Comparison of a low-energy diet and a very low-energy diet in sedentary obese individuals: a pragmatic randomized controlled trial

There is no consensus on whether 'very low-energy diets' (VLED; <800 kcal d(-1) ) cause greater weight loss in obese individuals than 'low-energy diets' (LED; 800-1200 kcal d(-1) ). The objective was to determine whether a very low-energy formula diet would cause greater weight loss than a formula 810 kcal d(-1) LED in older sedentary individuals. This is a pragmatic randomized controlled trial.

Inclusion criteria: obesity (body mass index [BMI] > 30); age >50 years, with knee osteoarthritis. Participants were randomized to VLED (420-554 kcal d(-1) ) or LED (810 kcal d(-1) ) for 8 weeks, followed by a fixed-energy (1200 kcal d(-1) ) diet with food and two diet products daily for 8 weeks. In all, 192 participants were randomized. Mean age was 63 years (standard deviation: 6), mean weight 103.2 kg (15.0) and BMI of 37.3 kg m(-2) (4.8) at baseline. Mean weight losses in VLED and LED groups were 11.4 kg (standard error: 0.5) and 10.7 kg (0.5) at week 8 and 13.3 kg (0.7) and 12.2 kg (0.6) at week 16. Mean differences between groups were 0.76 kg (95% confidence interval: -0.59 to 2.10; P = 0.27) and 1.08 kg (-0.66 to 2.81; P = 0.22) at 8 and 16 weeks, respectively. Loss of lean body mass was 2.1 kg (0.2) and 1.2 kg (0.4) (17% and 11% of the weight lost, respectively) at week 16 in the VLED and LED group with a mean difference of 0.85 kg (0.01 to 1.69; P = 0.047). Significant adverse effects comparing VLED and LED, were bad breath: 34 (35%) vs. 21 (22%), intolerance to cold: 39 (41%) vs. 17 (18%) and flatulence: 43 (45%) vs. 28 (29%) for VLED and LED at 8 weeks (P < 0.05 in all cases). The VLED and LED regimens were equally successful in inducing weight loss. The significantly lower loss of lean tissue in the LED group together with more frequently reported side effects in the VLED group, favours the choice of low-energy diet (LED) for the treatment of obesity.