Intermittent fasting has become very popular for weight loss and improving health in recent years. But the question is does it really work, or is it just another trend?

Many people have seen benefits like weight loss, better energy levels, improved digestion, and even a lower risk of certain diseases. But it is not for everyone, and if done wrong, it can have some downsides too.

In this guide, we will explain what intermittent fasting is, how it works, the different ways you can try it, and the possible benefits and risks. Whether you want to lose weight, boost your energy, or just feel healthier, understanding intermittent fasting will help you decide if it is the right fit for you.

What is Intermittent Fasting?

Intermittent fasting means eating your food during fixed hours and not eating for the rest of the time. Intermittent fasting is more about when you eat rather than what you eat. However, eating nutritious foods during your eating window is important for maintaining good health and getting the best benefits. It is not about what you eat but It is about when you eat. Instead of eating throughout the day, you have specific hours or days when you eat and times when you don’t.

Intermittent fasting has been linked to weight loss, better digestion, improved energy levels and even a lower risk of certain diseases. It is a simple but powerful way to help your body work more efficiently and feel better overall.

Common Types of Intermittent Fasting

Time Restricted Eating (16:8 Method)

In this method, you fast for 16 hours and eat during an 8 hour window each day. It is the most popular because it is easy to fit into a normal routine. For example, you might skip breakfast, eat between 12 PM and 8 PM and fast the rest of the time.

5:2 Diet

With this method, you eat normally for five days a week and limit your calorie intake to about 500–600 calories on two non consecutive days. It is a simple way to reduce overall calorie intake without feeling deprived every day.

Alternate Day Fasting

In this approach, you alternate between fasting and eating days. On fasting days, you might eat very little or nothing at all. This can help reduce overall calorie intake and improve metabolism.

24 Hour Fasting

Also known as the "Eat-Stop-Eat" method, this involves fasting for a full 24 hours once or twice a week. For example, you might stop eating after dinner and not eat again until dinner the next day.

The Science Behind Intermittent Fasting

Intermittent fasting works by changing how your body gets its energy. Normally, your body uses glucose (sugar) from the food you eat for energy. But after about 12 hours of not eating, your body doesn't run out of glucose but it switches from using glucose  and starts using fat as fuel instead of glucose. Your body typically begins shifting from glucose to fat for fuel approximately 12–16 hours after your last meal.  Glycogen stores significantly decrease, prompting your body to switch primarily to fat breakdown for fuel. This is when increased fat burning begins.

Autophagy is like cellular recycling. It involves the cell breaking down and clearing out damaged proteins, organelles, and other cellular debris to reuse or recycle the components. This process doesn't typically kill the entire cell; instead, it rejuvenates and improves cellular health. we don't have to put this technical explanation but it's cell renewal, not new cells.

Real Benefits of Intermittent Fasting

While intermittent fasting is often promoted for weight loss, it offers several science-backed health benefits beyond just dropping a few pounds:

1. Weight Loss and Fat Burning

Intermittent fasting reduces overall calorie intake and increases the body’s ability to burn stored fat. Studies show that it can lead to a 3–8% reduction in body weight over 3–24 weeks.

2. Improved Insulin Sensitivity and Blood Sugar Control

Fasting reduces insulin resistance, which lowers blood sugar levels and decreases the risk of type 2 diabetes. Studies show that fasting can lower fasting blood sugar levels by up to 6%.

3. Heart Health

Intermittent fasting helps reduce LDL (bad) cholesterol, triglycerides, and inflammatory markers, all of which are linked to heart disease.

4. Enhanced Brain Function

Fasting increases levels of brain-derived neurotrophic factor (BDNF), which improves cognitive function and reduces the risk of neurodegenerative diseases like Alzheimer’s and Parkinson’s.

5. Longevity and Anti Aging

Animal studies suggest that intermittent fasting may increase lifespan by improving metabolic health and reducing oxidative stress and inflammation.

Risks and Potential Downsides of Intermittent Fasting

Intermittent fasting has so many benefits but it is not for everyone. Here are some potential risks:

1. Increased Hunger and Cravings

Fasting can increase ghrelin (the hunger hormone) levels, leading to intense hunger and cravings, which may cause overeating during eating windows.

2. Fatigue and Low Energy

Fasting can lead to low blood sugar levels, resulting in fatigue, headaches and dizziness. This is more common when starting out.

3. Irritability and Mood Swings

Low blood sugar levels during fasting periods can cause irritability, mood swings and difficulty concentrating.

4. Overeating During Eating Windows

Some people may compensate for fasting by binge-eating during their eating window, which can negate the benefits of fasting.

