A diet which replaces food with soups and shakes can help obese people achieve significant sustained weight loss, new research suggests.
UK patients with a BMI over 30, who ate just 810 calories per day, lost an average of almost 24lb (11kg) in one year, according to a study published in journal BMJ.
The researchers, from the University of Oxford, suggest total diet replacement programmes should be recommended by doctors and could ease pressure on GPs treating obesity-related illness.
The trial involved 278 obese adults in Oxfordshire, who were split into two groups.
The first were enrolled on a GP weight management programme, receiving advice and support from a practice nurse.
The second were offered a low-energy total diet replacement plan for 24 weeks.
Participants on the programme, provided by Cambridge Weight Plan UK, reduced their intake to 810 calories a day using specially designed soups, shakes and bars, and also took supplements.
They were given these products for eight weeks, before gradually re-introducing normal food, and also received diet counselling.
After 12 weeks on the programme, they were encouraged to continue replacing one meal a day with a replacement product.
The study found participants on the diet replacement plan lost an average of 23.6lb (10.7kg) after 12 months, 16lb (7.2kg) more than those on a GP practice programme.
They also had a greater reduced risk of developing heart disease, stroke and diabetes.
Almost half (45%) of obese people on the low-energy diet achieved weight loss of more than 10%, compared with just 15% of patients receiving help from their GP.
The study shows it is safe and effective for GPs to refer patients to total diet replacement programmes, the authors said.
Lead investigator Professor Susan Jebb, from the University of Oxford, said: “In the past we have worried that a short period of rapid weight loss may lead to rapid weight regain.
“But this study shows that nine months after the intensive weight-loss phase, people have lost more than three times as much weight as people following a conventional weight-loss programme.”
Dr Nerys Astbury, a senior researcher in diet and obesity at the University of Oxford, said: “This model of care, where patients are referred to a provider in the community for support, offers the potential for rapid roll-out at scale across the NHS and could help reduce the pressure on GPs in treating obesity-related disease.”
The study was funded by the Cambridge Weight Plan and the National Institute for Health Research.