Total diet replacement programs are not generally funded by the NHS in England but the authors of this study, published in the BMJ, suggest that there is now enough evidence for these programs to be one of the treatments recommended for people who are obese.

The randomized controlled trial involved 278 adults in Oxfordshire who were substantially overweight and interested in losing weight. Participants were either offered a referral to a low energy total diet replacement program for 24 weeks or were enrolled into their GP practice’s weight management program, including advice and support to lose weight from a practice nurse.

Participants on the total diet replacement program were asked to reduce their intake to 810 calories a day by replacing all food with specially formulated soups, shakes, and bars in addition to milk, water, and fiber supplements. These diet replacement products, which are designed to be nutritionally complete, were offered for 8 weeks, followed by a gradual re-introduction of conventional food over a further 4 weeks. Participants were invited to attend regular meetings with a trained counselor to develop techniques to help them follow the diet and later maintain their weight loss. From 12-24 weeks they were encouraged to continue to use one product a day to replace a usual meal.

After 12 months, these participants had lost on average 10.7 kg (1 stone, 9 lb), which was 7.2 kg (1 stone, 1 lb) more than those enrolled into the GP practice program. They also showed greater reductions in their risk of developing heart disease, stroke, and diabetes. Forty-five percent of participants on the low-energy program had achieved a weight loss of 10% or more compared with just 15% in the GP practice program.

The study’s chief investigator Professor Susan Jebb, professor of Diet and Population Health in Oxford University’s Nuffield Department of Primary Care Health Sciences, 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 9 months after the intensive weight loss phase, people have lost more than three times as much weight as people following a conventional weight loss program."

Co-investigator Professor Paul Aveyard, a GP and professor of Behavioural Medicine at the University of Oxford said: "Losing weight and keeping it off is hard, and we know that people welcome support from their GP. This study shows that GP referral to a total diet replacement program in the community is an effective intervention, which GPs can confidently recommend, knowing that it leads to sustainable weight loss and lowers the risk of heart disease and diabetes. This model of care can be safely offered by GPs in routine primary care."