This research investigated the effect of consumption of fermented kefir only or mixed with cereals (wheat, barley, maize and Mung bean) on nutritional and biochemical parameters on obese rats. Twenty albino male rats were classified into a negative control (five rats received the stander diet daily) and obese rats (received high fat diet 34% for 56 days). The obese rats were classified into three group, control (+ve) group and tow treated groups with kefir "4 ml/day/rat by stomach tube" and formula "20% of cereals mixed with 200ml kefir" for four weeks. The nutritional results revealed that Kefir and formula (cereals mixed with fermented kefir) administration suppressed the elevation of nutritional indicator of final body weight of obese rats. Biochemical results showed that rat group fed on kefir or formula had a significant improvement of lipid profile, atherogenic indexes and liver and kidney function values. Also these groups had significant lower value of leptin, glucose, insulin resistance, progesterone and malondialdehyde and higher values of insulin, superoxide dismutase, glutathione peroxides and testosterone compared with control (+ve) group. It is concluded that consumption of fermented kefir either separately or mixed with the most popular cereals have ability to manage over weight and could lower side effects of obesity so it is recommended to consume kefir and the examined formula in weight reduction strategies.