Basic:
fat | chubby | overweight | obese | (weight gain)

Expanded:
fat | chubby | overweight | obese | pudgy | robust | rotund | stout | plump | thick | thicc | tubby | lard | lardy | weighty | hefty | fatty | fattie | fatties | fatter | fats | fattest | heavyset | corpulent | chunky | chonky | chonk | chub | superchub | chubbier | blubber | blubbery | butterball | bulky | oversize | fatso | phat | poundage | round | belly | bellied | pudge | paunch | immobile | imobile | blob | fattening | obesity | morbidlyobese | morbidly_obese | weightgain | weight_gain | ("weight gain") | (weight gaining | gained) | growth | expand | expansion | BHM | SSBHM | BBW | SSBBW | fatfur | fat_fur | weightgainsequence | weightgain_sequence | weight_gain_sequence | wgsequence | wg_sequence -vore -voring -vored -diaper -diapers -inflation

No Muscle Overlap:
fat | chubby | overweight | obese | pudgy | rotund | plump | tubby | lard | lardy | fatty | fattie | fatties | fatter | fats | corpulent | chunky | chonky | chonk | chub | superchub | chubbier | blubber | blubbery | butterball | fatso | phat | poundage | pudge | paunch | immobile | imobile | fattening | obesity | weightgain | weight_gain | (weight gain | gaining) | BHM | SSBHM | BBW | SSBBW | fatfur | fat_fur | weightgainsequence | weightgain_sequence | weight_gain_sequence | wgsequence | wg_sequence -vore -voring -vored -diaper -diapers

WG:
aa -vore -voring -vored -diaper -diapers weightgain | weight_gain | wgsequence | wg_sequence | ("weight gain") | ("gain weight") | ("gaining weight") | ("gained weight") | ((fat | chubby | overweight | obese | pudgy | robust | rotund | stout | plump | thick | thicc | tubby | lard | lardy | weighty | hefty | fatty | fattie | fatties | fatter | fats | heavyset | corpulent | chunky | chonky | chonk | chub | superchub | chubbier | blubber | blubbery | butterball | bulky | oversize | fatso | phat | poundage | round | belly | bellied | pudge | paunch | immobile | imobile | fattening | obesity | weightgain | weight_gain | (weight gain | gaining) | growth | expand | expansion | BHM | SSBHM | BBW | SSBBW | fatfur | fat_fur) sequence | progression | progress | title part | pt1 | part1)

WG 2:
aa -vore -voring -vored -diaper -diapers weightgainsequence | weightgain_sequence | weight_gain_sequence | wgsequence | wg_sequence | ((fat | chubby | overweight | obese | pudgy | robust | rotund | stout | plump | thick | thicc | tubby | lard | lardy | weighty | hefty | fatty | fattie | fatties | fatter | fats | heavyset | corpulent | chunky | chonky | chonk | chub | superchub | chubbier | blubber | blubbery | butterball | bulky | oversize | fatso | phat | poundage | round | belly | bellied | pudge | paunch | immobile | imobile | fattening | obesity | weightgain | weight_gain | (weight gain | gaining) | growth | expand | expansion | BHM | SSBHM | BBW | SSBBW | fatfur | fat_fur) sequence | progression | title part | pt1 | part1)

WG 3:
aa -vore -voring -vored -diaper -diapers weightgainsequence | weightgain_sequence | weight_gain_sequence | wgsequence | wg_sequence | ((fat | overweight | obese | weightgain | weight_gain | (weight gain | gaining) | fatfur | fat_fur) sequence | progression | title part | pt1 | part1)

fat | obese | overweight (weightgainsequence | weightgain_sequence | weight_gain_sequence | wgsequence | wg_sequence | sequence | progression | title part | pt1 | part1)

Story:
me -vore -voring -vores -fart -farting -inflation weightgain | weight_gain | ("weight gain") | keywords fat | obese | overweight

Retire | retires | retired | retiring | retirement

koopa | koopa_troopa | koopatroopa | ("koopa troopa") | koopa_paratroopa | koopa_para_troopa | koopaparatroopa | ("koopa paratroopa") | ("koopa para troopa") | para_koopa | parakoopa | ("para koopa") | paratroopa | para_troopa | ("para troopa") | troopa | beachkoopa | beach_koopa | ("beach koopa")

Male:
fat | chubby | overweight | obese | pudgy | robust | rotund | stout | plump | thick | tubby | lard | lardy | weighty | hefty | fatty | fattie | fatties | fatter | fats | heavyset | corpulent | chunky | chonky | chonk | chub | superchub | blubber | blubbery | butterball | bulky | oversize | fatso | phat | poundage | round | belly | bellied | pudge | paunch | immobile | imobile | fattening | weightgain | weight_gain | weight | gain | gaining | growth | expand | expansion | BHM | SSBHM | fatfur | fat_fur

Pixiv Fat Tags:
Belly おなか
chubby でぶ
Fat furry デブケモ
bloated 太膨
fat デブ
gaining weight 肥満化
thick ふとましい
overweight 肉塊