Noun
Any substance that increases the ability of the body to metabolize a specific class of compound (such as fat).
One who metabolizes.
Source: en.wiktionary.orgI have been married to the same man for 44 years and I had no idea sex would be more thrilling at 70 than it was at 25! Also genetics, I have a genetic anomaly in my liver and am a fast metabolizer of estradiol. Source: Internet
For me, I found out I am a fast metabolizer of coffee. Source: Internet