BMJ  2006;332:1284-1285 (3 June), doi:10.1136/bmj.332.7553.1284

Editorial

The BBC diet trials

Reality television and academic researchers jointly tackle the weight loss industry

In 2000, 46% of women and 33% of men in the United States were trying to lose weight¹; they spent an estimated $34.7bn (£18.5bn; 27bn) on weight loss products and programmes.² Did they get their money's worth? Unfortunately, the answer is probably no. The prevalence of obesity increased from 30.5% to 32.2% between 1999 and 2004 in the United States,³ and expenditures on health care associated with excess body weight exceeded $56bn.⁴ Further, the Federal Trade Commission found four years ago that 40% of all advertisements for weight loss products made false or misleading claims.²

There has been little rigorous scientific research on the efficacy and safety of commercial products and programmes⁵—but in this week's BMJ Truby and colleagues report their findings from such a study (p 1309).⁶ Participants were recruited by national advertisements to take part in a reality TV series, BBC Diet Trials, that urged them to "be a star in your own right and lose weight."⁷ This was a multicentre randomised controlled trial in the United Kingdom of four widely available commercial programmes for weight loss. Participants were randomised to use for six months the Slim-Fast Plan, Weight Watchers Pure Points Programme, Dr Atkins' New Diet Revolution, Rosemary Conley's "Eat Yourself Slim" Diet and Fitness Plan, or to a control group receiving usual care, with all costs of the diet programmes and travel expenses covered by the BBC.

At six months, the four commercial programmes did not differ in their ability to promote weight loss and body fat loss (of about 6% and 3%), but all four programmes were superior to the control condition on those outcomes. Only Weight Watchers produced a statistically significant (albeit clinically small) reduction in plasma glucose and total cholesterol concentrations when compared with the control group. Consumers of commercial weight loss programmes value information on safety and costs highly.⁸ The study by Truby and colleagues did not report any serious adverse events, and the six month attrition rate (over a quarter of all participants) did not differ substantially in the diet groups.⁶ While the authors do not report the impact of these programmes on gastrointestinal symptoms, they do say that a greater proportion of participants did not tolerate the Atkins and Slim-Fast diets than the Weight Watchers and Rosemary Conley programmes.

A sobering finding from this study is the proportion of people who had continued their treatment assignment at 12 months—six months after the BBC stopped covering treatment costs. With more than half of the original population reporting at one year, only 15% of those assigned to the Atkins or Slim-Fast programmes were still using them, compared with 35% of those assigned to Rosemary Conley and Weight Watchers programmes. Beyond that, the low follow-up rate at one year in this study makes inference on long term effectiveness impossible. Finally, the costs of these programmes to the consumer are also notable. The Atkins book can be purchased for only £3, compared with 24 weeks of Rosemary Conley classes (£140), Weight Watchers classes (£170), and twice daily Slim-Fast meal replacements (£240).^{4 5}

Consumers can turn to the Partnership for Healthy Weight Management (www.consumer.gov/weightloss) for help in evaluating their commercial weight loss treatment options.⁴ As few commercial weight loss programmes have peer reviewed data to support their efficacy and safety claims, the greatest value in Truby and colleagues' study is its scientific rigour and its focus on four widely available programmes.

Given the seemingly endless stream of fad diets and miracle products for weight loss, academically affiliated researchers must, now more than ever, collaborate with industry partners to improve the evidence base for obesity treatment. Industry's fears about the potential for adverse publicity from "negative" studies should be assuaged by examining the case of Weight Watchers. This company began reporting data on the safety and efficacy of its programme in 2000, has become one of the most rigorously studied of all commercial programmes, and continued to show double digit revenue increases in 2005.^{5 8 9} There are numerous ways to lose weight in the short term. The challenge to researchers in obesity is to take weight loss studies, especially those involving commercial programmes and private funding, to the next level. "Diet Trials II" would serve us best by evaluating long term health outcomes, cost effectiveness, and novel strategies of improving adherence and weight maintenance. Such strategies might include economic incentives for participants and researchers collaborating with employers and healthcare providers. The BBC could also greatly serve the public by presenting data on efficacy, safety, and cost in their health related programming—thereby imposing some reality on "reality television."

Group Health Center for Health Studies,1730 Minor Avenue, Suite 1600, Seattle, WA 98101, USA
(arterburn.d{at}ghc.org)

---

Competing interests: None declared.

Research p 1309

References

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2. Cleland RL, Gross WC, Koss LD, Daynard M, Muoio KM. Weight-loss advertising: an analysis of current trends. Federal Trade Commission, 2002. www.ftc.gov/bcp/reports/weightloss.pdf (accessed 24 May 2002).
3. Ogden CL, Carroll MD, Curtin LR, McDowell MA, Tabak CJ, Flegal KM. Prevalence of overweight and obesity in the United States, 1999-2004. JAMA 2006;295: 1549-55.[Abstract/Free Full Text]
4. Arterburn DE, Maciejewski ML, Tsevat J. Impact of morbid obesity on medical expenditures in adults. Int J Obes Relat Metab Disord 2005;29: 334-9.[CrossRef][Medline]
5. Tsai AG, Wadden TA. Systematic review: an evaluation of major commercial weight loss programs in the United States. Ann Intern Med 2005;142: 56-66.[Abstract/Free Full Text]
6. Truby H, Baic S, deLooy A, Fox KR, Livingstone MBE, Logan CM, et al. Randomised controlled trial of four commercial weight loss programmes in the UK: initial findings from the BBC "diet trials". BMJ 2006;332: 1309-11.[Abstract/Free Full Text]
7. BBC Nottingham News. TV stardom—a weighty problem. 3 June 2002. www.bbc.co.uk/nottingham/spotlight/2002/06/diet_trials.shtml (accessed 24 May 2006).
8. Wang SS, Wadden TA, Womble LG, Nonas CA. What consumers want to know about commercial weight-loss programs: a pilot investigation. Obes Res 2003;11: 48-53.[ISI][Medline]
9. Weight Watchers International. Weight Watchers announces full-year 2005 results and initiates cash dividend. 16 February 2006. www.corporate-ir.net/ireye/ir_site.zhtml?ticker=WTW&script=410&layout=7&item_id=818480 (accessed 24 May 2006).

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Related Article

Randomised controlled trial of four commercial weight loss programmes in the UK: initial findings from the BBC "diet trials"

Helen Truby, Sue Baic, Anne deLooy, Kenneth R Fox, M Barbara E Livingstone, Catherine M Logan, Ian A Macdonald, Linda M Morgan, Moira A Taylor, and D Joe Millward
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