What Happens to the Body if You Starve Yourself for a Week?

Food and water are essential to life. For your body to survive, it needs energy from different food sources. Hydration from clean water is also crucial for proper body functioning.

But it is also important to note that our body can survive for days without water. The human body can also live without food for days and, in some cases, weeks, due to adjustments to our energy consumption and metabolism.

Why the variation in the period?

Eliminating water and food intake for a significant period is starvation. After one or two days without water or food, your body switches into starvation mode. At that time, the body’s function changes to reduce the amount of energy it expends. Prolonged starvation eventually leads to death.

Here’s the thing: there is no “rule of thumb” for how long the body can survive without food. There is a lack of data on starvation studies because studying starvation in human subjects is highly unethical.

A few studies explore old research on starvation while also examining more recent incidences of starvation in the real world. These instances include religious fasts, hunger strikes, and other similar cases.

These studies have uncovered some observations about starvation:

1. A study published in Archiv Fur Kriminologie (1) suggests that the human body can survive up to 21 days without food and water. Furthermore, it indicates that the survival period can last up to two months if the affected person has access to adequate water intake.

2. Modern-day hunger strikes have provided more insight. A study published in the British Medical Journal (2) reported some hunger strikes after 21–40 days. The strikes ended after the participants began to experience severe, life-threatening symptoms.

3. There appears to be a specific “minimum” number for survival on the body mass index scale. For example, a study published in the journal Nutrition (3) suggests that men with a BMI lower than 13 and women with a BMI lower than 11 do not possess the capability to sustain life.

4. A study published in the British Medical Journal (4) reports that people who have an average weight will lose more muscle tissue and body weight faster than those who are obese during the first three days of starving.

5. An article in the journal Nutrition suggests that women’s body composition allows them to withstand starvation for a longer time than men (5).

How is this possible?

Many people think it is impossible to live for days and weeks without food and water. After all, we get irritable and tired after a daylong fast.

The thing is, the human body adjusts itself if you do a short-term fast or do not have access to water and food for extended periods. This explains why people can engage in religious fasts without causing extensive damage to their bodies.

It takes at least eight hours of no eating for a change to occur in your body’s mode of operation. Before that, it usually functions as if you were eating normally.

Usually, your body breaks down the food you eat into glucose. Your body burns this glucose for energy. Your body will begin to convert glycogen from your muscles and liver into glucose if you’ve not had food for 8–12 hours. Staying without food for this long causes depletion of your glucose storage.

When your glycogen and glucose stores are depleted, your body switches to amino acids as its energy source. This affects your muscles and may sustain your body for three days of starvation (6) before metabolism causes a significant shift to preserve lean body tissue.

To prevent loss of excess muscle tissue, your body switches to fat stores to produce ketones for energy. This process is known as ketosis. You will experience immense weight loss at this time. A person who has more fat stores can typically survive longer during starvation. After a complete metabolism of all fat stores, the body reverts to muscle breakdown for energy because it is now the only energy source.