[BlackJack]

Insulin does not cause the body to convert glucose into fat. That process is known as 'de novo lipogenesis', and Lyle is correct that it is very rare.

From a high level perspective, I agree that insulin causes the body to burn blood glucose for fuel. The extra "carbs" don't get magically converted to fat though - they're used to replenish muscle glycogen and perform other actions. It is the dietary fat ingested alongside carbohydrates that gets stored as fat in the body.

Here's a quick summary: http://examine.com/faq/how-are-carbohydrates-converted-into-....

Note: I am not an advocate of ketogenic or otherwise low carb diets. I think a calorie deficit and adequate protein intake is all that you need to lose fat. No diet can work without some sort of calorie deficit, either explicitly or indirectly induced.