A woman in her 30s in China lost 20 kilograms through an extreme 15-day water-only fast, then was diagnosed with a brain disease marked by impaired walking and memory. The timing of the fast and the onset of symptoms lined up precisely with the cycle in which the body depletes its thiamine (vitamin B1) reserves.
According to StatPearls, a medical information database under the U.S. National Institutes of Health (NIH), when thiamine intake is restricted, the body's stores run out within two weeks, after which falling blood levels trigger Wernicke encephalopathy. Because thiamine is a water-soluble vitamin, the body stores little of it to begin with.
A 2007 study by Sechi and Serra described stores as being depleted in about 18 days, with lesions forming between two and three weeks in brain regions such as the mammillary bodies that consume large amounts of thiamine. Thiamine is an essential coenzyme in the Krebs cycle and the pentose phosphate pathway, through which the brain converts glucose into energy, so a deficiency leads directly to a failure of energy production in brain cells.
The prognosis is not mild. StatPearls put the mortality rate for Wernicke encephalopathy at 17%, with 80% of survivors progressing to Korsakoff syndrome, characterized by severe memory impairment. Autopsy studies have found a prevalence of 1% to 3% in the general population, while the rate of diagnosis during a patient's lifetime stands at around 20%.
Domestic academic circles also classify the disease as a neurological emergency that occurs when nutrition is cut off for an extended period — not only in alcohol use disorder but also in voluntary fasting, malabsorption and hyperemesis of pregnancy.
A case that followed exactly this path was recently confirmed in China. According to the Hong Kong-based South China Morning Post (SCMP) on the 25th, a 31-year-old woman surnamed A in Henan Province went to a hospital after 15 straight days of drinking only water left her struggling to walk and suffering memory loss.
A, who is 160 centimeters tall and weighed 70 kilograms before the fast, is said to have cut her weight to 50 kilograms in the span of about two weeks. Sun Guifang, a neurologist at the First Affiliated Hospital of Zhengzhou University, diagnosed A with Wernicke encephalopathy caused by a deficiency of vitamin B1 (thiamine). Sun said A walked with a waddling gait like a penguin and explained that this walking impairment may not fully recover.
A told the medical staff that she had practiced "bigu," a Taoist fasting method. The term means avoiding grains, and the practice stems from a belief that living on nothing but "qi" — the life energy that flows through the universe — leads to transcendence and immortality. It is believed to date back to before 221 B.C., during the Qin dynasty.
On one Chinese social media service, hashtags related to bigu have drawn 360 million views and 2.4 million related posts. Some users have posted accounts of losing more than 10 kilograms by consuming only water and vitamin supplements for a month, and some posts advise meditating in a well-ventilated place to take in qi.
Cases leading to health problems or death have recurred. In 2020, in Heilongjiang Province, a 26-year-old man died after fasting on water alone for 52 days. He is said to have shown dementia-like symptoms starting two days before his death. Last year, in Zhejiang Province, a woman ate only water and so-called "energy pills" and lost 5 kilograms in a week, but her intestinal mucosa was severely damaged, allowing bacteria to enter her bloodstream, and she experienced life-threatening hypokalemia.
Sun warned that "the human body must eat regularly to obtain essential nutrients" and that "excessive dieting and fasting can pose serious risks to health." For those who need to lose weight, the recommended approach is to focus on minimally processed foods, cut back on sugar and fat, and secure sufficient protein.
If dizziness, abnormal eye movements or an unsteady, off-balance gait appear during rapid weight loss, one should seek medical care immediately. Wernicke encephalopathy can be reversible if thiamine is administered early, but if the window is missed, memory damage becomes permanent.
