Fats and carbs, two tanks, diet and exercise, and how it all hangs together

So, this is a bit of a brain dump about what I now think I understand about some of the basics of diet. It's taken me a long time to fit this together into a coherent whole, and so I suspect (possibly wrongly) that it's not obvious to others, but it looks to me to be critical basic information.

1. The body has two fuel tanks; one which stores fat, one which stores carbs.

2. You have about 70k kcal of fat, about 3k kcal of carbs.

3. When your carb tank is not full, and you eat carbs, it goes into the carb tank.

4. When your carb tank is full, and you eat carbs, it converts to fat and goes into the fat tank.

5. When the carb tank is empty, it's empty; you've hit the wall. Fats do not convert into carbs.

6. When you eat fat, it goes into the fat tank.

7. Digesting carbs is pretty demanding on the body, which is the same as saying as it ages you more quickly.

8. Each day, you burn about 2k kcal, just keeping alive. Most of this is from fat.

9. When you exercise, you're burning carbs. The 600 kcal you get through on the treadmill every hour are mostly carbs.

The upshot to my eye seems to be;

1. Eat carbs to replace those you use, no more.

2. Eat fat directly to replace the fat you burn just being alive.

3. If you want to lose weight, eat less fat than you burn just staying alive, and do not eat more carbs than you use (which is another way of saying do not eat carbs when the carb tank is full, as they turn into fat).

4. Loosing weight is mainly done by the body burning fat just staying alive. The main point of exercise is to keep a healthy body, which is the same as saying age more slowly, and to allow us to eat yummy carbs without turning them into fat :-)