Mr Z
Is a General AI Chatbot Good for Fitness Advice?
Francesco Zen, founder of ZTraining · Last updated 19 June 2026
A real example: more than double the protein needed
What happened
What happened A client doing strength training and CrossFit, where protein should be set for performance, not pure muscle growth, used a general AI chatbot to build a diet. The result of the over-correction wasn't extra muscle. It was bloating, increased body fat, higher food spend, and unnecessary load on his liver and kidneys.
This is the pattern worth understanding: the advice wasn't wrong because a general AI chatbot made an error in its reasoning. It was wrong because nobody asked the one question that would have changed the entire calculation: what's your actual body composition, and what is this protein target for?
Why this keeps happening
A generic model answers the question you asked, not the question you should have been asked. "Help me build a diet" gets a diet.
What changes with a method-based AI
Related: Can a general AI chatbot build a real workout plan? · A general AI chatbot vs a real coaching method for fat loss
He built Mr Z, an AI coach trained on his methodology to bring the same approach to a wider audience.