Secret to keep weight off after very-low-energy diet is to switch back to normal food: Sahlgrenska Academy

Simple advice can reduce the risk of weight regain after a very-low-energy diet: the secret to keeping the weight off is to switch back to normal food gradually, reveals a dissertation from the Sahlgrenska Academy, at the University of Gothenburg, Sweden, which also contains new research results for patients who have undergone obesity surgery.

For 12 weeks a group of just over 260 patients swapped their normal food for a very-low-energy diet in the form of soups and milkshakes. 169 of the patients lost a lot of weight, averaging 16 per cent of their body weight. They were then divided into two groups so that they could switch back at different rates from the very-low-energy diet to energy reduced portions of normal food. One group completed the refeeding in a week, while the other took six weeks.

"After ten months the patients with the six-week refeeding period had gained 4 per cent in weight from their minimum weight, while the patients with the one-week refeeding period had gained eight per cent," says Lena Gripeteg, researcher at the Sahlgrenska Academy.

Very-low-energy diets have been used for many years in the health service to achieve rapid and safe weight loss in obese patients. While this treatment method is well-studied, there is a risk that patients will gain weight when they start to eat normal food again.

"We therefore want to look at the importance of different treatment advice on the transition from the very-low-energy diet back to normal food, and assess what actually works," says Gripeteg. "A simple tip that seems to work for patients is to revert slowly to normal food after losing weight on a very-low-energy diet."

Her dissertation also includes research results from the current national SOS (Swedish Obese Subjects) study, which has followed 2,010 patients who have undergone surgical treatment for obesity and 2,037 matched control patients for up to 20 years. It shows that men who have undergone obesity surgery are less likely to need a disability pension, while obese women are just as likely to need a disability pension whether they lose weight or not.

"On the basis of this study, we can't explain why there is a difference in the sexes," says Gripeteg. "It may well be that the underlying health problems differ between women and men, which could explain why there is a significant improvement in the ability to work in men, but no effect in women after surgical obesity treatment."