Not sure if this is the right place to post this (sorry if it isn't).

A couple of times per week my partner works long intensive shifts and will only get a break to eat around 6pm for 20 minutes. Where he works the only available kitchen equipment is a microwave.

He's just started a 16/8 eating pattern and is thinking of making these intensive days his true fast days with just one bigger meal later in the day.

Does anyone have any ideas for what he can take with him that is calorie dense and requires little to no prep?

He works with the public so can't snack.