How Accurate Is AI at Calculating Macros?
By Francesco Zen, the coach behind Mr Z Updated
Quick answer
The arithmetic is rarely the problem. AI macro numbers go wrong on the inputs: total weight used instead of lean mass, a guessed body-fat figure, an activity level that sounds better than the real one, and a target nobody recalculates. Mr Z's macro logic is built around longevity and sustainability.
Where AI macro numbers go wrong
Ask a general AI chatbot for your macros and it will do the sums correctly. What decides whether the answer is any use is what it was given to work with, and what it assumes when it was not told.
- Total bodyweight as the basis. Most calculators, and most AI answers, start from total weight, which overstates protein for anyone carrying meaningful body fat. Lean mass is the better basis.
- A guessed body-fat figure. A self-estimate that is off by five or ten points shifts the lean mass figure enough to move every number after it.
- An optimistic activity level. A generic activity multiplier applied to a hopeful description of your week inflates the calorie target before any goal is applied.