Forty-three RCTs were included in the review: one was rated excellent for methodological quality, 11 were rated good, 11 were rated fair and 20 were rated poor.
Workplace interventions that targeted physical activity and dietary behaviour reduced body weight significantly (WMD -1.19kg, 95% CI -1.64 to -0.74, Ι²=71%; nine RCTs, 4,514 participants), BMI (WMD -0.34kg/m², 95% CI -0.46 to -0.22, Ι²=59%; 11 RCTs, 4,638 participants) and body fat percentage calculated from sum of skin folds (WMD -1.12%, 95% CI -1.86 to -0.38, Ι²=43%; three RCTs, 368 participants).
Low-quality evidence on workplace interventions that targeted physical activity alone reported significant reductions in body weight (WMD -1.08kg, 95% CI -1.79 to -0.36, Ι²=0%; five RCTs, 283 participants) and BMI (WMD -0.5kg/m², 95% CI -0.65 to -0.34, Ι²=0%).
None of the RCTs targeted dietary behaviour alone.
Where available, effects on percentage body fat calculated from bioelectrical impedance or hydrostatic weighing, waist circumference, sum of skin-folds and waist-hip ratio were presented. Subgroup analyses showed a greater reduction in body weight for physical activity and diet interventions that contained an environmental component.