Indian-origin NASA astronaut Sunita Williams, currently aboard the International Space Station (ISS) for an extended mission, has addressed growing concerns about her health. Recently released images of the astronaut showing a notably “gaunt” appearance sparked rumors about her deteriorating condition.

In response, Williams dismissed these rumors, explaining that her changed appearance was due to “fluid shifts” commonly experienced by astronauts in space. She clarified that the fluid redistribution in the body in a weightless environment causes the head to appear larger, and the body to look thinner, a phenomenon that affects many astronauts during long stays in space.

Williams, who has been seen with a thinner physique and sunken cheeks, reassured the public that she is in good health. Speaking on the New England Sports Network Clubhouse Kids Show, she explained the body’s fluid redistribution: “Folks in space, you know, their heads look a little bit bigger because the fluid evens out along the body.”

NASA has studied this “fluid shift” phenomenon extensively. Astronauts’ bodies naturally experience fluid movement upwards in space, increasing pressure in the head and affecting the visual system, as highlighted in NASA’s Fluid Shifts study. However, Williams countered any suggestions of health issues by stating she had actually gained muscle during her time in space, joking, “My thighs are a little bit bigger, my butt is a little bit bigger. We do a lot of squats.”

Despite some concerns voiced by an unnamed NASA source suggesting significant weight loss, Williams maintained that she was in good health, and NASA has confirmed that all astronauts aboard the ISS undergo regular medical evaluations and are monitored closely. Williams and her mission partner, Barry Wilmore, are expected to remain aboard the ISS until their scheduled return in February 2025, following a delay due to a failed Boeing Starliner mission. They will return to Earth aboard a SpaceX Crew Dragon capsule.