After Boeing’s Starliner spacecraft left them stranded on the International Space Station in June, Sunita “Suni” Williams and Barry “Butch” Wilmore are facing several more months in space before they can return home.
Williams and Wilmore, who were only supposed to spend around a week in space, will return to Earth in February aboard the Crew-9 mission Dragon capsule that brought NASA astronaut Nick Hague and Roscosmos cosmonaut Aleksandr Gorbunov to the station in late September.
While the stranded astronauts have adapted to their extended stay in space, there are some concerns about their health after spending so long in zero gravity.
Recent images of the astronauts raised concerns about Williams’ weight loss, with pulmonologist Vinay Gupta telling the Daily Mail that the astronaut appears to have dropped below a healthy body weight.
“What you’re seeing (…) is somebody that I think is experiencing the natural stresses of living at a very high altitude, even in a pressurized cabin, for extended periods,” Gupta said. “Her cheeks appear a bit sunken—and usually it happens when you’ve had sort of total body weight loss.”
How Has Sunita Williams Responded to Health Concerns?
“I think there’s some rumors around outside there that I’m losing weight,” Williams said in a video interview from the ISS on November 12, in response to a question from the New England Sports Network.
“I’m the same weight that I was when I got up here,” she said.
In fact, Williams noted that she is gaining muscle from all the weightlifting that astronauts do on board the ISS.
“I could definitely tell that weightlifting, which is not something that I do all the time, has definitely changed me. My thighs are a little bit bigger, my butt is a little bit bigger,” Williams said.
NASA officials also responded to the health concerns, stating that all astronauts aboard the ISS were in good health.
“All NASA astronauts aboard the International Space Station undergo routine medical evaluations, have dedicated flight surgeons monitoring them, and are in good health,” NASA spokesperson Jimi Russell told Newsweek.
Gupta had suggested that Williams’ apparent weight loss may be due to her not consuming as many calories as she is burning. Astronauts are usually encouraged to eat as many as 3,500 calories per day due to the increased energy requirements of living in space, combined with the hours of exercise astronauts do every day. To get their calorie intake up, astronauts eat a high-calorie diet rich in meat.
“Your metabolism [in space] fundamentally requires you to burn way more energy than you’re intaking, even if you’re intaking pepperoni slices,” Gupta said. “Her body’s probably working harder to do basic things, because the partial pressure of oxygen is lower than it would be on sea level.”
Astronauts face a large number of other health risks during their stay in space. In a weightless environment, muscles aren’t used as much, which can lead to them weakening and atrophying. Additionally, the lack of gravity causes bones to lose minerals at a faster rate, leading to bone density loss.
“Astronauts experience accelerated bone loss at an alarming rate—about 12 times faster than severe osteoporosis on Earth,” Kyle Zagrodzky, founder and CEO of bone health clinic OsteoStrong, previously told Newsweek. “This rapid deterioration occurs because bones no longer bear the constant gravity load in space. As a result, density and strength diminish quickly, compressing years of potential osteoporosis into mere months.”
“Osteoporosis increases fracture risk, often leading to life-altering injuries,” Zagrodzky said. “Hip fractures pose a grave concern, as they can strip away independence and increase mortality risk.”
Outside Earth’s atmosphere, astronauts are also exposed to much higher levels of cosmic and solar radiation, increasing their risk of cancer.
Several studies have found that the effects of spaceflight are more harsh on women’s bodies than men’s. One 2014 paper revealed that women lose more blood plasma than men in space, while another 2023 study found that women lose muscle at a faster rate.
However, Williams’ alleged weight loss may be due to other personal reasons, and likely has no effect whatsoever on her ability to perform her duties as an astronaut and ISS commander.
How Long Have the Starliner Astronauts Been in Space?
Williams—who is now in command of the ISS—and Wilmore have been on the ISS since June 6, arriving, at the time of writing, via the Boeing Starliner 160 days ago. They were supposed to head home after only eight days, but after the Starliner developed thruster troubles and helium leaks, the spacecraft was returned to Earth without them, leaving them aboard the ISS.
Williams and Wilmore will return to Earth alongside the Crew-9 astronauts, with two seats being left empty on the Dragon to accommodate the stranded pair. They will have been in space for around 250 days by the time they return in February 2025, but this is not the longest time an astronaut has been in space by far.
The record-holding American astronaut is Frank Rubio, who spent 371 days in space between 2022 and 2023, while the longest-ever spaceflight record is held by Russian cosmonaut Valeri Polyakov, who was in space for 437 days straight in the 1990s. NASA astronaut Christina Koch currently holds the record for the longest single spaceflight by a woman at 328 days.
Russian cosmonaut Oleg Kononenko, however, has spent the most time in space of any other person, with 1,111 days in space across five missions.