Discussion
The findings of this systematic review suggest that worksite interventions are effective in improving some measures of dietary behaviour. Effect sizes are variable but are generally small, although decreases of up to 9% in total dietary fat and increases up 16% in daily fruit and vegetable intakes have been reported. However, worksite intervention research has typically been methodologically weak and many studies have not included appropriately matched control groups, meaning reported effects may be due to trial participation rather than the actual worksite intervention programme. The use of
self-reported dietary outcomes in most studies is a particular cause for concern because reporting bias due to dietary education makes it probable that effects on diet are over-estimated.
Our findings are fairly consistent with two recent systematic reviews of worksite weight loss interventions on body weight [11,12]. Benedict and Arterburn reviewed 11 intervention studies published between 1995 and 2006 and reported that intervention groups lost -0.2 to-6.4 kg more body weight than controls over follow-upperiods ranging from two to 18 months [12]. Anderson et al reviewed 47 intervention studies published between 1966 and 2005, and a meta-analysis of a sub-set of nine RCTs produced a pooled effect estimate of -2.8 pounds of weight loss (95% confidence interval -4.6, -1.0) over
6-12 months of follow-up [11]. Thus, it appears that worksite health promotion interventions also have positive effects on employee body weight but effect sizes are
small.