Gigi's rant comes after she recently strutted her stuff down the catwalk at New York Fashion Week, stunning onlookers with bright pink hair, a zipped up pink crop top that exposed her midriff and a silver skirt.
She complemented the look with the gown's pinstripe ruffle top and toughened up the all-black ensemble with a pair of light grey military-style boots.
Nevertheless, in her final post, Hadid stated she was unwilling to explain how her body looks to other people any longer, even though, ironically, she wrote a 1000-word essay on precisely that topic.
The 22-year-old addressed her 8.5 million Twitter followers on Sunday in multiple posts, particularly "those of you so determined to come up with why my body has changed over the years".
'.Not to judge others, but drugs are not my thing, stop putting me in that box just because u dont understand the way my body has matured (sic)'. In 2014 she revealed she had Hashimoto's disease, an autoimmune disease that gradually destroys the thyroid.
"Those of you who called me "too big for the industry" were seeing inflammation and water retention due to that".
Gigi said the changes to her body are down to her now being "properly medicated" to help symptoms which include "extreme fatigue and metabolism issues".
Model Gigi Hadid rehearses on the runway at Tommy Hilfiger Women's Spring 2016 during New York Fashion Week: The Shows at Pier 36 on September 14, 2015 in New York City. "I may be "too skinny" for u, honestly this skinny isn't what I want to be, but I feel healthier internally and am still learning and growing with my body everyday, as everyone is", she continued.
Gigi went on to explain what Hashimoto's disease is and how it affects a person's size. Moreover, she said that while some people might think she looks too skinny, she is actually feeling much better than ever before.
And she insisted she wasn't eating any less than she used to, it was that her "body just handles it differently now". "Use your energy to lift those that you admire rather than be cruel to those u don't".
The NHS says Hashimoto's thryroiditis can "take months or years" to be diagnosed and is "caused by the immune system attacking the thyroid gland, making it swell and become damaged".