Even when rats eat fewer calories, a keto-like diet can still cause unhealthy changes in the liver, like making too much sugar and having trouble breaking down proteins.

Even when rats eat fewer calories, a keto-like diet can still cause liver problems — like making too much sugar and messing up how the body uses protein — so the weight loss might not be worth the harm.

In rats, eating a diet super high in fat and very low in carbs for a month leads to higher blood sugar and more fat in the liver—even if they're not eating too many calories.

Rats on a very low-carb, high-fat diet for a month ended up with higher blood sugar and more fat in their livers—even if they didn’t eat more calories. This kind of diet might not be great for liver and blood sugar health in animals.

In rats, eating a diet high in fat and low in carbs changes how the liver handles certain fuels — it makes more sugar from lactate but gets worse at using alanine, especially when fewer calories are eaten.

Older male rats that had eaten a fattening diet did better with blood sugar and gained less weight when they ate 30% fewer calories for five weeks — showing that cutting calories can still help, even after bad eating habits.