Looks like you need to brush up on medical physiology. It's not as cut and dry as calories in/calories out.

You could eat 2500 calories of mostly fat and protein a day and potentially lose weight and actually gain weight even if you ate only 1200-1500 calories on a high carb diet (especially if you followed bad diet advice of eating more frequent smaller meals throughout the day).

INSULIN IS A HORMONE ASSOCIATED WITH ENERGY ABUNDANCE

As we discuss insulin in the next few pages, it will become apparent that insulin secretion is associated with energy abundance. That is, when a person’s diet includes a great abundance of foods that provide energy, especially excess amounts of carbohydrates, insulin secretion increases. In turn, the insulin plays an important role in storing the excess energy. In the case of excess carbohydrates, it causes them to be stored as glycogen, mainly in the liver and muscles. Furthermore, all the excess carbohydrates that cannot be stored as glycogen are converted under the stimulus of insulin into fats and stored in adipose tissue. In the case of proteins, insulin has a direct effect in promoting amino acid uptake by cells and conversion of these amino acids into protein. In addition, it inhibits breakdown of proteins that are already in the cells.

Guyton and Hall Textbook of Medical Physiology, Page 973

A lot of people have no idea how to eat well and working out doesn't do anything to help you lose weight if you're not eating properly. Reducing insulin spikes and reducing carbohydrate consumption is the key, which is why keto works so well for weight loss for so many, even if they're eating complete garbage AKA dirty keto.