Johns,D.J., Hartmann-Boyce,J., Jebb,S.A., Aveyard,P. and Behavioural Weight Management Review Group. J Acad Nutr Diet 114 (10):1557-1568 (2014)
OBJECTIVE: To evaluate whether combined behavioural weight management programs (BWMPs) involving both diet and physical activity elements lead to a greater weight loss at 12 months or longer than programs involving diet only or physical activity only in overweight and obese subjects.
DESIGN: Systematic review and meta-analysis of RCTs or quasiRCTs published in any language between May 2009 and November 2012. Databases searched were BIOSIS, CENTRAL, EMBASE, MEDLINE, PsycINFO, Science Citation Index, Cochrane database of systematic reviews, Conference Proceedings citation index, Database of abstracts of reviews and effects, and the Health technology assessment database. Studies predating the search dates were identified from another review (Loveman et al, 2011). Inclusion criteria were studies in adults aged 18+ years, classified as overweight or obese, that tested a clearly defined BWMP (both diet and behavioural components) in comparison with a diet only or physical activity only comparison, and measurement of weight change at 12 months or longer from baseline.
SETTING: 1 study was conducted in Sweden, 1 in Belgium and 6 in the USA.
PARTICIPANTS: Total of 1022 participants - adults aged 18+ years, classified as overweight (BMI>25) or obese (BMI>30) or >23 in Asian populations. The number of participants per study ranged from 59 to 352. Mean age ranged from 32 to 70 years and the majority of participants were women. Mean BMI ranged from 29.2 to 37.3.
MAIN OUTCOME MEASURES: The primary outcome was mean weight change (kg) at 12-18 months, calculated using ‘baseline observation carried forward’ (BOCF) - an intention-to treat analysis that assumes the weight of those who do not attend an assessment has not changed since baseline. As none of the included studies had reported BOCF it was calculated using complete case data. Where reported data were also extracted at 3 to 6 months follow-up. Separate random effects meta-analyses were conducted for comparisons with diet only and physical activity only arms.
RESULTS: Of 8 included studies, 7 compared BWMPs with diet only comparisons and 5 with physical activity only comparisons. Seven studies reported data at 12 months and 1 at 18 months. Mean weight loss at 3-6 months did not differ significantly between BWMPs and diet only arms (mean difference -0.62kg), but at 12 months BWMPs showed significantly higher weight loss than diet only programs (mean difference -1.72kg). Weight loss at 3-6 months was significantly higher in BWMPs than physical activity only programs (mean difference -5.33kg) and at 12 months (mean difference -6.29kg).
CONCLUSIONS: BWMPs combining diet and physical activity are more effective for weight loss over 12 months than interventions based on diet or physical activity alone. Practitioners can best support patients by helping them to increase physical activity and reduce energy intake within the context of BWMPs.
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