NASA astronaut Sunita Williams, who initially set out for a brief eight-day mission, now faces significant health challenges after an unexpected six-month stay aboard the International Space Station (ISS). A malfunction with Boeing’s Starliner spacecraft left Williams and fellow astronaut Barry Wilmore stranded, with their return to Earth postponed until Elon Musk's Dragon capsule arrives in February.

Visible weight loss sparks health concerns

Recent photos of Williams have raised concerns about her health, showing a visibly thinner and more gaunt appearance. Dr. Vinay Gupta, a pulmonologist from Seattle, noted that her sunken cheeks and thin frame suggest she may be losing more calories than she consumes—a risk during prolonged space missions.

In a latest photo, Williams is seen enjoying pizza and snacks, yet Dr. Gupta suggests that she could still be in a calorie deficit, possibly burning more calories than she can eat.

Nutritional deficiencies and muscle loss in space

Long missions in space place extra strain on the human body. Without Earth’s gravity, astronauts must work out for about 2.5 hours daily to counteract muscle and bone loss.

The cold environment of space further increases the body's energy demands, leaving astronauts like Williams and Wilmore at risk of nutritional deficiencies. Dr. Gupta suspects Williams’s body may be burning more energy as it adapts to weightlessness and maintains warmth in the harsh space environment.

Health risks for female astronauts

NASA research from 2014 found that female astronauts experience greater blood plasma loss and face higher metabolic demands than male astronauts, which may be adding to Williams’s physical stress.

A recent study from Ball University also indicated that women lose muscle faster than men in microgravity, meaning Williams could be at risk of severe muscle loss due to her extended stay.

NASA maintains crew is safe

Despite public concerns, NASA has reassured that Williams and Wilmore remain in stable health aboard the ISS.