Intermittent Fasting Side Effects

Intermittent fasting is a dietary plan that alternates between periods of fasting (not eating) and periods of eating. It does not prescribe what to eat but focuses on when to eat. The primary goal is to extend the time between your last meal of one day and your first meal of the next day. 

Intermittent fasting does not involve starving yourself. Rather, it focuses on significantly reducing calorie intake for short periods. Doing so makes your body accustomed to smaller portions and diminishes cravings for unhealthy snacks. 

There are several methods of intermittent fasting, but the most common ones include the following:

1. Time-Restricted Method: This type of fasting restricts the eating window. It includes the following ways: 
   16/8 method (16 hours of fast with an 8-hour eating window)
   14/10 method (fasting for 14 hours and eating during a 10-hour window)
   
2. Modified Fasting or the 5:2 Method: It involves eating normally for five days and significantly reducing calorie intake for two non-consecutive days a week. 
3. Alternate Day Fasting: In this method, fasting days are alternated with regular days where food and beverages can be consumed without restrictions.

In today’s world, intermittent fasting is considered one of the fastest ways to achieve 6-pack abs and a size zero body. It makes people curious whether fasting is safe. While generally considered safe for many people, it can have some potential side effects. Intermittent fasting side effects include:

Hunger and Craving for Food 

Intermittent fasting can sometimes lead to hunger as a side effect. Extended fasting periods with limited calorie intake may trigger a sudden increase in appetite. A study by T M Sundfør et al. was conducted in 2018 on 112 participants (50% men and 50% women) aged 21-70 years with a BMI of 30-45. According to it, intermittent fasting can cause elevated feelings of hunger.

Solution: Stay well-hydrated, consume filling, nutrient-dense foods in eating windows, and keep yourself busy to stay distracted from food. 

Low Energy and Fatigue 

Does intermittent fasting make you weak? The short answer is: Sometimes, but only during the initial days! Intermittent fasting can result in low blood sugar, making you feel weak and tired. 

Here’s the interesting thing: Boya Nugraha et al. conducted a study in 2020 with 34 healthy participants (male and female) older than 18 years. According to the study, intermittent fasting can reduce fatigue in healthy young males and females. It is especially true once your body adapts to the regular fasting regimen. 

Solution: Ensure hydration, get enough rest, and choose nutrient-dense foods to sustain energy during fasting periods. 

Headaches

Headaches are one of the most common intermittent fasting side effects when starting the fasting routine. A “fasting headache” is a type of headache that causes mild to moderate pain. It is usually experienced in the frontal region of the head. 

But did you know that individuals who frequently experience headaches are more prone to getting fasting headaches than those who rarely do? Plus, headaches usually occur after a minimum of 16 hours of fasting. 

Solution: Fasting headaches tend to subside within 72 hours following the resumption of food intake. To prevent headaches, maintain proper hydration, reduce caffeine consumption, and focus on good nutrition. 

Dehydration 

In the initial days of fasting, the body undergoes a natural process called diuresis or natriuresis of fasting. In this condition, the body expels significant amounts of water and salt through urine. Failing to replenish the fluids and electrolytes lost in this process can lead to dehydration. 

Moreover, individuals practising intermittent fasting might sometimes not consume enough fluids, particularly during the start of the fasting routine. You should also pay attention to the colour of your urine. Ideally, your urine should appear pale lemonade in colour. A darker hue may indicate dehydration.

Solution: Maintain a consistent daily water intake to ensure proper hydration.

Digestive Issues

Next on the list of intermittent fasting side effects are diarrhoea, constipation, and other digestive issues. Dietary alterations accompanying intermittent fasting programs might result in constipation, bloating and diarrhoea. Dehydration, another prevalent side effect of fasting, can worsen constipation.

Solution: Maintain proper hydration levels when engaging in intermittent fasting. Additionally, you must opt for nutrient-dense foods high in fibre to prevent constipation.

Mood Disturbances

It is common to experience irritability and mood swings during intermittent fasting, at least initially. Calorie restriction during periods of fasting can lead to low blood sugar. It can cause anxiety, irritation, and poor concentration. 

A study conducted by Ellen Watkins and Lucy Serpell in 2016 included 52 women with a mean age of 25. The study revealed that women experienced higher levels of irritability during fasting than when they were not fasting.

Solution: Practice stress-reduction techniques and consume nutrient-dense foods to support stable blood sugar levels.

