Researchers at Glasgow University evaluated the success and costs of the Counterweight Plus programme, developed by seven UK universities, which is aimed at people with a BMI greater than 40 and available from GPs.
They looked at results from 22 general practices in Scotland where 91 severely obese patients were put on the programme which incorporates Cambridge Weight Plan diet, with users placed on an 810 calorie per day liquid diet of shakes and soups with food reintroduced at specific points of the programme.
The study found the results came close to those achieved by surgery, with almost all patients losing weight – up to 40kg in some cases. Average losses of 17kg were recorded after 14 weeks with at least one-third (33%) of the 91 dieters maintaining a loss of more than 15kg – or two stone – for 12 months.
Further analysis, published in the British Journal of General Practice, found each £1 million spent on Counterweight Plus would result in about 360 severely obese patients losing more than 15 kg, compared with only about 105 patients if the same £1m were spent on proving lap-band surgery.
Professor Mike Lean, a human nutrition expert in the School of Medicine, said: "This amount of weight loss is enough to reverse most cases of type 2 diabetes and approached the levels achieved by lap-band surgery, but is much cheaper and safer than surgery. It is also much more accessible. Weight loss surgery is only available for a tiny number of patients, and requires a great deal of training and back-up."
The Cambridge plan replaced food with nutritionally complete, low-calorie drinks and gave fast results, although critics say it is too extreme and can provoke health problems. It was developed in the 1960s at Cambridge University by Dr Alan Howard. The diet was re-launched in 1984 as the Cambridge Weight Plan.
The ethos, participants have said, is to put your body in a state called ketosis – a state in which you are undernourished and your body must process your fat stores in order to survive.