Diet strategies for maintaining substantial therapeutic weight loss: 78-week mixed methods randomised trial. (original) (raw)

Brosnahan, Naomi ORCID: https://orcid.org/0000-0002-3354-1060, Hankey, Catherine, Leeds, Anthony, Leslie, Wilma, Thom, George ORCID: https://orcid.org/0000-0002-8871-9524, Hutchison, Lisa, Govan, Lindsay ORCID: https://orcid.org/0000-0002-6447-9618, Ross, Hazel and Lean, Michael E.J. ORCID: https://orcid.org/0000-0003-2216-0083(2025) Diet strategies for maintaining substantial therapeutic weight loss: 78-week mixed methods randomised trial.Clinical Nutrition, 53, pp. 188-198. (doi: 10.1016/j.clnu.2025.08.009) (PMID:40934815)

Abstract

Background and Aim: 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. Methods: A 78-week randomised trial was conducted in 63 individuals (75% female, BMI 23-61kg/m2), recruited between 12/04/2016 to 05/06/2018, after documented mean (SD) intentional weight-loss >8kg, 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. Results: 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 -0·9kg (95%CI -2·9,1·5kg) with 5:2TDR and regain with DMR 3·5kg (95%CI 1·3,5·5kg); between-group difference -4·4kg (95%CI -7·3,-1·6kg), 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 >15kg 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. Conclusions: 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 >15kg loss up to 78-weeks. Trial registration: Clinicaltrials.gov: identifier NCT02683798.

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