Sleep Disturbances

In some cases, intermittent fasting can affect sleep patterns, causing difficulty falling or staying asleep. It is one of the most common consequences of fasting regimens. Françoise Wilhelmi de Toledo et al. conducted a study in 2019 with 1422 participants who fasted for 4-21 days. The study revealed that 15% of participants reported sleep disturbances during fasting. Moreover, these were more frequent than other side effects.

However, more research is required to establish the relationship between sleep disturbances and intermittent fasting. 

Solution: Maintain a consistent sleep schedule, manage stress, and avoid larger meals close to bedtime. 

Malnutrition

When done abruptly, intermittent fasting can lead to nutritional deficiencies. You must follow extended fasting periods with proper nutrition to ensure a healthy fasting routine. Often, during fasting, the primary focus is on calorie intake while overlooking the body’s nutritional needs. 

Solution: A nutritious diet plan is recommended for a successful and balanced fasting regimen. Seek guidance from a dietician to create a sustainable fasting-period diet plan. 

Hair Loss

One of the important intermittent fasting side effects is hair loss in individuals. It is well-known that a balanced diet plays a crucial role in maintaining healthy hair. Rapid calorie intake and nutritional pattern shifts can trigger a condition called telogen effluvium. It results in temporary hair loss due to the shock experienced by the hair follicles (a tube-like structure in the skin’s outer layer). 

Solution: If you find that you are losing more hair than usual when you wash, you should reconsider the composition of your meals and consult your physician to see if intermittent fasting is truly a good option for you.

Bad Breath 

During fasting, especially extended fasts, the body may enter a state of ketosis. It is a process where the body burns fat for energy instead of carbohydrates. This can lead to the production of acetone, a type of ketone. Acetone has a fruity scent, like nail polish remover, causing bad breath. 

When fasting for extended periods, your mouth can become dry due to less saliva production. Reduced saliva flow can lead to the growth of odour-causing bacteria, resulting in bad breath. Dehydration can also contribute to dry mouth and, subsequently, bad breath.

Solution: Stay well-hydrated, practice oral hygiene, and use mints or sugar-free gum to freshen your breath. 

Intermittent fasting is safe for most people, but it is not for everyone. Its appropriateness can vary depending on individual factors, health conditions, and goals. Some people may experience severe side effects if they participate in intermittent fasting. People who should avoid intermittent fasting include:

1. Women Who are Pregnant or Breastfeeding: Intermittent fasting can deprive these women and their children of essential nutrients for growth and development. 
2. Young Children and Teens Under Age 18: The growing bodies of these children require nutrition for proper development. Fasting can cause nutrient deficiencies.
3. Older Adults With Weakness Issues: Fasting can worsen age-related muscle weakness, impacting overall health. 
4. People With a History of Eating Disorders: Intermittent fasting can aggravate disordered eating behaviour.
5. Those With Type 1 Diabetes: Restrictive eating can affect blood sugar control and insulin management.
6. People With Dementia: This syndrome affects memory, thinking, and social abilities.
7. Individuals With Immunodeficiencies: It is a state in which the immune system cannot fight off infections or viruses effectively. Fasting can weaken the immune system, increasing the risk of infections. 
8. History of Traumatic Brain Injury or Post-Concussive Syndrome: It is a condition in which concussion symptoms (headaches, dizziness, concentration issues) persist longer than expected. Fasting might worsen neurological and cognitive symptoms. 

Individuals with kidney stones, gastroesophageal reflux, or other health conditions should talk to their doctor before starting intermittent fasting. 

If you encounter persistent side effects during intermittent fasting, this approach may not suit your body well. In such a situation, you should discontinue intermittent fasting and consult a doctor. Side effects that may require doctor consultation include:

1. Excessive hunger
2. Anxiety
3. Nausea
4. Headaches
5. Irritability or mood changes
6. Fatigue
7. Faintness

Intermittent fasting can offer various health benefits like weight management, improved metabolic health, etc. However, you must know the potential side effects, including hunger, fatigue, and digestive issues. While intermittent fasting side effects are typically manageable, it is crucial to develop a well-balanced plan. Consult a doctor to ensure a safe and effective fasting experience.

Experts at HexaHealth can provide valuable insights into your health and wellness through personalised recommendations. We can help you find the right doctors and hospitals for all your medical concerns. With HexaHealth, you can take proactive steps towards a healthier and more informed life.|

Suggested Reads