Changes in Health-Related Behaviours Among Adults Who Accessed Real-World Weight Management Support: 12-Month Outcomes

TL;DR

A weight management program helped adults lose weight and improve diet, activity, and mental health over a year, with benefits extending to family members.

Contribution

Demonstrates sustained health behavior changes and positive spillover effects on family habits in a real-world weight management program.

Findings

Members achieved a 7.5% mean weight loss at 12 months with improved diet quality and physical activity.

Participants reported influencing family members to adopt healthier eating and activity habits, which persisted over time.

Mental well-being scores were consistently higher in program members compared to a reference group.

Abstract

Background

Large weight losses are desirable, but their benefits are short-lived without sustained behaviour changes that can be maintained at the household level. This longitudinal study, conducted in a real-life setting, investigated changes in weight, dietary habits, activity levels, and physical and mental well-being of members of a community weight management programme (Slimming World), compared with a matched cross-sectional reference group from the general population. The wider influence on the dietary and activity habits of family members was also explored.

Methods

Longitudinal data were collected from members at 0-4 weeks (T1), 3 months (T2), and 12 months (T4) after joining. The reference group completed surveys at each time point. Diet quality scores (NDQS) were calculated using a validated tool, hours of moderate-intensity physical activity were recorded, and mental well-being was assessed using adapted items from the SF Health Survey. Changes in members’ behaviours and comparisons with the reference group were analysed using within- and between-group ANOVAs with p-adjusted post-hoc comparisons.

Results

Of the 1,884 members who provided baseline data, 174 (7.5% male) completed surveys at T1, T2, and T4. At baseline, mean BMI and age were 34.7 ± 7.0 kg/m² and 53.0 ± 12.0 years, respectively. Mean weight change at 12 months was -7.5%. Member NDQS increased from baseline to T1 (11.5 ± 3.2 vs 14.1 ± 2.4, p < 0.001), T2 (14.3 ± 2.7), and T4 (14.1 ± 2.9) (both p < 0.05). Physical activity increased between T1 and T2 (4.6 ± 7.4 vs 6.7 ± 10.1 hours/week, p < 0.01) and was maintained at T4 (6.5 ± 6.0, p < 0.05). At T1, T2, and T4, members had higher NDQS, greater levels of physical activity (p < 0.001), and higher mental well-being scores (p < 0.05) than the reference group. At T2, of the 122 members living with a partner, 79.5% reported influencing their partner to eat healthier meals. Among the 47 members living with children, 66.0% reported influencing them to eat healthier meals. The positive influence on partners’ and children’s eating behaviours observed at T2 remained stable at T4 (both p > 0.05). At T2, 40.7% of members reported encouraging others in their household to become more active, and this proportion remained consistent at T4 (40.5%, p > 0.05).

Conclusion

Although the low response rate across all three surveys is a limitation, the findings suggest that Slimming World’s behaviour change programme is effective in supporting adults (mainly females) living with obesity to make health-related behaviour changes. Members achieved clinically significant weight loss and improvements in diet quality, physical activity, and mental well-being compared with the reference group. These changes were maintained at 12 months, with an additional positive influence reported on family members’ lifestyle habits.

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