Fasting has become increasingly popular as people experiment with intermittent fasting, time-restricted eating and other dietary routines. But going without food for several consecutive days is very different from the shorter fasting windows commonly discussed online.
Fitness trainer Sara Kachhara recently revealed that she voluntarily went 13 days without eating, documenting some of the unusual sensations she experienced during the prolonged fast.
“I voluntarily went 13 days without eating anything. The craziest part? I started with three days….and it kept on…around day 10-11, I could clearly feel the changes in my body to a point that I was creeped out by it. When I drank water, I could feel it churning in my stomach. I could hear my heartbeats. The interesting thing was not about the body but the mind,” she wrote in an Instagram post.
Her experience raises an important question: Is a 13-day fast advisable, and what happens to the body when food is withheld for that long?
What Happens to the Body During a Prolonged Fast?
Clinical nutritionist Gulnaaz Shaikh of Healthyz explained that the body changes how it produces and uses energy when food intake is significantly reduced.
Initially, the body primarily uses stored glycogen, the form in which carbohydrates are stored. As glycogen reserves decline, the body increasingly turns to stored fat for energy and produces more ketones.
However, prolonged fasting does not mean the body burns only fat.
“With prolonged food deprivation, protein and muscle tissue can also be broken down,” Shaikh said.
This is one reason why a drop on the weighing scale during an extended fast should not automatically be interpreted as a loss of body fat. Changes in body weight can also reflect water loss and reductions in lean tissue.
Extended food deprivation may also affect energy levels, concentration, blood pressure and the intake of essential nutrients.
Why Can Someone Feel Better While Fasting?
Some people may report feeling lighter or experiencing greater mental clarity during a fast. Shaikh said these sensations can be genuine, but they do not necessarily demonstrate that prolonged fasting is safe or beneficial.
“Eating less may reduce bloating or digestive discomfort, while changes in fluid balance can make someone feel lighter,” she explained.
The psychological experience can also play a role. Some people may associate fasting with discipline or mental clarity.
However, feeling well during a fast is not enough to establish that the practice is appropriate for everyone.
A 13-Day Fast Is Not the Same as Intermittent Fasting
Shaikh stressed that the term “fasting” can describe very different practices.
Someone following a time-restricted eating pattern is in a substantially different physiological situation from a person consuming no food for many days.
“A person consuming water, electrolytes or some calories is in a very different situation from someone having no food at all,” she said.
Therefore, experiences associated with intermittent fasting should not automatically be applied to an extended period of complete food deprivation.
Who Should Avoid Prolonged Fasting Without Medical Supervision?
According to Shaikh, certain people face additional risks from experimenting with prolonged fasting independently.
These include people with:
- Diabetes
- Kidney or liver disease
- A history of eating disorders
- Low blood pressure
- Nutritional deficiencies
- Other chronic health conditions
Pregnant and breastfeeding women, children and older adults also have specific nutritional requirements and should not undertake prolonged fasting without appropriate medical guidance.
Anyone with an underlying medical condition should discuss fasting with a qualified healthcare professional before making significant changes to their food intake.
What Is a Safer Approach to Fasting?
For most people, the quality and consistency of their overall diet are more important than trying to see how long they can go without eating.
Shaikh recommended focusing on a sustainable eating pattern that provides adequate protein, vegetables, whole grains, healthy fats and sufficient fluids.
People interested in time-restricted eating or intermittent fasting may consider a moderate approach tailored to their health, daily routine and nutritional requirements rather than attempting an extreme fasting challenge seen on social media.
Sara Kachhara’s 13-day experience may have been personally meaningful to her, but an individual account should not be treated as evidence that prolonged fasting is safe or suitable for everyone.
Is Fasting for 13 Days Advisable?
A 13-day fast without food is an extreme form of food restriction, not a routine fasting pattern. It can involve significant changes in hydration, blood pressure, nutrient availability, energy metabolism and lean tissue. Anyone considering prolonged fasting should speak with a healthcare professional beforehand rather than attempting it based on a social-media account.
