Can You Get Sick if You Don't Eat for a Week? The Serious Risks Explained

December 21, 2025 •

4 min read

According to health experts, the human body is quite resilient and can survive for weeks without food, provided it has enough water. However, this period of deprivation forces the body into a state of starvation, and the question of 'can you get sick if you don't eat for a week' is answered with a resounding yes, as the body begins to break itself down for energy, leading to numerous health complications.

Quick Summary

Prolonged food deprivation for a week or more can trigger a cascade of dangerous biological changes, including malnutrition, a weakened immune system, and severe metabolic shifts. These can lead to significant health issues, from digestive problems and nutrient deficiencies to serious organ dysfunction and immune system suppression.

Key Points

Immune System Suppression: A week without food significantly weakens the immune system, making a person highly vulnerable to infection and illness.
Metabolic Shift to Starvation: After initial glucose stores are depleted, the body enters ketosis and eventually starts breaking down muscle tissue for energy, leading to protein wasting.
Nutrient Depletion: Prolonged fasting causes severe malnutrition and a depletion of essential vitamins and minerals needed for vital bodily functions.
Organ Damage: Without fuel, the body's major organs, including the heart, kidneys, and liver, begin to lose function, which can be irreversible.
High Refeeding Risk: Reintroducing food after prolonged starvation can be dangerous and must be medically supervised to avoid potentially fatal refeeding syndrome.
Common Physical Symptoms: A week of not eating often results in extreme fatigue, weakness, dizziness, and nausea.
Cognitive and Emotional Impact: Starvation can cause emotional instability, cognitive impairment, and extreme food obsession.

The Body's Survival Mechanism: What Happens After a Week Without Food

When a person stops eating, the body activates a series of survival mechanisms to conserve energy and find fuel. This process moves through distinct phases, and by the end of one week, the body is well into a dangerous stage of self-cannibalization. Initially, within the first 24 to 72 hours, the body uses up its stored glucose (sugar) reserves from the liver. As this primary fuel source depletes, the liver begins breaking down stored fat into ketones for energy, a process known as ketosis. This is the phase many short-term dieters aim for. However, after about three days, the body moves into a more severe state. As the fat stores diminish, the body turns to a more perilous fuel source: protein.

The Breakdown of Protein and Muscle

At the one-week mark, most individuals' bodies will be actively breaking down muscle tissue to get the protein it needs to function. This is a severe form of starvation known as protein wasting, and it significantly impacts overall health. A healthy body is designed to conserve muscle, but prolonged fasting overrides this mechanism, leading to muscle loss, weakness, and potential damage to vital organs.

Weakened Immune System and Illness

One of the most significant consequences of not eating is a severely weakened immune system. A lack of proper nutrition deprives the body of essential vitamins, minerals, and other nutrients needed to produce and maintain a strong immune response. This makes a person far more susceptible to infections and illnesses. Studies have shown a strong link between malnutrition and a compromised immune system, leading to more frequent and prolonged bouts of sickness.

Here are some of the ways a weakened immune system manifests:

Inability to fight off common infections effectively.
Slower wound healing.
Increased risk of developing more severe health complications from minor illnesses.

The Physiological Consequences of Starvation

Beyond muscle loss and a suppressed immune system, starvation sets off a chain reaction of physiological issues that can leave lasting damage.

Common effects of not eating for a week:

Fatigue and Weakness: With no fuel from food, energy levels plummet. This can lead to extreme tiredness, sluggishness, and overall physical weakness.
Nausea and Dizziness: Low blood sugar and the buildup of stomach acid can cause feelings of nausea, which may lead to vomiting. Dizziness and lightheadedness are also common symptoms.
Digestive Problems: The lack of food can lead to gastrointestinal dysfunction, including constipation or, in some cases, diarrhea.
Hypoglycemia: Dangerously low blood sugar levels can cause a range of symptoms, including shakiness, irritability, and, in severe cases, confusion, slurred speech, or seizures.
Electrolyte Imbalances: The body's metabolic shifts can cause dangerous imbalances in electrolytes, which are crucial for heart function and other vital processes.

Comparison Table: Short-Term vs. Prolonged Fasting Risks


Feature	Short-Term Fasting (1-3 Days, medically supervised)	Prolonged Fasting (1+ Week without food)
Primary Energy Source	Stored glucose and early ketosis from fat stores.	Later-stage ketosis and eventual protein/muscle breakdown.
Physical Symptoms	Hunger pangs, headaches, irritability, and fatigue.	Severe fatigue, weakness, dizziness, and organ deterioration.
Nutritional Status	Minimal risk of severe deficiency if well-nourished prior.	High risk of severe malnutrition, vitamin, and mineral deficiencies.
Immune System Impact	Generally minor or temporary effects.	Significant weakening of the immune system.
Organ Function	Typically normal; may experience stress on the liver.	Progressive decline in heart, kidney, and liver function.
Muscle Mass	Minimal, if any, loss of muscle.	Significant muscle wasting and protein breakdown.
Refeeding Risk	Low risk of refeeding syndrome.	High risk of refeeding syndrome, a dangerous electrolyte disorder.

The Danger of Refeeding Syndrome

After a prolonged period without food, the body's metabolism is completely altered. Reintroducing food too quickly can be deadly due to a condition called refeeding syndrome. This occurs when the sudden influx of nutrients overwhelms the body's starved systems, causing rapid shifts in fluids and electrolytes. This can lead to heart failure, respiratory failure, and other life-threatening complications. A person who has been without food for a week or more requires careful medical supervision during refeeding to safely restore their nutrition.

Conclusion

While the human body is capable of surviving for several weeks without food, the process is far from harmless. By the one-week mark, a person will be experiencing severe symptoms as the body consumes its own muscle tissue, and the immune system becomes critically compromised. The risk of illness from a weakened immune system, combined with the stress on major organs, makes not eating for a week a dangerous and medically inadvisable practice. If you or someone you know is experiencing involuntary starvation, it is crucial to seek immediate medical attention. For guidance on safe fasting, it's best to consult a healthcare professional. For information on seeking professional help, reputable organizations like Equip Health offer resources regarding disordered eating(https://equip.health/articles/food-and-fitness/what-happens-if-you-dont-eat-enough).

Disclaimer: The information in this article is for educational purposes only and is not a substitute for professional medical advice.

Frequently Asked Questions

Yes, a week without food can significantly weaken your immune system because your body is deprived of the essential nutrients needed to produce and maintain immune cells.

No, it is not safe or advisable to fast for a week for weight loss without medical supervision. Prolonged fasting poses serious health risks, including severe malnutrition, muscle loss, and organ damage.

The first thing that happens is your body uses up its stored glucose (sugar) for energy. This typically occurs within the first 24 to 72 hours.

Refeeding syndrome is a potentially fatal condition that can occur when a severely malnourished person reintroduces food too quickly. It causes dangerous shifts in fluid and electrolyte levels, which can lead to heart failure and other complications.

While it varies depending on individual factors, medical consensus suggests a well-hydrated person can survive for approximately one to two months without food, though serious health issues arise much sooner.

Yes, not eating can cause nausea. This is often due to low blood sugar and the buildup of stomach acid in an empty stomach.

Initial serious signs can include extreme fatigue, dizziness, severe weakness, and changes in mood. These indicate that your body is not getting the fuel it needs.