The biggest quest in such application is data creation. I have used Fatun Chrome Extension which downloads images from google image search page for various food items.
Place food images in /data dir with food name folder as name and train with below command
$ python src/train.py
the weights get stored in 'weights' dir.
Run
$ cd src
$ python3 predict.py ../data/val/vadapav/images\ \(24\).jpg
and it will print food class name
Run flask webapp
$ cd src
$ export FLASK_APP=webapp/webapp.py
$ python3 -m flask run