Ketogenic diet is one of the most famous diets due to its ability to reduce weight quickly. With the high cost of healthy fats, there is a tendency to use more harmful fats in what is known as the dirty ketogenic diet. This study was conducted to evaluate the role of Bifidobacteria in reducing the potential negative effects of the ketogenic diet. Thirty-five experimental male albino rats were acclimated for two weeks and then divided into 5 equal groups. Groups were fed as follows: G1 negative control, a healthy balanced diet for 12 weeks; G2: positive control, ketogenic diet (3 fat: 1 protein) for 8 weeks and then a balanced diet for 4 weeks; G3, G4 and G5: fed as G2 plus 2 mL Bifidus milk inoculated with Bifidobacterium angulatum 2238, Bifidobacterium animalis subsp lactis BB12 and Bifidobacterium bifidum LMG 10645, respectively.

G2 showed a decrease in weight gain and an increase in liver index compared to G1. Rat groups fed with Bifidus milk (G3, G4 and G5) triggered an improvement in liver index. G4 showed significant recovery in liver enzymes, and antioxidant biomarkers, as well as lipid profile, and showed a lower atherogenic index. In conclusion, consumption of Bifidus milk during and after the ketogenic diet become a more secure way to apply this diet with low liver index, liver enzymes, and lipid profile.