Eight studies (n=791) were included in the review.
The results for between-group differences in the text and tables differed. The values reported below were taken from the text.
Weight loss (5 studies, n=375, range: 39 to 104).
Two studies reported that Internet programmes were associated with significantly greater weight loss than control or usual care treatments: -2.2 versus +1.0 kg (p=0.002) and 1.63 versus +0.21 kg (p=0.003), respectively. Two studies reported that adding behaviour therapy or e-counselling to Internet programmes was associated with significantly greater weight loss than the Internet programmes alone: -4.4 versus -2.0 kg (p=0.04) and -4.0 versus -1.7 kg (p<0.001), respectively. One small study (n=46) comparing a commercial programme available via the Internet to a public 16-lesson step-by-step manual programme found that the manual programme group lost significantly more weight at 16 and 52 weeks than the Internet group: -3.3 versus -0.8 kg at 52 weeks (p=0.04).
Weight loss maintenance (3 studies, n=418, range: 46 to 250).
Two studies found no statistically significant differences in weight maintenance between Internet programmes and in-person or control groups. One study (n=122) found that the Internet group sustained a significantly lower weight loss than the minimal in-person or frequent in-person support group at the end of the 1-year maintenance period: -5.7 kg versus -10.4 kg versus -10.4 kg (p<0.5).