The Lighten Up trial (1) compared weight loss in participants randomized to a variety of commercial weight-loss programs or one-on-one counselling services to a control group (free vouchers to a fitness club). Despite the many study limitations and the fact that the study was only powered to make comparisons to the control group, the concluding statement in the abstract is:
“Commercially provided weight management services are more effective and cheaper than primary care based services led by specially trained staff, which are ineffective.”
Jolly K, et al. as published in British Medical Journal (1)
These conclusions are completely overstated and, surprisingly, of a very different tone than the actual article.
In general, the study was well-designed and the authors provide evidence to support the inclusion of nutritionally-sound, commercial weight-loss programs in health care professionals’ referral repertoire. But the evidence does not support the claim that one-on-one counselling is “ineffective” especially if lead by RDs, arguably the most qualified nutritional professionals.
The Trial Basics
Study design and P-I-C-O: An eight-arm randomized controlled trial (RCT).
- P – overweight or obese adults volunteered to participate after GP approval. Program completers = 658, 1 year follow-up = 522
- I – 12-week weight loss interventions – commercial programs or primary care
- Weight Watchers: group-based healthy eating point system with weekly weigh in and social support. 60 minutes weekly
- Slimming World: group-based model including social support, low energy dense foods, and physical activity. 90 minutes weekly
- Rosemary Conley: group-based program includes social support, calorie counting, and weekly built-in physical activity component. 90 minutes weekly with 45 minutes optional physical activity
- Size Down Programme: dietetics-trained community led group sessions. 2 hours weekly x 6 weeks with two follow-up sessions
- Twelve one-on-one counselling sessions provided by a nurse in a primary care setting. 30 minute assessment, 15 – 20 minute follow-up
- Twelve one-on-one counselling sessions provided by a pharmacist: 30 minute assessment, 15 – 20 minute follow-up
- Choice: participant able to choose one of the interventions described above
- C – free vouchers for fitness club use
- O – weight loss at 3 months and 1 year
Risk of Bias and Limitations
Obvious strengths of the Lighten Up trial include the large sample size and duration of follow-up: 1 year post-intervention is quite rare in many clinical studies. The study investigators actually do a good job outlining the limitations of the study. Here are some of the major concerns identified.
- Lack of blinding. It would be impossible to blind participants. The concern here is the possibility of preconceived bias regarding likelihood of success (i.e., my friend loved Weight Watchers) or failure (i.e., Rosemary Conley did not work for my aunt) which may influence results.
- Where were the dietitians in this? Not sure about the UK, but there is a growing group of RDs working in Primary Care Networks (PCNs) in Canada. While better than nothing, the three-day training the dietitians provided to the nurses and pharmacists is NOT comparable to the education and professional experience of RDs, or even the facilitation experience within the commercial programs.
- Difference in convenience. Commercial programs were able to choose start date and location; whereas, the other groups were at the mercy of location, waitlists and clinic schedules. As a result, ~ 50% of one-on-one participants attended fewer than 4 sessions.
- Was counselling time adequate? Time allowed for one-on-one consultations seems a bit meager. Of particular concern, a 30-minute assessment does not provide a lot of time for rapport building, which could be partly responsible for attrition in one-on-one groups.
- Self-report is problematic. When participants declined study weigh-in at follow-ups, their self reported weight was used. No other indices of body composition or fatness, such as waist circumference were used.
- Is this a true control group? Technically speaking, providing free gym passes is not standard care nor a true control. This is evident as the control group’s activity levels increased, resulting in significant weight loss at 3 months.
The Major Findings
- ALL groups (including control) achieved statistically significant weight loss at 3 months, but significance did not persist at one year in primary care groups. Mean weight loss ranged from: 1.4 to 4.4 kg at 3 months and 0.7 to 3.5 kg at 1 year.
- Greatest degree of weight loss difference was in Weight Watchers group (when compared to control)
- After one year, 14 – 31% of participants had lost 5% of body weight.
No Baloney’s conclusions. Research continues to suggest that commercial weight-loss programs, such as Weight Watchers, are successful in promoting weight loss (there is a great discussion of the evidence in Jolly et al.). The fact that 31% of Weight Watchers participants were able to lose 5% or more of their baseline body weight may seem minor, but even just preventing ongoing weight gain is a success! Five percent is the current standard for “success” in a weight loss intervention and minimum cut off for an effective pharmaceutical treatment.
That being said, the authors’ conclusions in the abstract are overstated and misleading. While statements are made regarding the superiority of commercial programs to primary care interventions (particularly throughout the media reports), the study investigators admit that they were not adequately powered (i.e. sample size was not big enough) to make comparisons between groups, only to compare against the control group. Therefore, any comparison or statement suggesting that commercial weight loss programs are better than anything other than the control group is UNFOUNDED.
Does this mean that our current system of one-on-one counselling for weight loss and diet change is perfect? Absolutely not! As Jolly et al. (1) discuss, the research evidence for successful dietitian (and other health professional)-led interventions is not terribly convincing. Though what we know to be true in practice may be very different from what occurs in the quasi-realistic world of research studies, this should still be food for thought in terms of ongoing professional growth and development. There is still much to learn about what works for clients and how we as professionals can best promote self-efficacy and success in weight loss.
In terms of future directions for research, we still do not have any insight into what made the commercial weight loss programs successful. While the Lighten Up trial included some “open-ended feedback”, it was only briefly reported on. A qualitative component (i.e., focus groups) could have contextualized what was working in the commercial programs, especially Weight Watchers, that may have been lacking in the other interventions. 1) Was the group format and built-in social support network important? 2) Do people prefer to receive information from peers or former program member rather than health professionals? If yes, why and how can we change? 3) Was convenience with respect to location and time the major player in attrition vs. success? These are just a few possibilities that come to mind. We encourage you to suggest others in the comments section below.
Sixty percent of Canadians are overweight or obese (2) and an estimated 38% of men / 55% of women report they are trying to lose weight (3) – that translates to roughly 5 million men and 7.8 million women that are trying to lose weight in Canada; certainly more than all dietitians (and other professionals) combined could provide a 12-week ongoing weight-loss intervention to. Elucidating the characteristics and preferences of clients would be of tremendous help in targeting and referring individuals to the type of intervention most likely to meet their needs.
- Jolly K, Lewis A, Beach J, Denley J, Peymayne A, Deeks JJ, Daley A, Aveyard P. Comparison of range of commercial or primary care led weight reductions programmes with minimal intervention control for weight loss in obesity: Lighten Up randomized controlled trial. BMJ 2011; 343: epub ahead of print.
- Canadian Community Health Survey. 2004
- Kruger J, Yore MM, Kohl HW. Physical activity levels and weight control status by body mass index, among adults – National Health and Nutrition Examination Survey 1999–2004. Int J Behav Nutr Phys Activ 2008, 5: 25.