How to Start Intermittent Fasting

Choose a Method: Start with the 16:8 method it is the easiest and most sustainable for beginners.

Stay Hydrated: Drink plenty of water, herbal teas and black coffee during fasting periods.

Eat Nutrient-Dense Foods: Focus on whole grains, lean proteins, healthy fats and plenty of fruits and vegetables during your eating window.

Listen to Your Body: Adjust your fasting periods based on how you feel and how your body responds.

Common Misconceptions About Intermittent Fasting

Despite its growing popularity, there are many myths about intermittent fasting that can confuse people. Let’s clear up the most common ones:

1. Myth: Intermittent fasting slows down your metabolism
Actually, short-term fasting (up to 48 hours) can boost your metabolism by increasing levels of norepinephrine (also known as noradrenaline in Europe), which helps burn fat. However, fasting for more than 72 hours may slow down your metabolism.

2. Myth: You will lose muscle mass
Research shows that intermittent fasting preserves muscle mass better than regular calorie-restricted diets, especially when combined with strength training. Your body shifts to burning fat for energy instead of muscle tissue.

3. Myth: You can not get enough nutrients in a short eating window
If you eat nutrient rich foods like lean proteins, whole grains, fruits, and vegetables during your eating window, you can easily meet your daily nutrient needs.

4. Myth: Fasting causes nutrient deficiencies
Intermittent fasting will not cause nutrient deficiencies unless your overall diet is poor. Eating balanced meals during your eating window ensures you get enough vitamins and minerals.

5. Myth: Fasting means you can not work out
You can still exercise while fasting. In fact, moderate workouts during fasting can improve fat burning and muscle tone. Some studies even suggest that working out in a fasted state increases growth hormone levels, which supports muscle retention and fat loss.

Who Should Try Intermittent Fasting

Intermittent fasting can be a great choice for certain people based on their health, lifestyle and goals. If you fall into any of these categories intermittent fasting might be a good option for you:

1. People looking to lose weight and burn fat

• Fasting naturally reduces overall calorie intake by limiting your eating window which helps with weight loss.

• It boosts metabolism by increasing noradrenaline and human growth hormone levels which enhance fat burning.

• During fasting periods, the body shifts from burning glucose to burning stored fat for energy promoting fat loss.

2. People with insulin resistance or type 2 diabetes (under medical supervision)

• Fasting lowers insulin levels and can improve insulin sensitivity, which may help reduce the risk of type 2 diabetes. However, its benefits are most effective when blood sugar levels are already stable with minimal fluctuations.

• Studies show it can lower fasting blood sugar and improve long-term blood sugar control (HbA1c levels).

• If you’re on diabetes medication, consult with a doctor first as fasting may lower blood sugar levels too much.

3. Those Looking to Improve Heart Health

• Fasting helps reduce cholesterol levels, triglycerides and blood pressure, which lowers the risk of heart disease.

• Intermittent fasting can help reduce inflammation and oxidative stress, which are linked to heart problems. However, these benefits are more effective when blood sugar levels are already stable. 

• Research shows fasting can increase HDL (good) cholesterol and reduce LDL (bad) cholesterol.

4. Athletes and fitness enthusiasts (with proper planning)

• Fasting can help athletes burn fat while preserving muscle mass.

• Fasted workouts increase the production of growth hormone which supports muscle repair and growth.

• The 16:8 method (16 hours of fasting, 8-hour eating window) allows athletes to fuel up around workouts while still benefiting from fasting.

5. People with digestive issues or inflammation

• Fasting gives your digestive system a break which can reduce bloating and improve gut health.

• Lowering inflammation through fasting may help with autoimmune issues and digestive problems like IBS.

• Fasting reduces the production of inflammatory markers improving overall gut health.

6. People seeking better mental clarity and brain health

• Fasting increases the production of brain-derived neurotrophic factor (BDNF), which supports brain health and improves memory and focus.

• It triggers autophagy, a process where the body renews itself by clearing out damaged cells. This may help protect against Alzheimer’s and Parkinson’s.

• Many people report improved focus and mental clarity while fasting.

7. People interested in longevity and anti aging

• Fasting activates genes linked to longevity and reduces oxidative stress which may promote a longer lifespan.

• Animal studies show that intermittent fasting extends lifespan by improving cellular health.

• Fasting enhances autophagy, helping the body remove damaged cells and improve overall health at the cellular level.

Who Should Avoid Intermittent Fasting

Intermittent fasting is not for everyone. For some people, it can do more harm than good especially if they have certain health issues or lifestyle factors. Here is who should avoid or be cautious with fasting:

1. Pregnant or breastfeeding women

• Pregnant and breastfeeding women need consistent nutrients and calories to support the baby’s growth and milk production.

