Weight loss in 108 obese women on a diet supplying 800 kcal/d for 21 d.

A series of 108 obese women were studied for 21 d in a metabolic ward on a diet supplying 800 kcal/d (3.4 MJ/d), with 4.5 g protein nitrogen, 40% energy from fat, and 46% from carbohydrate. The average total weight loss was 5.0 kg. During the second and third week on the diet the rate of weight loss was 211 +/- 77 g/d (mean +/- SD) and individual values were well predicted by admission resting metabolic rate (RMR) (r = 0.66, p less than 0.0001). The calculated energy density of the weight lost in this phase was 7000 kcal/kg (29.3 MJ/kg). However, the weight loss in the first week had a labile component of 815 +/- 1202 g, which was not well predicted by RMR (r = 0.20, p less than 0.05). The effect of this labile component was to obscure the overall rate of weight loss so some of the patients did not show net weight loss until day 13 of the diet, although they were in negative energy balance.