For the body to function it needs energy which it gets from combustion. As with any machine, the body also needs raw material (food, oxygen, water) to be able to create energy from their combustion.
The body can get energy via two regimes of combustion:
- Carbohydrate-burning regime (promotes fat building)
- Fat-burning regime (promotes fat loss)
As it is with cars that can run both on diesel and gasoline, in which the gasoline-combustion regime is transferred to diesel combustion by the push of a button, so it is with the body. The button that transfers the body into carb-burning mode is insulin. And another hormone, called glucagon, is the button that transfers the body into the fat-burning mode.
The intake of protein triggers glucagon release. Carbs trigger insulin release. Fats alone don’t trigger either.
When the body burns carbohydrates, the ability to burn fat is lost. This doesn’t change even if you have protein along with the carbs. Then the excess carbs are converted into fats and are stored for “future needs”. If you continually feed carbs into your system, you then don’t allow your body to burn off the fat reserves. This way it relies on the “fresh” carb-fuel for energy and so doesn’t have the necessity to burn the stored fat. Thus there is no fat loss. Plus, the excess of this fuel will be stored as new body fat.
As the body is an adaptive mechanism, if it has much body fat, it will tend to keep itself in a fat-storing mode (if you don’t impose on it different conditions to which it will have to adapt).
For example, you eat a meal with 250 grams of steak, no addition of carbs (no bread, potatoes, etc.), and some green salad with olive oil. This meal will not trigger much insulin and so no amount of fats will be stored. These are very appropriate conditions that will boost secretion of the hormones which actually trigger muscle growth and fat-burning weight loss.
Now imagine what would’ve happened if you ate a carbohydrate dessert with no fats but with the same amount of calories as the steak meal. Your insulin level will spike to take away the sugars from the dessert. Insulin is the hormone that builds and stores fat. So the most of this sugar will not be burned out. It will be converted to fat and stored as body fat.
Eating dietary fat with the carbs slows down the digestion of carbs and their breakdown. The insulin response would be slowed down but we explain this combination from a theoretical aspect to demonstrate the way carbs work. This combination is not recommended as the carbs will still trigger insulin. And insulin will be too happy to collect everything on its way – broken down sugars and especially raw fats. But nevertheless it is the broken down carbs (blood sugar) that trigger insulin. Fats don’t.