Only around half of patients took parts in weight programmes following referrals.
Patients in the East Riding, too obese for surgery, are being encouraged by their GPs to take responsibility for their own health, by changing their lifestyle.
Almost 500 patients were referred by clinicians, on to a six-month weight management programme in the last year, but only around half actually took part.
The scheme also targets smokers, in the aim to improve patients' health before they are referred for non-urgent surgery - such as a knee or hip replacement.
Dr Anne Jeffreys, from the East Riding Clinical Commissioning Group, she says: "The numbers have been slightly fewer than we expected, however, we know that some of the patients have accessed other weight management schemes, such as Slimming World or WeightWatchers, but because they're not monitored we don't know the exact numbers".