Paige Spiranac -- the most followed golfer on Instagram -- says she was forced to delete a ton of comments on her latest IG video ... after a bunch of men called her fat.
Spiranac posted the clip to her social media page on Wednesday -- showing her hitting a golf ball while wearing a tight, pink one-piece outfit.
The problem ... she said after she threw the footage online, men left hateful comments all over it.
"Honestly the amount of men calling me 'fat' on this post is next level lol," the 29-year-old pro-golfer-turned-influencer said to her 3.6 million followers on Wednesday night. "I've had to delete so many comments which I almost never do."
Spiranac says it was all troubling for her ... because she's struggled to "maintain my ideal weight all the time for year after year."
She said she works out and diets right, "but it doesn't come naturally to me."
She then urged the trolls to calm down on the vitriol going forward.