1 C1 informal
To gain weight or cause something to become larger or heavier.
"The bears fat up on berries and fish before hibernation begins."
separable
fat up
C1 informal separable transitive/intransitive
A non-standard, informal variant of 'fatten up' — to gain weight or to make something heavier or more substantial.
In plain English
To get fatter or make something bigger. Not a standard expression — most people say 'fatten up.'
What does "fat up" mean?
2 meanings, ordered from most common to least. Color-coded by CEFR level.
2 C1 informal
(Cooking, informal) To add fat or richness to a dish to improve its flavour or texture.
"Fat up the sauce with a spoonful of butter just before serving."
separable
Literal vs figurative
Words literally mean
To make fat — transparent and literal.
Actually means
To get fatter or make something bigger. Not a standard expression — most people say 'fatten up.'
Usage tip
Non-standard and uncommon. Heard occasionally in regional or dialectal speech. ESL learners should use 'fatten up' instead. May also appear in cooking contexts meaning to add fat or richness to a dish.
Words that pair with "fat up"
Natural word combinations native speakers use most often.
dish sauce livestock recipe winter
How to conjugate "fat up"
The five tense forms you'll use most often.
Base
fat up
I/you/we/they
3rd person
fats up
he/she/it
Past simple
fated up
yesterday
Past participle
fated up
have + pp
-ing form
fating up
continuous
Hear "fat up" in the wild
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Other ways to say "fat up"
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