Intermittent versus on-demand use of a very low calorie diet: a randomized 2-year clinical trial


H Lantz, M Peltonen, L Ågren, J S Torgerson, Department of Body Composition and Metabolism, Sahlgrenska Hospital, Gothenburg


Journal of Internal Medicine 2003; 253: 463-471

Patient group:

334 obese patients (BMI > 30 kg/m2) aged 18 - 60 years, of whom 86 were men. Initial average BMI was 38.7 kg/m2.


Obesity is a chronic disease which requires long-term treatment. Surgery has been shown to result in significant and lasting weight loss, but for various reasons surgery is not an option for most obese patients. Other methods are needed, but relatively few studies are available with treatment periods of more than three years.

VLCD is commonly used in obesity treatment and results in rapid and substantial weight loss. To maintain this weight loss, VLCD treatment is often followed by various strategies, such as hypocaloric diet, physical activity, behavior modification and/or intermittent use of VLCD. Studies of intermittent VLCD follow-up have been conducted for periods shorter than one year, but more long-term results are lacking. An alternative to intermittent therapy could also be to use VLCD as needed (on-demand) when a tendency to weight relapse is noted.


Patients were randomized into two groups, one for intermittent treatment and one for on-demand treatment. Both groups began with a 16-week course of VLCD (earlier formulation of Modifast). Over the following three weeks ordinary food was stepwise reintroduced and during the remaining period (up to 2 years) an individualized hypocaloric diet was recommended.

The intermittent group also repeated a pure VLCD regimen for two weeks every three months, while the on-demand group used VLCD as soon as their weight passed an individualized, predetermined limit.

Results and discussion:

After the initial VLCD period, patients in the intermittent group had lost an average of 20.6 kg, corresponding to 18.3%, while the on-demand group lost 22.0 kg, corresponding to 19.0% (p <0.001)

Two years after treatment start, those who completed treatment in both groups had lost an average of 7.0 kg, corresponding to 6.2% and 9.1 kg, corresponding to 7.7%, respectively. This weight loss was clearly significant (p < 0,001), but the difference between the groups was not. After two years, 44% of patients in the intermittent group and 62% of the on-demand group had maintained a greater than 5% weight loss (p = 0,054). The corresponding figures for weight loss of more than 10% after two years were 28% and 38%, respectively.

One significant difference that was observed was that men in the on-demand group lost significantly more weight than men in the intermittent group, 14.5 ± 11.0 kg compared with 4.0 ± 10.5 kg (p <.01).

Most risk factors for cardiovascular disease improved significantly during the first year. Anthropometric measurements, including insulin, HDL and LDL cholesterol, also improved somewhat after two years of treatment.


Clinically significant weight loss was achieved after two years of VLCD-based treatment. The structuring of follow-up treatment had no significant effect on weight loss in the study population as a whole, but men may benefit from an on-demand VLCD strategy.…