Fat makes you fat, and obesity causes diabetes. Everyone knows that, right?
But maybe Everyone is wrong.
Not everyone who is obese gets diabetes. To get type 2 diabetes, you need to have "diabetes genes" that won't let your pancreas increase in mass when you eat more carbohydrate, and usually eating more food means eating more carbohydrate, especially in today's fat-phobic world.
Now a German study in mice has found that in mice with a genetic susceptibility to diabetes, a high-fat, carbohydrate-free diet actually protects the mice from getting the disease.
The mice on the high-fat diets did gain weight faster than the mice on the control diet. A strain of lean mice on the same high-fat diets gained more weight than control mice, but not enough to be considered obese, yet-another proof that some animals (and some humans) can eat a lot and never get obese.
However, although the mice eating the high-fat, carbohydrate-free diet got fatter than the other mice, their diabetes rates were lower.
This is an example of correlation vs cause. The high-fat diet caused obesity, but the obesity didn't cause diabetes. It was carbohydrate that was causing the diabetes, probably by killing beta cells that had a genetic tendency to be stressed.
What does all this mean for you? That's difficult to say. Humans don't always react the same way as mice. And a totally carbohydrate-free diet would be extremely difficult to stick to in the long term. Even the Atkins induction diet allows some carbohydrate in foods like lettuce.
But it does suggest that the current dogma that fat is the villian and we should eat less fat and more carbohydrate may be causing the very disease we're trying to prevent. For more details about this study, see here.