"I experienced [body-shaming] with my weight fluctuation for the first time," Gomez recalled, per Entertainment Tonight. "I have lupus and deal with kidney issues and high blood pressure, so I deal with a lot of health issues, and for me that's when I really started noticing more of the body image stuff."
The "Lose You to Love Me" singer explained that her weight changes aren't a direct result from lupus, but a "combination" of factors.
"It's the medication I have to take for the rest of my life -- it depends on even the month, to be honest," Gomez said. "So for me, I really noticed when people started attacking me for that. In reality, that's just my truth. I fluctuate. It depends what's happening in my life."
"That got to me big time," she said of the negative comments she received about her weight. "I think for me, that really messed me up for a bit."
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The former Disney star went on to express that she's now "very happy with living my life" and doesn't put as much stress on social media.
"I don't care to expose myself to everyone and hear what they have to say about it," she said, adding that she tries to live by the golden rule: "Treat other people the way you wish you were treated."
Gomez concluded by revealing her "biggest lesson."
"How to learn, [when it comes to] the people that have hurt me the most, to forgive them," she explained. "And to continue to understand and have compassion for people."
Gomez has been open with her health journey and revealed her lupus diagnosis in 2015. Lupus is an autoimmune disease that causes inflammation throughout the body and can be potentially life threatening.