• Fasting can lead to nutrient deficiencies and may reduce milk supply.

• Hormonal changes during pregnancy and breastfeeding can increase hunger and fatigue, making fasting difficult and unsafe.

2. People with a history of eating disorders

• Fasting can trigger unhealthy eating patterns and worsen existing eating disorders.

• Restrictive eating windows may lead to binge eating during feeding periods.

• People with anorexia, bulimia, or binge eating disorder should avoid fasting unless under medical supervision.

3. People with low blood sugar (Hypoglycemia)

• Fasting can cause blood sugar levels to drop too low, leading to dizziness, fatigue, headaches and fainting.

• Skipping meals can make low blood sugar symptoms worse and cause mood swings.

• Those prone to low blood sugar should stick to a regular eating schedule to avoid energy crashes.

4. Underweight individuals or those with malnutrition

• People who are underweight need more calories and nutrients to maintain a healthy weight.

• Fasting can reduce nutrient intake even further leading to more health problems.

• Anyone with a BMI under 18.5 should avoid fasting or consult a doctor first.

5. Children and Adolescents

• Growing children and teenagers need a steady intake of calories and nutrients to support growth and development.

• Fasting can interfere with their growth patterns and energy levels.

• Restrictive eating at a young age can lead to unhealthy eating habits later in life.

6. People with High Stress or Poor Sleep

• Fasting increases cortisol (stress hormone) levels which can make stress and anxiety worse.

• Poor sleep combined with fasting can lead to fatigue, irritability and trouble focusing.

• It’s important to improve sleep and reduce stress before trying fasting.

7. People Taking Certain Medications

• Some medications (like those for blood pressure, diabetes and thyroid issues) need to be taken with food.

• Fasting without adjusting medication timing can cause health issues.

• Consult a doctor before fasting if you take regular medication.

8. People with digestive issues (Like GERD or ulcers)

• Fasting can increase stomach acid production, worsening acid reflux (GERD) and stomach ulcers.

• Long periods without food may trigger heartburn and digestive discomfort.

• Eating balanced meals at regular intervals is usually better for people with digestive problems.

9. A women in perimenopause should avoid intermittent fasting because: Why Women in Perimenopause Should Be Cautious with Intermittent Fasting

Intermittent fasting (IF) can be a powerful tool for metabolic health, but for women in perimenopause, it requires a more strategic approach. Here’s why:

• (i) Hormonal Changes = Higher Stress Sensitivity

  During perimenopause, estrogen and progesterone start fluctuating wildly. These hormones impact:

  Cortisol (stress hormone) → Women in perimenopause often have higher cortisol levels, and fasting can further increase stress on the body, leading to fat storage (especially around the belly).

  Insulin sensitivity → Estrogen helps regulate insulin. As estrogen drops, women become more insulin-resistant, making it harder to manage blood sugar during fasting.

  Solution:

  • Avoid fasting longer than 12–14 hours if you feel stressed or have poor sleep.
  • Focus on blood sugar stability first before jumping into long fasts.
  
  

  (ii) Blood Sugar Swings Can Trigger Weight Gain

  Perimenopause = more frequent blood sugar crashes due to increased insulin resistance.

  If blood sugar drops too low during fasting, your body responds by spiking cortisol → leading to increased hunger, cravings, and potential weight gain.

  Solution:

  • Protein-first approach: Break your fast with 30g+ protein to stabilize blood sugar.
  • Try circadian fasting: A 12-hour fast (7 PM – 7 AM) works better than extreme fasting windows.
  
  

  (iii) Brain Fog & Mood Swings Can Get Worse

  Estrogen supports serotonin (mood stabilizer) and dopamine (motivation & focus).

  Long fasting periods can deplete neurotransmitters, worsening brain fog, anxiety, and mood swings.

  Women in perimenopause often struggle with poor sleep → fasting can further disrupt melatonin & cortisol rhythms, making sleep worse.

  Solution:

  • Don’t fast on high-stress days or after bad sleep.
  • Include healthy carbs in the evening to support serotonin & sleep.
  
  

  (iv) Muscle Loss Risk Increases

  Estrogen protects muscle mass, but during perimenopause, estrogen levels decline. 

  This makes it harder to maintain muscle, and prolonged fasting can worsen muscle loss if protein intake is insufficient.

  Solution:

  • Prioritize protein intake after breaking a fast (aim for at least 30g of high-quality protein).
    
  • Incorporate strength training to preserve muscle mass.
    
  • Avoid extreme fasting durations (keep it within 12–14 hours).