An evaluation of the long-term effectiveness of two adult community-based group weight management interventions

Abstract

Background: National guidance supports the provision of weight loss group programmes in a community setting using behavioural change methods as the first line intervention for adults (NICE, 2006) and post-natal women (NICE, 2010). The evidence base for the long-term effectiveness for such National Health Service-provided interventions is currently limited (Paul-Ebhohimhen & Avenell, 2009). The aim of this service evaluation of two types of community-based, group weight management, 6-week courses in a multicultural deprived inner city area was to determine whether the weight loss achieved over 6 weeks was sustained over the long term, thus demonstrating that these courses are effective. Methods: All 167 clients, who had attended four or more sessions of a 6-week long Size Down or Post-Natal Size Down weight loss course between 6 and 24 months ago, were telephoned with the purpose of completing a telephone questionnaire to determine a recent weight measure. At least two attempts were made to contact each client. In addition, those who had attended the Post-Natal Size Down course were offered a home visit with electronic scales to obtain a weight measure aiming to lend validity to the reported weights from the telephone questionnaire. The weights obtained were compared with the clients’ weights on completion of the course. Verbal consent was obtained. Results: Seventy-four clients (72 female and two male) completed the telephone questionnaire. Ninety-three (56%) clients were noncontactable. Recent weight measures were obtained for 65 clients, 17 of which were obtained by a home visit. Nine clients refused to report their weight. Since completing the course, 31 (42%) clients had continued to lose weight with a mean further weight loss of 5.5% (Size Down, 4.3%; Post-Natal Size Down, 9%) (range 0.1–21.9%), in addition to the mean weight loss of 1.9% (Size Down, 1.7%; Post-Natal Size Down, 2.2%) over the 6-week course. Twenty-one (28%) clients had maintained their weight and 13 (18%) had gained weight. Overall mean weight change for all clients from the beginning of the course to the telephone questionnaire was −3.8% (Size Down, −3.9%; Post-Natal Size Down, −3.6%). Further analysis of all the 38 clients that had completed both courses ≥12 months ago (mean 17.5 months; range 12–25 months) demonstrated a mean −4.1 kg (3.9%) weight change from baseline weight. Discussion: Given that further weight loss or weight maintenance is reportedly unachievable over the long term for the majority of those who attend weight management groups (Wing, 2005), these data suggest a more positive outcome for these two particular interventions, with two-thirds of clients either continuing to lose more weight or being able to maintain the weight initially lost. The further analysis of the group weight change from baseline values compares favourably with a recent Cochrane review on weight loss interventions (Norris et al., 2009) where, after 1 year, baseline weight was reduced by 2.8 kg (3.3%). The limitations of this evaluation are the accuracy of the telephone interview for obtaining weight data because these weights were self-reported; the majority of the clients were female; the sample size used was small with a large number of clients noncontactable. Conclusions: This service evaluation of Size Down and Post-Natal Size Down suggests that the weight loss achieved over 6 weeks was successfully sustained by two-thirds of the clients over the long term, and that these particular interventions are effective. Further evaluation using actual weight measures and including more male clients is needed.