One in four adults in the United Kingdom is overweight, so successful weight management programmes are urgently needed. With about 16% of the UK population and 28% of Americans seriously trying to lose weight,1 it is no wonder the commercial slimming industry is booming. Although their combined reach is hard to ascertain—Rosemary Conley alone claims more than 80 000 UK members and Weight Watchers 1.5 million worldwide members—commercial companies have their part to play. To date, evidence of the success of commercial approaches is limited.2 It could be argued that either a lot of people are trying to lose weight unsuccessfully or that without the contribution of the commercial sector the obesity crisis would be worse. Either way, the linked trial (Lighten Up) reported by Jolly and colleagues (doi:10.1136/bmj.d6500) is a welcome addition to the evidence base.3

Lighten Up was designed to test the relative effectiveness of weight management services provided by general practices, pharmacies (NHS), and commercial companies compared with a self directed exercise comparator group.4 The BBC’s Diet Trials is the only other non-commercially funded study conducted in the UK to have examined the relative efficacy of commercial weight loss programmes, …