Most of energy consumption is baseline metabolism, which is directly correlated with your muscle mass.

The fastest and healthiest way to get a better body (which is not loosing weight) it is to start lifting heavy things over and over again.

You can starve yourself and loose wait, also rather fast, but as soon as you go back to your standard eating, that weight will come back.

If you increase your muscle mass, you won't necessarily loose weight, fat will be replaced by muscle, but your appearance will be much better, you will be healthier and overall you will just feel better.

As always there are not shortcuts.