Every now and then we see articles about how bad "high fat" diets are for rats. Now, the obvious fact is that rats aren't humans. But that answer doesn't fly with everyone.
That's why I wanted to link to a study showing that truly high fat diets - high enough to put the rats into ketosis - don't have the effect that the merely moderately high fat diets do. This study looked at four rat diets rather than just two:
"Rat chow": A diet of standard lab rat food, 16.7% fat, 26.8% protein, 56.4% carbohydrate (6.5% sucrose)
"High fat": 45% fat, 24% protein, 35% carbohydrate (17% sucrose) - yes, it's high in sucrose as well as fat, but this is what the other studies have been using
"Ketogenic": 95% fat, 0% carbohydrate (0% sucrose), 5% protein
Caloric restriction: like the rat chow diet, but only 0.65 times as much, plus some extra nutrients so that it is only calories that are restricted
The caloric intakes on the three unrestricted diets were nearly identical, but the results were quite different. For example, the rats fed "high fat" got significantly fatter than any of the others. Meanwhile, the rats on ketogenic diets lost weight, ending up as thin as the calorie restricted rats. Insulin and leptin levels were high in the "high fat" rats, but the levels in the other three categories of rats were comparable with each other.
http://ajpendo.physiology.org/content/292/6/E1724.fullIt would be interesting if someone ran a longer term test of all four of these diets, to see the effects on lifetime. The caloricallly restricted rats would no doubt survive longer, as they always do, and I wouldn't be surprised if the "high fat" rats died sooner, but I'd be interested to see how the ketogenic diet compared to standard rat chow for rats.
