abstemiously
adv. C1 Advanced ab·stemious·ly
adv. to eat or drink only a small amount, especially to stay healthy or follow a rule.
adv. to practice self-restraint in eating or drinking; to consume only what is necessary or permitted.
He abstemiously drank only water during the fast.
The monks lived abstemiously, consuming only the simplest of meals to focus on their spiritual work.
By living abstemiously and avoiding luxury, the family managed to save enough money to fund their children's education without taking on debt.
From abstemious + -ly.