeated ANCOVA adjusting for baseline values applying Intention-to-Treat, Per-Protocol, and As-Treated methods.

At 26-weeks, 32/33 (97 %) randomised to 5:2TDR, and 29/30 (97 %) randomised to DMR, provided data. Four participants took pre-existing pharmacotherapy (n = 3 orlistat up to 78-weeks and n = 1 liraglutide up to 52-weeks). Mean (SD) pre-study weight-losses were similar between groups: 5:2TDR -15·0 (6·9) kg, DMR -18·8 (9·3) kg, p = 0.056. After 26-weeks WLM, intention-to-treat analysis found further weight-loss -0·9 kg (95 %CI -2·9, 1·5 kg) with 5:2TDR and regain with DMR 3·5 kg (95 %CI 1·3,5·5 kg); between-group difference -4·4 kg (95 %CI -7·3,-1·6 kg), p = 0·005. Maintained weight-losses at 26-weeks from pre-study start of weight loss were -15·8 (9·5) kg with 5:2TDR, -15·2 (10·5) kg with DMR, p = 0·977. Similar results were observed in the per protocol and as treated analyses. Both groups maintained weight losses >15 kg below baseline at 26, 52 and 78-weeks. Results were similar excluding those taking weight loss medications. Both interventions were well accepted. Dietitians successfully adapted LED interventions to overcome social/environmental challenges experienced by participants.

Structured dietary WLM is well accepted and can prevent weight regain after substantial loss, including after glucagon-like peptide-1 agonist withdrawal, and can maintain >15 kg loss up to 78-weeks TRIAL REGISTRATION: Clinicaltrials.gov: identifier NCT02683798.