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Analysis Reveals That Slimming World Programme Successfully Helps People Of All Sizes To Lose Weight Equally, While Men Do Better Than Women

A new study of 1.2 million self-funded Slimming World members – presented at this year’s European Congress on Obesity in Liverpool, UK – reveals that people of all sizes, from slightly overweight to severely overweight in the higher body-mass index (BMI) range are equally likely to lose weight through a programme based on healthy lifestyle behaviour change. The research, the largest ever audit of a lifestyle-based weight management programme, was conducted by Slimming World’s research team, led by Dr Jacquie Lavin at their headquarters in Alfreton, Derbyshire, UK.

Crucially, while many previous studies from a range of commercial weight loss services have focused on the small proportion of patients (approximately 2-5%) who are referred by their general practitioner or other health professional, this new study represents the approximately 95-98% of members who fund their own membership, so can be said to be representative of the overweight population at large.

The majority of adults in the UK–around 30 million people–are now overweight or obese. Weight management on a national scale requires behavioural and lifestyle solutions that are accessible to large numbers of people. Slimming World holds over 10,000 weekly weight management groups in community venues across the UK supporting up to 500,000 people each week. Members have their weight changes recorded on a digital card system so that their progress can be monitored throughout their membership. Some members opt for relatively short periods attending group sessions because they have less weight to lose. Others, especially those with higher body-mass index (BMI)–which places them in the obese category at the beginning of their weight loss journey–benefit from long-term support to help them reach their goals.

In this study, the digitally collected weekly weight records were collated for self-funding members of Slimming World joining between January 2010 and April 2012. Weight change outcomes in 1,264,291 adult participants during their first three months’ attendance have been analysed. A separate abstract analyses weight outcomes from the same cohort for nearly 72,000 members who engaged with the programme for 12 months.

Mean BMI for the 1.2 million at the start of the programme was 32.6kg/m2, mean age was 42 years and 5% of the programme’s users (63,123) were men. Overall, at the end of three months, BMI change across the whole study group was -1.5kg/m2, weight change -4.2kg, percent weight change -4.7%. Sessions attended varied from two to 13.

For participants attending at least 75% of sessions (478,772 members), mean BMI change was -2.5kg/m2, weight change -6.8kg, and percent weight change -7.5%. Longer term analysis of the 71,989 high-engagers who, between January 2010 and June 2011 had attended at least 75% of sessions over a 12 month period (and presented in a separate abstract) shows that members who engage for longer tend to have a higher BMI at baseline (mean 34.5kg/m2). The mean number of weeks attended was 45.4 (85.7% of possible sessions) with -12.7kg weight change, a percent weight loss of 13.2%, and BMI change of -4.7kg/m2.

Further analysis revealed that men had attended on average nine sessions over the three months, compared with eight for women. A greater proportion of men featured in the higher BMI categories before starting: almost half (46%) of male joiners had a BMI over 35kg/m2 with 20% over 40kg/m2. This is compared to women, of whom 29% of joiners had BMIs over 35kg/m2 with one in eight (12%) over 40kg/m2. Men were found to lose more weight than women: 7kg on average compared with 4kg for women. Average per cent weight loss was 6.1% for men and 4.6% for women.

Overall the programme was equally effective across the whole range of BMIs, with average weight loss for those with a BMI under 30 kg/m2 (classed as overweight) being 4.5%; those with BMI 30-35 kg/m2 (obese) and 35-40 kg/m2 (very obese) both 4.8%, and the highest BMI group, over 40 (severely obese) 4.7%.

Dr Lavin says: “This is the largest ever audit of a lifestyle-based weight management programme, and is proof that Slimming World has a significant impact on the health of the nation. Our programme is a practical option for weight management strategies in the community, achieving large-scale, clinically safe and effective weight loss. These results also confirm that whether you have a small or larger amount of weight to lose the programme is equally effective, contradicting a popular belief that people who have a significant amount of weight to lose need more radical solutions. While the 1.2 million dataset looks at weight losses over members’ first three months, the analysis we’ve done for nearly 72,000 members that stayed with us for 12 months shows a clinically significant mean weight loss of 13.2%.

“This data also gives a clear indication that members who attend sessions most frequently and regularly – at least 9 sessions over their initial three months – achieve the highest weight losses. And, as our 12 month data shows, those who have a great deal of weight to lose benefit most from ongoing regular support for behaviour change to adopt new healthy eating and activity habits. Every week at group sessions members discuss ways to overcome emotional and psychological as well as physical barriers to their success. They share practical tips and ideas in a safe, compassionate and powerfully motivating environment facilitated by highly trained consultants who are former members.

She adds: “From a government perspective, this study is particularly good news because it shows that many people have been able to lose weight after referring themselves at no cost to the NHS, and will continue to do so.

“This study refers to self-referring members, which represent the vast majority of our membership. However, with around two-thirds of UK adults now overweight or obese, it’s essential that health authorities across the UK continue to strengthen their relationship with commercial weight management programmes such as Slimming World so that they can also refer their patients to help them lose weight, become healthier, and avoid the impact of chronic weight-related diseases such as diabetes, heart disease and other consequences of obesity.”

Asked why men appear to do better than women, Dr Lavin adds: “The size of this dataset is unprecedented and we’re only just scratching the surface of the insights it will give us. Our initial analysis shows that men lose a little more weight than women, but we haven’t yet been able to analyse why that is. There’s a huge opportunity to interrogate the data more deeply and something that we will keep our research team busy for some time. What is good news however is that the data shows that all our members are losing weight – men, women, those with higher BMIs and those from some of the most deprived areas of the country. The most important message coming through from the data is that those who engage regularly and consistently attend weight loss sessions are the most likely to successfully lose weight.”


Link to abstract 1

Link to abstract 2

Link to abstract 3

Breakdown of the 1.2 million participants in the study by local authority area

Source: Slimming World