Gradual weight loss no better than rapid weight loss for long-term weight control

The study, led by Joseph Proietto, Sir Edward Dunlop Professor of Medicine at the University of Melbourne and Head of the Weight Control Clinic at Austin Health in Australia, set out to examine whether losing weight at a slow initial rate, as recommended by current guidelines worldwide, results in larger long-term weight reduction and less weight regain than losing weight at a faster initial rate in obese individuals.

The Australian trial included 200 obese adults (BMI 30-45kg/m²) who were randomly assigned to either a 12-week rapid weight loss (RWL) programme on a very-low-calorie diet (450-800 kcal/day) or a 36-week gradual weight-loss (GWL) programme. The GWL programme reduced participants' energy intake by approximately 500 kcal/day in line with current dietary weight loss guidelines. Participants who lost more than 12.5% of their bodyweight were then placed on a weight maintenance diet for 3 years.

Participants who lost weight faster were more likely to achieve target weight loss: 81% of participants in the RWL group lost ≥12.5% of their bodyweight versus just 50% in the GWL group. The researchers found that the initial rate of weight loss did not affect the amount or rate of weight regain in these patients who entered the subsequent weight maintenance period, as similar amounts of weight were regained after 3 years by participants who had lost weight on either diet programme. Weight regain was around 71% in both groups after 3 years.

According to Katrina Purcell, dietician and the first author on the paper from the University of Melbourne, "Across the world, guidelines recommend gradual weight loss for the treatment of obesity, reflecting the widely held belief that fast weight loss is more quickly regained. However, our results show that achieving a weight loss target of 12.5% is more likely, and drop-out is lower, if losing weight is done quickly."

The authors suggest a number of possible explanations for their findings. The limited carbohydrate intake of very-low-calorie diets might promote greater satiety, and less food intake by inducing ketosis. Losing weight quickly may also motivate participants to persist with their diet and achieve better results.

Writing in a linked Comment, Dr Corby Martin and Professor Kishore Gadde from Pennington Biomedical Research Center, Baton Rouge, USA say, "The study...indicates that for weight loss, a slow and steady approach does not win the race, and the myth that rapid weight loss is associated with rapid weight regain is no more true than Aesop's fable. Clinicians should bear in mind that different weight loss approaches might be suitable for different patients in the management of clinical obesity, and that efforts to curb the speed of initial weight loss might hinder their ultimate weight loss success.