The effect of whey and soy protein concentrates, skimmed milk powder as well as their combination on body weight, serum lipid profile, kidney and liver functions, leptin and thyroid hormones levels was investigated in obese rats. Thirty six adult male albino rats were divided into two main groups, the first main group (6 rats) was fed on basal diet and served as the control negative group, while the second main group (30 rats) was fed on high fat diet for four weeks to induce obesity then was divided into five subgroups, as follow: subgroup (1) was fed on high fat diet and served as the control positive group, subgroups (2, 3 and 4) were fed on high fat diet containing 30% protein from whey protein concentrate (WPC), skimmed milk powder (SMP) and soy protein concentrate (SPC), respectively and subgroup (5) was fed on high fat diet containing 30% protein from mixture (WPC, SMP and SPC) at equal ratios. The resultsindicated that supplementation with WPC, SPC, SMP and/or their mixture significantly decreased (P≤0.05) the elevated body weight of obese rats compared with the control positive group. Moreover, serum cholesterol, triglycerides, LDL-c, VLDL-c, urea, creatinine, uric acid, ALP, ALT and AST, leptin hormone and TSH concentrations were significantly decreased (P≤0.05) in all treated groups, while serum HDL-c, FT₃ and FT₄ were significantly increased (P≤0.05) compared with the control positive group. The obtained results suggest that supplementing with WPC, SPC, SMP and their mixture may cause favorable effects in body weight reduction as well as improving serum lipid profile, liver and kidney functions, leptin and thyroid hormones in obese rats.