expression
having a small appetite; eating only a little
Describes someone who habitually eats small amounts or has a naturally light appetite. Often used as a fixed expression.
See also: 食の細い
彼女は食が細いので、いつも少ししか食べない。
She has a small appetite, so she always eats only a little.
うちの子
My child has a small appetite and ends up leaving school lunch uneaten.