Protein-sparing modified fast in the treatment of severe obesity: weight loss and nitrogen balance data.

Nitrogen balance has been measured in 25 (16 f, 9m) patients with severe obesity submitted for four weeks to total fasting (TF) or different versions of protein-sparing modified fast (PSMF). The hospitalized patients, divided into four age-matched groups, were treated as follows:Group 1, were submitted to TF; Group 2 were treated by 80 kcal-PSMF (17 g protein=2.6 g N, traces of fat and carbohydrate); Group 3 were submitted to 180 kcal-PSMF (40 g protein = 6.4 g N, 2 g fat, traces carbohydrate) and Group IV, to 80/180 kcal-PSMF (80 kcal during the 1st and 2nd week and 180 kcal during the 3rd and 4th week of treatment). Weight loss was similar (-11 kg) in Gps 1, 2 and 4; lower (-8 kg) in Gp 3. Mean daily Nitrogen loss was significantly lower (P < 0.05) in Gps 3 and 4 than in Gps 1 and 2. Nitrogen loss was significantly reduced from the 3rd week onward in Gps 1 (P < 0.005), 2 (P < 0.05) and 4 (P < 0.002). During 180 kcal-PSMF nitrogen loss was significantly lower (P < 0.005) only when this dietary regimen was preceded by 80 kcal-PSMF for two weeks (Gp 4). These observations suggest a new approach to the treatment of severe obesity by PSMF and show that is is possible to further reduce the early catabolic phase which commonly arises during this type of therapy.