Method is explained here: https://macrocodex.app/knowledge/rethink/adaptive-tdee/

The actual method used in the app is a bit more complex than this, but I think this explanation is good enough to convey the core idea for now. Later, I plan to publish a more detailed write up.

>Also, how much better it is? How do we even know it’s better?

Very simple! If a car salesman tells you that they use space technology in the engine to improve fuel efficiency, how do you know whether they are telling the truth?

You fill the tank with a specific amount of fuel and drive. If the fuel lasts much longer, you know the technology is actually improving efficiency.

The same idea applies to MacroCodex.

When you eat at maintenance you do not gain weight, when you eat above maintenance you gain weight, when you eat below it, you lose weight.

If you set a goal in the app to gain 1 lb per week and consistently eat the calorie target prescribed by the app, then your actual weight gain should match that rate. If it does, you know the maintenance calories calculated by the app are accurate.

You can choose to set "maintain" or "lose" or "gain".