http://www.ncbi.nlm.nih.gov/pubmed/3661473

Full paper at http://ajcn.nutrition.org/content/46/4/557.full.pdf

Young, healthy, 24 BMI males. Lost 3.7 kg body weight in a 3 day fast.

Resting metabolic rate reduced by 5.7 kcal/h (137 kcal/day) and fat oxidation increased by 0.6 g/h to 5.7 g/h (137 g/day). RMR after 3 day fast was 1630 kcal/day. Carb oxidation reduced 50%, protein oxidation non-significant reduction.

Glucose production down 63% after 3 days compared to overnight fast.