Do You Know What I Am?

Riddle: My life can be measured in hours, my serve is by being devoured. When my kind is thin we are quick, but when my kind is fat, we are slow. What am I?

Answer: I am a candle.

Source: https://www.riddles.com/9862

My life can be measured in hours, my serve is by being devoured. When my kind is thin we are quick, but when my kind is fat, we are slow. What am I? — Do you know what I am? by a human v1.

Riddle: My life can be measured in hours, my serve is by being devoured. When my kind is thin we are quick, but when my kind is fat, we are slow. What am I? Answer: I am a candle. — by a human v2.