Fasting is a common practice in Nigeria — often for religious, cultural or health reasons. While many people focus on the spiritual benefits, it is also important to understand what actually happens inside your body when you stop eating.
Quick Answer On What Happens When You Fast
When you stop eating, your body first uses stored sugar (glycogen) for energy. After this is depleted, it switches to burning stored fat. During fasting, hormone levels change, digestion slows, and brain function may feel sharper or more strained depending on hydration and duration. Short-term fasting can be safe for many people, but prolonged or repeated fasting without proper care may affect hormones, fertility, and overall health.
Knowing this helps you fast wisely, avoid harm, and recognise when adjustments are needed.
What Is Fasting?
Fasting is the voluntary abstinence from food — and sometimes drink — for a specific period. It can last from a few hours to several days, depending on personal, religious or health goals.
When you stop eating, your body does not shut down. Instead, it switches fuel sources and activates survival systems designed to keep you alive.
What Happens In The First 6–24 Hours Of Fasting
1. Your Body Uses Stored Sugar (Glycogen)
After your last meal, your body uses glucose from the food you ate. Once that runs out, it turns to glycogen, a stored form of sugar found in the liver and muscles.
This usually lasts 12–24 hours.
Common signs at this stage
- Hunger
- Headaches
- Mild weakness
- Irritability
These symptoms are normal and usually temporary.
What Happens After 24–48 Hours
2. Your Body Switches To Fat Burning
Once glycogen is depleted, your body begins to burn stored fat for energy. This process produces substances called ketones.
This is why some people lose weight during fasting.
You may notice
- Reduced appetite
- Mental clarity (for some people)
- Fatigue or dizziness if hydration is poor
What Happens To Your Hormones During Fasting?
Fasting affects hormones that regulate hunger, stress, and reproduction.
Insulin levels drop, allowing fat burning
Cortisol (stress hormone) may rise, especially with long fasts
Reproductive hormones can be affected, particularly in women
This is why extended fasting may cause:
- Missed or delayed periods
- Reduced ovulation
- Changes in sperm quality in men
What Happens To Your Digestive System When You Fast?
Your digestive system gets a temporary rest during fasting. This can help reduce bloating and improve gut sensitivity.
However, breaking a fast abruptly with heavy meals can cause:
- Stomach pain
- Diarrhoea
- Acid reflux
Gentle meals are important when breaking a fast.
What Happens To Your Brain and Mood When You Fast?
Fasting can increase focus and alertness in the short term. However, prolonged fasting without proper hydration can lead to:
- Mood swings
- Irritability
- Poor concentration
- Anxiety
These effects are stronger in people who already struggle with stress or poor sleep.
Is Fasting Safe For Everyone?
Fasting is not the same for everyone.
People who should seek medical advice before fasting include:
- Pregnant or breastfeeding women
- People with diabetes
- Those with eating disorders
- Individuals with anaemia
Women with irregular menstrual cycles or fertility challenges
Adjusting a fast is not a sign of weakness or lack of faith — it is wisdom.
In Nigeria, fasting is widely practised during religious programmes in churches and mosques, often without medical guidance. This makes understanding how the body responds to fasting especially important.
Many Nigerians engage in prolonged fasting while managing busy work schedules, heat exposure and limited hydration, which can intensify the physical effects of fasting.
Can Fasting Be Healthy?
Yes, when done correctly.
Healthy fasting includes:
- Adequate hydration
- Listening to your body
- Proper nutrition before and after fasting
Avoiding extreme or prolonged fasts without guidance
Key Takeaway
Fasting is not just a spiritual activity — it is also a biological process. When you understand what happens to your body when you stop eating, you can fast in a way that honours both your faith and your health.
Your body is not your enemy. Caring for it allows you to serve God and others better.
Frequently Asked Questions (FAQs)
Question: Does fasting detox the body?
Answer: The body already detoxifies itself through the liver and kidneys. Fasting can support these organs by reducing digestive load, but it does not replace the body’s natural detox systems.
Question: Can fasting cause missed periods?
Answer: Yes. Extended or frequent fasting can disrupt hormonal balance, especially in women, leading to delayed or missed menstrual periods.
Question: Is weakness during fasting normal?
Answer: Mild weakness or hunger is common, especially in the first few days. Severe weakness, dizziness or fainting is not normal and may mean the fast needs to be modified or stopped.
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Question: Is it okay to break a fast for health reasons?
Answer: Yes. Protecting your health is not a lack of faith. Adjusting or stopping a fast due to health concerns is a wise and responsible decision.