Mackenzie Standifer is no stranger to criticism.

Unlike other stars in the Teen Mom galaxy, there was no heyday during which she was beloved by fans.

She entered the scene as the love interest, and later the wife, of Ryan Edwards.

Fans already weren't crazy about her, simply because they weren't crazy about Ryan.

And as Edwards' addiction issues worsened, Standifer was widely viewed as the worst sort of enabler.

For many Teen Mom fans, the first Mackenzie scene they vividly recall was the one in which Ryan passed out while driving to their wedding, and Mackenzie turned off the dash cam to save him some embarrassment.

Sadly, that dangerous interaction served as a preview -- or a warning sign -- of things to come.

In the years that followed, Ryan would be arrested several times on drug related charges.

Now, after multiple stints in rehab, it appears that Edwards is sober, but Teen Mom OG fans continue to regard him with suspicion.

No matter how many drug tests he passes, Ryan will always have something to prove.

And these days, it seems Mackenzie is under some of the same suspicions.

Standifer posted the above photo on Instagram this week.

No doubt she was proud of herself for slimming down following the birth of her second child.

Mackenzie probably thought she would be praised for her efforts, and some fans did congratulate her on finding a diet and exercise routine that clearly works for her.

But others were quick to heap hate on Ryan's wife, with at least one going so far as to accuse her of using the same drugs that nearly cost Edwards his life.

“That stuff that she says she is on would never give you a flat tummy after [having] a baby,” one such critic wrote, as reported by In Touch Weekly.

“The stuff that she is making is only to make money. Like Macy stated, she is a ‘fake.’ I personally think she is doing [husband Ryan Edwards’] drugs!!” 

Understandably irate, Mackenzie was quick to respond to the criticism.

“I’m not ‘on’ anything,” she replied.

“I eat right and work out. It’s not rocket science, and there’s no quick fix," she continued.

"I take supplements to SUPPLEMENT my diet, but nothing is a miracle fix.”

Being accused of using illicit drugs when your results are simply the result of diet and exercise would be frustrating under any circumstances.

But for Mackenzie, the remarks are especially hurtful, as she devoted years of her life to helping Ryan get clean.

The idea that she would endure all of that merely to experiment with the same substances -- and for the purposes of weight loss, no less -- must be revolting to Standifer.

And sadly, she's been putting up with this sort of bullying for her entire time in the spotlight.

Earlier this year, the abuse led Mackenzie to take an extended hiatus from social media.

“To be really honest, most of the comments on my pictures are ridiculously mean, especially about how I look and how much weight I gain and how ugly I am or how I’m a terrible mother/wife,” she explained in January.

“I really can’t ever win. I didn’t want to surround myself/deal with that while being pregnant.” 

Sadly, it's a feeling that many Instagram users can relate to.

View Slideshow: Maci Bookout to Mackenzie Standifer: STFU About My Drinking & Work on Your Train Wreck Husband!