Background In most developed countries socioeconomic disadvantage is associated with higher rates of obesity.  However, it is not known whether current interventions to prevent obesity are equally effective among all socioeconomic groups. If interventions are more effective in higher socioeconomic groups, they may lead to further widening of inequalities in obesity

Aims This review aims to determine whether obesity prevention interventions have equal effectiveness across all socioeconomic groups.

Methods A systematic search was conducted.  We included English language studies that described an obesity prevention intervention and reported anthropometric outcomes according to a measure of SEP. Evidence was synthesised using narrative analysis.

Results: The search identified3,634 articles, among which 14 studies were included in the final review. There was a range of study designs and methodological quality.  Nine studies were conducted among children. We grouped studies according to their potential impact on socioeconomic inequalities in obesity. 

Interventions with a greater effect among higher SEP compared to lower SEP participants included: family counselling; group-based exercise programs; school-based healthy-lifestyle curricula; school vending-machine restrictions, raised community awareness of healthy lifestyle; and a national mass media campaign.

Studies with a lesser effect among higher SEP compared to lower SEP participants included:  a TV allowance device in the family home; healthy school meals and activities; a kindergarten education program; school nutrition policies and local community changes such as healthy oils in take-away food outlets; free access to sporting facilities; and a community-wide strategy incorporating a large number of diet and activity interventions.

Conclusions Interventions that included a structural or environmental component were generally less likely to widen social gradients in obesity compared to those more focused on information delivery.  Interventions targeting individual-level behaviour change may be less effective in lower SEP groups, and could lead to a widening of socioeconomic inequalities in obesity.