To assess the impact of a National Enhanced Service (NES) incentive for weight management that financially rewarded practices for each eligible patient referred to a weight management programme.

Interrupted time-series analysis to examine the rate of weight management referral and weight management advice.

Primary healthcare records from January 2018 to December 2024 in the Oxford Clinical Informatics Digital Hub, covering 8.3 million patients in 1198 primary care clinics around England.

NES payments to practices for weight management were introduced in April 2021.

The rate of referral increased from 1 referral per 1000 patients per month before the incentive to around 4 referrals per 1000 patients per month afterwards. There was no evidence that the increase differed by age, gender, ethnic group or socioeconomic status. The occurrence of weight management advice was unchanged by the introduction of the NES and was at least three times more common than referral to weight management services.

The NES was associated with a fourfold increase in referrals to weight management services. However, clinicians are much more likely to offer advice rather than a referral to a weight management programme. There is a clear opportunity to improve outcomes for patients by encouraging greater use of referrals to effective weight management services in place of advice.