FitDIY

Engineering notes

How FitDIY is built: no backend, no data collection — which makes some problems much more interesting.

Running Gemma on an iPhone to identify dinner

July 2026

FitDIY's privacy label ruled out sending meal photos to a server, so the food scanner had to run a 2.6 GB vision-language model entirely on-device. The eval said no. A takeout tray said maybe. Here's the whole story — failed benchmarks, Jetsam kills, and why CPU beat the GPU.