>No one is holding a gun to your head, forcing you to eat too much.

How you recognize what "enough," "too little," and "too much" are are based on a complicated set of hormonal and nervous system cues. When that system tips too far one way or another you're inevitably going to start gaining weight or have trouble building muscle.

The effect of commenting dismissively like this on a complex and emotional issue is that of trolling. We need you to be more thoughtful and to please resist flamebait like the guidelines ask.

https://news.ycombinator.com/newsguidelines.html

If you read the link, you will note she was athletic before the transplant, and became obese afterwards despite maintaining the exact same lifestyle.