Weighing up the evidence: a systematic review of the effectiveness of workplace interventions to tackle socio-economic inequalities in obesity.

Background
Addressing socio-economic inequalities in obesity is a public health priority and the workplace is seen as a potential health promotion site. However, there is a lack of evidence on what works. This article systematically reviews studies of the effects of workplace interventions on socio-economic inequalities in obesity.

Methods
Following PRISMA guidelines, we searched for published or unpublished experimental and observational evaluation studies. Nine electronic databases were searched as well as websites and bibliographies. Included studies were data extracted, quality assessed and narratively synthesized.

Results
Eighteen studies were included of which 14 examined behavioural interventions and 4 mixed or environmental ones. While most studies (n = 12) found no effects on inequalities in obesity—and a minority found increases (n = 3), there was also some evidence of potentially effective workplace interventions (n = 3) especially in terms of physical activity interventions targeted at lower occupational groups.

Conclusion
There is experimental evidence that workplace delivered physical activity interventions have the potential to reduce inequalities in obesity by targeting lower occupational groups. However, overall, the evidence base is small, largely from the USA, and of a low quality. More high-quality, experimental study designs are required.