Recently an individual inquired some advice on how to lose some fat. After stating to them what I thought would be the optimal process to achieve their goal, they told me that they were just simply going to eat less instead.
In trying to further explain the benefits of proper training and nutrition in order to optimize body chemistry an analogy came to mind. If your goal is to lose fat and you are currently unable, then you must fix the root problem.
Think of your body as a car. If the transmission on your car is broken, you cannot then fix the car simply by giving it less fuel. The body is no different. If you are unable to lose weight, then this means your body chemistry is damaged. The goal should be to fix what is damaged just like you would with that broken transmission. Simply eating less or giving your car less gas does nothing to address the issue of the transmission.
Metabolism is even far more complex than the mechanics of a car, so when dealing with goals pertaining to health/nutrition and fitness remember to think systemically in determining what choices will positively affect your goals.