I think is important to know that the rate at which you burn carbohydrates increases with the intensity of the effort. If you keep the effort low enough, your body will use primarily fat for fuel and you will never run out of that. Keep hydrated and the pace low and you won't need any carbs supplements.
As you start pushing for hills or speed and the heart rate increases, you will start burning more and more carbs for fuel and there's a very limited supply of those (glycogen), maybe enough to last for 1-2 hours. Once you run out of carbs, you hit the wall and will slow down to the point where the body can run on fat alone.
You will need refuelling on route for longer rides at higher intensity. Bear in mind that after eating jelly babies or any other carb supplement, will be a certain delay until the carbs get digested and get into the blood stream, hence the advice of eating before hitting the wall to make sure you stay in the game.
For loosing weight, you need to be very honest about how many carbs you are eating during your rides as it is quite easy to overestimate the amount of calories you eat to effectively cancel out any benefits. It is perfectly possible to accumulate fat while cycling