Rapid weight loss schedule better than received wisdom of gradual weight loss

A randomised clinical trial presented at the European Congress on Obesity 2026 has suggested that rapid weight loss can deliver greater one-year weight reduction than a gradual approach

A structured rapid weight loss programme has achieved greater one-year weight reduction than a gradual weight loss approach in adults with obesity, according to research presented at the European Congress on Obesity 2026 in Istanbul, Turkey.

The investigator-initiated randomised clinical trial team was led by Dr Line Kristin Johnson, of the department of endocrinology, obesity and nutrition at Vestfold Hospital Trust in Tønsberg, Norway. It is a collaborating centre of the European Association for the Study of Obesity which organises the congress and leads obesity advocacy and education activities in Europe.

The findings challenge the long-standing belief that rapid weight loss is inherently less healthy than slower weight reduction, or that it necessarily increases the likelihood of subsequent weight regain – so-called ‘yo-yo dieting’. The authors noted that such concerns have largely rested on observational evidence, historical assumptions or small studies with methodological limitations, rather than on robust randomised controlled trial data.

The study compared a rapid weight loss programme with a gradual weight loss programme in relation to sustained weight loss and the achievement of clinically meaningful treatment targets. The investigators used body mass index and waist-to-height ratio thresholds identified in recent population-based research as potential indicators of reduced long-term risk of obesity-related complications, including type 2 diabetes, hypertension, atherosclerotic cardiovascular disease and hip or knee osteoarthritis.

A total of 284 adults with obesity, defined as a body mass index of at least 30 kg/m², were enrolled in the 52-week trial. Of these participants, 257 were women, equivalent to 90 per cent of the study cohort. Participants were randomly assigned in equal numbers to either a 16-week food-based rapid weight loss programme or a 16-week food-based gradual weight loss programme.

The rapid weight loss programme restricted daily energy intake to less than 1,000 kcal during weeks 1 to 8, less than 1,300 kcal during weeks 9 to 12 and less than 1,500 kcal during weeks 13 to 16. The gradual weight loss programme used a daily energy deficit of 800 to 1,000 kcal below estimated total energy expenditure, with participants in this group reporting a mean intake of approximately 1,400 kcal per day.

After the initial 16-week weight loss phase, both groups entered an identical 36-week weight-regain prevention programme. Participants attended weekly in-person group sessions during the first 16 weeks. They then had in-person group meetings every 14 days for the first three months of maintenance, followed by monthly meetings or individual contact through webinars, video consultations or telephone calls during the final five months.

Dietary advice in both programmes reflected current Norwegian recommendations, with emphasis on vegetables, fruit, whole grains, low-fat dairy products, fish, eggs, lean meat and other protein-rich foods, while saturated fats and added sugars were limited.

During the initial 16 weeks, participants in the rapid weight loss group lost significantly more body weight than those in the gradual weight loss group. Mean total body weight loss was 12.9 per cent in the rapid group and 8.1 per cent in the gradual group – meaning that the rapid loss group cut their weight by 59.3 per cent more than the gradual cohort.

The difference remained significant at one year. Mean total body weight loss reached 14.4 per cent in the rapid weight loss group and 10.5 per cent in the gradual weight loss group – here the rapid loss group achieved a total weight reduction of 37.1 per cent more than the gradual cohort.

The rapid weight loss group also had higher proportions of participants to reach predefined body mass index and waist-to-height ratio targets. At one year, 28.3 per cent of the rapid weight loss group reached a body mass index of 27 kg/m² or less, compared with 9.7 per cent of the gradual weight loss group. For waist-to-height ratio, 33.0 per cent of the rapid weight loss group reached a ratio of 0.53 or less at one year, compared with 18.4 per cent of the gradual group.

“Among adults with obesity, participation in a structured rapid weight loss programme resulted in significantly greater weight loss at one year, and higher rates of achieving clinically meaningful body mass index and waist-to-height ratio targets compared with a gradual weight loss approach,” the authors concluded.

These findings indicate that, when provided within a controlled and professionally supervised setting, rapid weight loss may represent a more effective method than gradual weight loss for reaching key body weight targets associated with reduced obesity-related health risks.

“Our results clearly challenge the prevailing belief that slow and steady gradual weight loss is necessary to prevent weight regain and reduce obesity-related complications,” Johnson said.

“By contrast, we show that rapid weight loss [does not have to be] associated with weight regain, and, more importantly, that a larger proportion of participants undergoing rapid weight loss – compared with gradual weight loss – achieved clinically meaningful treatment targets for reducing the 10-year risk of type 2 diabetes, hypertension, atherosclerotic cardiovascular disease and hip or knee osteoarthritis.”

The results suggest that rapid weight loss, when delivered through a structured food-based programme with professional supervision and a defined maintenance phase, may be a viable option for some adults with obesity.

For further reading please visit: 10.1002/osp4.70094