As activist Sonam Wangchuk remains under close medical supervision after more than three weeks of fasting, doctors say his condition underscores the profound physiological stress that prolonged fasting can place on the human body. Research shows that going without food for extended periods can trigger major changes in metabolism, hormones, inflammation and electrolyte balance, with risks increasing the longer the fast continues.

Wangchuk, 59, has been on an indefinite fast since June 28 in support of students protesting alleged examination paper leaks and demanding the resignation of Union Education Minister Dharmendra Pradhan. By the time he was shifted from his protest site at Jantar Mantar to Safdarjung Hospital on Saturday, he had reportedly lost more than nine kilograms after surviving only on salt and water.

Authorities said the transfer became necessary after doctors warned that his condition had become medically risky, including concerns over dangerously low potassium levels. A health bulletin issued by Vardhman Mahavir Medical College and Safdarjung Hospital on Sunday (July 19) said his vital parameters were stable and some blood markers had shown minor improvement. However, doctors said he continued to require close monitoring because of the physiological stress associated with prolonged fasting.

According to the bulletin, treating teams from Safdarjung Hospital and AIIMS, New Delhi, said sustained medical intervention and round-the-clock clinical monitoring remained essential to detect and manage potential complications arising from the prolonged fast.

His hospitalisation has also triggered a legal and medical dispute. While the hospital said Wangchuk had declined intravenous fluids, oral rehydration solution and medicines despite repeated counselling, his wife, Gitanjali Angmo, questioned the hospital’s handling of his treatment and opposed any intervention without the family’s consent. The Delhi High Court, hearing the matter on Sunday, declined to order his discharge, noting that doctors considered continued monitoring necessary because of concerns over his deteriorating health.

What prolonged fasting does to the body

Scientific studies suggest that prolonged fasting sets off a cascade of physiological changes as the body adapts to the absence of food. While some of these changes are expected survival mechanisms, they can become medically significant when fasting continues for long periods.

The body shifts from glucose to fat

A 2025 study published in the journal Molecular Metabolism followed 20 middle-aged volunteers who underwent a medically supervised, water-only fast lasting nearly 10 days, followed by carefully supervised refeeding.

The researchers found that participants lost an average of 7.7 per cent of their body weight. Blood tests confirmed that their bodies had entered ketosis—a metabolic state in which the body switches from using glucose to burning stored fat for energy. This shift was reflected in rising levels of blood ketones, substances produced when fat becomes the body’s primary fuel.

Inflammation and liver stress increase

The same study found that prolonged fasting also altered several blood markers.

Levels of C-reactive protein (CRP)—a protein produced by the liver that rises during inflammation—increased sharply. Researchers also observed increases in markers of platelet activity and liver enzymes.

The study noted that “the acute inflammatory response during prolonged fasting may serve as a transient adaptive mechanism.”

Its findings were reinforced by observations from a separate group of 1,422 people undergoing modified fasting, in which two out of three participants showed increased CRP levels regardless of how long they fasted.

Hormones and blood chemistry change

A second study, published in Scientific Reports in 2025, examined 13 men in their late fifties who underwent an eight-day water-only fast, with some participants also exercising.

The researchers concluded that fasting had a greater impact than exercise, significantly altering blood sugar, growth hormone, cortisol and leptin levels.

Like the first study, it found that fasting pushed participants into ketosis. The researchers also cautioned that in people with liver disease, prolonged ketosis could progress to ketoacidosis, a dangerous buildup of acid in the blood.

Another notable finding was that uric acid levels more than doubled during the fast.

Together, the two studies showed that fasting lasting eight to ten days can produce measurable changes in metabolism, hormone levels, inflammation, liver function and blood chemistry.

Older adults face greater risks

The risks become greater with age, according to Dr Subrata Das, Lead Consultant and Head of Internal Medicine at Aster Whitefield Hospital.

“For older adults, if fasting goes on for a long time, it can be more dangerous physiologically, partly because muscle mass and what people call metabolic reserve—the body’s stored energy and ability to cope with physical stress—are already smaller as we age,” he said.

“A prolonged period of being without food may bring muscle weakness that doesn’t immediately go away, plus reduced immune response, nutritional gaps, worse bone stability, and even a slower return to regular physical functioning,” Dr Das said.

He added that prolonged fasting can also affect major organs.

“Depending on how much weight was lost and how intense the metabolic stress became, there can also be longer-term issues tied to cardiovascular fitness and kidney function, especially if dehydration showed up or there was an electrolyte imbalance,” he said.

Electrolyte imbalance refers to abnormal levels of minerals such as sodium, potassium and magnesium, which are essential for regulating heartbeat, nerve function and muscle activity.

The dangers don’t end when fasting stops

Recovery depends on several factors, including the duration of the fast, age, nutritional status and any underlying illnesses, Dr Das said.

He warned of refeeding syndrome, a potentially dangerous complication that can occur when food is reintroduced after prolonged starvation.

“Refeeding syndrome may result due to the abrupt introduction of nutrients, leading to quick changes in electrolyte levels such as phosphate, potassium and magnesium following prolonged periods of fasting,” he said.

He also said persistent ketone production can indicate that the body is under considerable stress.

“Urinary ketones indicate that the body has shifted into ketosis, where fat is being used as the primary fuel because glucose availability is inadequate,” he explained.

“Persistent or high ketone levels, particularly when accompanied by dehydration, electrolyte disturbances or worsening kidney function, suggest that the body’s energy reserves are under considerable strain.”

As Wangchuk remains under medical supervision, his case highlights the physiological consequences of prolonged fasting. While the body can adapt to food deprivation for a period by switching to alternative energy sources, doctors and research suggest that extended fasting places increasing stress on multiple organs and metabolic systems, making close medical monitoring essential as the fast continues.