If you're naturally thin it's because you have efficient fat cells. Fat goes in quickly and it comes out easily. Your body doesn't need much fat because the little bit of fat you do have is a reliable source of fuel.
If you are predisposed to be fat, it's because you have greedy fat cells. When you eat you tend to store calories as fat instead of burning them and when your other tissues need those calories, the fat comes out slowly if it comes out at all.
The end-user of the food that we eat are individual cells. It doesn't matter if it goes in our mouth, if your cells don't get it we start starving at the cellular level and so you do exactly what your body is telling you to do, YOU TEND TO EAT MORE! It means that you're not getting fat because you eat more, you're eating more because you're getting fat.
Most of us weren't born with greedy fat cells but we can certainly make them that way. Eating too much carbohydrates will raise your blood sugar level. Since high blood sugar is toxic, your body releases insulin to bring it down. But your body can only burn a little bit of sugar at a time. So, what happens to the rest of it. Your storage sites for carbohydrate are limited. We've got unlimited storage places for fat so the body just keeps converting the carbohydrate to fat and after bringing down your blood sugar your insulin does its other job. It will tell your body to STORE FAT!
When you have a healthy metabolism it only takes a little bit of insulin to start bringing your blood sugar level down and then everything goes back to normal but over time that can change. The cells can become resistant to the effects of this little insulin. In essence when that happens, insulin is talking but the cells are not listening and they don't get the message and they don't do what they're suppose to do and so your body does what it has to do. It starts producing more insulin before it reached a point where your insulin is high that use to keep your blood sugar low and you're not getting any sugar and when that happens it starts to drive stuff into the fat cells then YOU GET FAT!
