Verbseoul.
regular
살찌다saljjidato get fat, to gain weight, to put on weight

To say to get fat, to gain weight, to put on weight politely in the present tense, use 살쪄요 (sahl-jjyuh-yoh). Below is the full conjugation of 살찌다 across the three tenses and three everyday speech levels.

Conjugation table

TenseCasual (반말)Polite (요)Formal (합니다)
Present
살쪄
sahl-jjyuh
살쪄요
sahl-jjyuh-yoh
살찝니다
sahl-jjeem-nee-dah
Past
살쪘어
sahl-jjyuh-ssuh
살쪘어요
sahl-jjyuh-ssuh-yoh
살쪘습니다
sahl-jjyuh-sseum-nee-dah
Future
살찔 거야
sahl-jjeel- -guh-yah
살찔 거예요
sahl-jjeel- -guh-yae-yoh
살찔 겁니다
sahl-jjeel- -guhm-nee-dah

Other useful forms

Command Polite (세요)
살찌세요
sahl-jjee-sae-yoh
Suggestion / Let's Polite (요)
살쪄요
sahl-jjyuh-yoh
Question Polite (요)
살쪄요?
sahl-jjyuh-yoh-?
Connective “and” — (고)
살찌고
sahl-jjee-goh
Conditional “if” — (면)
살찌면
sahl-jjee-myuhn
Noun form — (기)
살찜
sahl-jjeem