In recent years, “water fasting” has become one of the most popular trends among those seeking rapid weight loss. The concept is simple: complete abstinence from food and drinks except water for a period ranging from one to three days.

Many believe this fasting detoxifies the body, restores balance, and even helps regenerate cells, but the reality is more complex than it appears.

Water fasting may provide temporary relief and stimulate some beneficial processes, but it is not suitable as a long-term weight loss plan. The safe approach combines a balanced diet, moderate physical activity, and adequate sleep. The real goal is not only weight loss but improving overall health and maintaining body balance.

According to a report published on the vinmec website, reasons vary from person to person; some see it as a quick way to lose weight or to rest the digestive system. Although studies indicate some potential benefits, this type of fasting is not suitable for everyone, especially without medical supervision.

During fasting, the body begins to eliminate old or damaged cells and recycle their components, a biological process known as “autophagy.” Numerous animal studies confirm this process can protect against age-related diseases such as Alzheimer’s and cancer. It is also believed to help extend cell lifespan and improve efficiency.

Research conducted on people with high blood pressure showed that several days of water fasting — under medical supervision — lowered blood pressure to normal levels in most participants. In one study, more than 80% of participants achieved a healthy blood pressure rate after just two weeks of continuous fasting.

Insulin regulates blood sugar levels, while leptin helps with satiety. During fasting, cells become more responsive to these hormones, meaning better appetite control and metabolism regulation. This may contribute to faster and more stable short-term weight loss.

Other human trials observed decreased triglycerides and cholesterol levels after only one day of water fasting, positive indicators for heart health. Animal experiments also showed fasting reduces damage caused by free radicals, harmful molecules that accelerate aging and weaken immunity.

Although water fasting seems like a natural and simple method, incorrect or prolonged application may lead to unwanted complications.

Fasters lose weight quickly at first, but this loss is often from water and muscle mass rather than actual fat. This means the lost weight may return quickly after fasting ends, making the result temporary.

It may seem strange, but the body also relies on food as a water source up to 30%. Therefore, when a person completely abstains from eating, dehydration may occur even with large amounts of water intake. Common dehydration symptoms include fatigue, headache, dizziness, constipation, and low blood pressure.

Some people complain of dizziness or lightheadedness when standing, a condition known as orthostatic hypotension. Therefore, fasters are advised not to drive or engage in activities requiring high concentration during fasting.

Water fasting may worsen certain conditions such as gout, as it increases uric acid in the body. It is also risky for both types of diabetes patients, as it may cause severe blood sugar fluctuations. Additionally, it may negatively affect those with eating disorders such as bulimia.

While water fasting leads to rapid weight loss, it is not necessarily a healthy or permanent solution. Temporary results may mask nutrient loss and general energy weakness. For this reason, doctors recommend intermittent fasting instead of strict water fasting, as it allows balanced healthy meals at specific times without exposing the body to complete food deprivation.

It is essential to consult a doctor before starting any fasting regimen. Preparation is preferred by gradually reducing food intake two or three days before full fasting. Also, drink at least two to three liters of water daily and avoid strenuous activity during fasting. When breaking the fast, it is advisable to start with natural juices or small light meals, then gradually return to the regular diet.