This can be used to gain or lose weight. You simply need to eat above your maintenance calorie line to gain weight and below it to lose weight. No ads, no subscriptions, no payments, 16k users already.
If you're interested in how it works: https://macrocodex.app/knowledge/rethink/adaptive-tdee/
If anyone is interested, here's a writeup how we've built it: https://pluno.ai/blog/how-we-accidentally-built-a-faster-bro...
Re-posting the same question just creates noise.