IPA: /ˈdaɪ.ɪ.tɛr.ɪ.li/
KK: /daɪˈɛtərɪli/
In a way that relates to diet or the kinds of food that a person eats.
She chose to eat dietarily to improve her health.
Dietarily → It is formed from "diet" (from Old French *diete*, meaning a way of life or regimen) and "-arily" (meaning in a manner relating to). The word "dietarily" refers to something done in a manner relating to diet or dietary practices.
Think of 'diet' as a way of life and '-arily' meaning in a manner. This helps you remember that 'dietarily' refers to actions or practices related to one's diet.