Joey Chestnut -- the man who gobbled 72 wieners and buns on July 4th -- says he still feels like crap ... even after taking one.

Chestnut and Miki Sudo -- who won the women’s title in Nathan’s Famous Fourth of July Hot Dog Eating Contest -- were out in NYC Wednesday morning ... still paying a painful price for their gastronomical feats.

Joey says he gained roughly 23 pounds during the competition (15 pounds of hot dog, 8 pounds of water) ... and informed us the evacuation process had begun.

He doesn't expect to return to normal weight for at least a couple more days.

But get this, Chestnut tells TMZ Sports he's not 100% sure he'll return to competition next year after winning his 10th mustard yellow belt.

"If I come back, I'm gonna come back healthier," Chestnut says.