What Is Emma Navarro's Chronic Illness? Health Issues and Weight Gain Explained After Cruel US Open Comments

Emma Navarro has battled her way into the US Open quarter-finals after months of health struggles, but the American tennis star's impressive comeback has been accompanied by cruel online comments targeting her body.

Navarro, 25, has faced remarks about her appearance and alleged weight gain during the tournament, including posts that surfaced around her opening-round victory over Lois Boisson. The criticism comes after it was reported during Wimbledon that Navarro has hypothyroidism, a chronic condition that can cause weight gain and fatigue.

The 26th seed has nevertheless produced some of her strongest tennis of the year at Flushing Meadows, beating Anna Kalinskaya 6-4, 6-2 in the fourth round to set up an all-American quarter-final against Jessica Pegula. It is Navarro's first Grand Slam quarter-final since the 2025 Australian Open.

What Is Emma Navarro's Chronic Illness?

Navarro's health condition was publicly identified as hypothyroidism during ESPN's coverage of Wimbledon in July, when presenter Chris McKendry discussed the American's diagnosis.

Hypothyroidism occurs when the thyroid gland does not produce enough thyroid hormones. Because these hormones help regulate the body's metabolism, an underactive thyroid can lead to symptoms including tiredness and weight gain.

The condition is generally long-term and can usually be managed with treatment. Navarro has not publicly detailed her treatment plan, so claims about how she is specifically managing the condition should not be assumed.

Emma Navarro's Health Issues and Weight Gain

Navarro's diagnosis provides important context as online users scrutinise her appearance during the US Open.

One X user attacked Navarro's weight during her first-round encounter with Boisson and continued making derogatory remarks even after another user pointed to her medical condition.

Hypothyroidism can contribute to weight gain, but that does not establish the cause of any perceived changes in Navarro's body. Navarro herself has not publicly attributed a specific amount of weight gain to her diagnosis.

The online reaction is not entirely new. Reporting following her return to competition in May noted that Navarro had already been subjected to unkind social media commentary about changes in her appearance.

Health Struggles Forced Navarro Away From Tennis

Navarro's health issues had a significant impact on her 2026 season before her resurgence in New York.

She stepped away from the tour earlier this year and missed both the Miami Open and her hometown Charleston Open. The break lasted roughly two months before she returned to competition and captured the Strasbourg title in May.

Speaking at the French Open following her return, Navarro acknowledged that the demands of professional tennis had aggravated her health struggles.

'Definitely exacerbated by playing tennis,' Navarro told journalist Ben Rothenberg. 'The tour is tough, and it'll take it out of you. It's constant travel and a lot of stress on the body and the mind.'

Emma Navarro's US Open Comeback Continues

Navarro has responded on court with one of her best Grand Slam performances since returning.

After surviving a three-set battle against Boisson in the opening round, she defeated fellow American Caty McNally before upsetting seventh seed Karolina Muchova 6-3, 7-5. She then dispatched Kalinskaya in straight sets to reach the last eight.

Navarro now faces world No. 3 Pegula for a place in the US Open semi-finals. Pegula has won all four of their previous meetings, including their encounter in Cincinnati last month.

For Navarro, the quarter-final represents another significant stage in a comeback season that was interrupted for months by health problems, while putting her within two victories of her first Grand Slam final.