You know when you eat food and drink drinks? Well, every one of those foods and every one of those drinks contain calories. Say it with me... calories. The reason I'm mentioning calories to you as though you are 5 years old is because the answer to the almighty "how to lose weight" question all revolves around calories. Not only does everything you eat and drink contain calories, but everything you do burns calories. Literally every step you take and every move you make burns calories. In fact, your body actually burns hundreds and even thousands of calories each day on its own just functioning. You could sit still all day and your body would still burn calories.
So now you may be wondering, if everything you eat contains calories, and everything you do burns calories, shouldn't they just cancel each other out? Yes, they should... and they do. If you consume the exact same number of calories that your body burns each day, your weight would stay exactly the same. If your body naturally burns 3000 calories a day, and you happen to eat 3000 calories a day, your weight would not change. In this example, 3000 calories is what's known as a calorie maintenance level. It's the number of calories required for the body to maintain its current weight.
I should probably have you repeat "calorie maintenance level" with me, because if there's one thing more important than calories when it comes to losing weight... it's your calorie maintenance level.