Let's Duke It Out

Can Intermittent Fasting Cause Side Effects

Can Intermittent Fasting Have Negative Side Effects?

Intermittent fasting is a diet concept that has gained popularity in recent years. It consists of fasting intervals followed by eating phases. While there are some possible advantages to this method, there are also some disadvantages to consider.

One of the primary issues with intermittent fasting is that it is difficult to maintain. Going 16 hours without food might be difficult if you’re accustomed to eating three meals a day. When you eventually sit down to eat, you run the danger of overeating. After all, it’s difficult to resist temptation when you’re hungry. Another issue to consider is that intermittent fasting might cause food cravings. When your body goes without meals for an extended length of time, it may begin to want high-calorie, high-fat items. This may also lead to overeating and derail your weight-loss efforts.



People who fast often complain about feeling “hangry.” In other words, people are irritated because they are hungry. But why is this happening? There are many hypotheses. One theory is that when we fast, our blood sugar levels decrease. This might produce irritation and poor energy, which can lead to desires for sweet or high-carbohydrate meals. Another notion is that when we are hungry, our bodies create more ghrelin, a hormone. Ghrelin signals the brain from the stomach that we need to eat. Ghrelin levels have been related to emotions of irritation and agitation (1). Whatever the reason, feeling “hangry” is unquestionably a disadvantage of intermittent fasting.

If you are experiencing this side effect, there are a few things you may do to assist alleviate it. Make sure you’re getting enough water and keeping hydrated. This signals to the brain that the stomach is full, which lowers appetite and hunger (2). When you do have a meal, make it high in protein, healthy fats, and fiber. These meals digest more slowly than other foods, which helps keep hunger at away. And, if everything else fails, remember that this is merely a passing phase; once you break your fast, your hunger and fury will go!


Low blood sugar

Low blood sugar is another possible negative effect of intermittent fasting. Fasting forces your body to break down stored glycogen for energy. Glycogen is a chemical substance made up of glucose molecules linked together with water. It is kept in the liver and the muscles. Your glycogen reserves may be depleted during a fast, resulting in low blood sugar levels (3). This might result in dizziness, lightheadedness, headaches, and weariness (4). If you experience any of these symptoms while fasting, it is critical to consume meals rich in lean meat, fish, and vegetables to keep your blood sugar levels stable. Alternatively, attempt fasting for a shorter period of time while your body adjusts to the new routine.

Another alternative is to observe if these symptoms occur at certain times of day. If you wake up feeling dizzy or with a headache, skipping breakfast may not be the greatest choice. However, if you are irritable and exhausted in the evening, eating a good dinner may assist. That being stated, do not eat within two hours of going to bed. Going to bed on an empty stomach may create indigestion and heartburn, resulting in interrupted sleep (5), which may explain why you wake up feeling lethargic. You can reduce your risk of low blood sugar and get the advantages of intermittent fasting with a little forethought and preparation.

Tiredness and fatigue

Another negative effect of intermittent fasting is extreme fatigue. This is associated with low blood sugar and eating the ‘wrong’ things while eating. Processed meals that digest fast are the incorrect foods. These cause a brief, dramatic increase in blood sugar and hence energy. Make sure you consume enough of B-vitamin-rich foods to help you feel less weary. These vitamins are essential for releasing energy from meals. Eggs, dairy, fortified cereals, and nutritional yeast are excellent sources, as are green vegetables like cabbage and spinach, organ meats, shellfish, and legumes (6).


Constipation may also be caused by intermittent fasting (7). Fasting may cause the digestive process to slow down, resulting in firm, difficult-to-pass feces. When you consume three meals a day, each one efficiently drives the next through your digestive tract. Consider it like a conveyor belt. When you only eat one or two meals a day, the passage of food through the stomach slows down. Furthermore, when you do eat, you are more likely to overeat, which may lead to constipation.

To prevent this issue, drink enough of water to soften the stools and flush food through the digestive tract. Eating high-fiber meals, such as leafy green vegetables, also aids in the movement of food through the digestive tract (8). If you don’t like green veggies, consuming items rich in water like melon, cucumber, celery, and tomatoes will suffice.


Some individuals may encounter digestive problems such as constipation, while others may feel nausea. When you are hungry and have not eaten in a while, stomach acid might build up since there is no food to break down. This might make you feel nauseated. Another reason for nausea during intermittent fasting is dehydration (9). Drinking enough of water is essential, particularly during fasting. Every aspect of our body need water to operate correctly (10). If you’re feeling sick and also light-headed, weary, or dizzy, a glass of water may be all you need to feel better.

It interferes with sleep

Another disadvantage of intermittent fasting is that it might interfere with the body’s natural circadian cycle. The circadian rhythm is a 24-hour internal clock that governs several vital activities such as sleep, hormone production, and metabolism (11). When the body’s circadian cycle is out of sync, intermittent fasting may actually assist to reset it (12). When taken excessively or wrongly, however, it may have the opposite effect, disrupting the body’s normal sleep-wake cycle.

This is particularly true when meals are consumed after dark. Melatonin, the sleep hormone, is created as darkness falls. This alerts the liver (13), as well as the digestive system, that it is time to slow down (14). As a result, if you consume a large meal in the evening, particularly in the winter when it becomes darker early, it will not be digested properly. This might cause indigestion, which can disrupt your sleep (15).

While there are certain disadvantages to intermittent fasting, they are readily addressed. The body need time to adjust to any change in the way you eat or what you consume. However, once it has adapted, you may reap the numerous benefits of intermittent fasting. If you run into difficulties with this method of eating, there is plenty of support available online, or you may seek guidance from a medical practitioner.

Finally, keep in mind that intermittent fasting is not a miracle cure. It necessitates making good dietary choices and remembering why you began in the first place.


  1. Mood disorders: A potential link between ghrelin and leptin on human body?
  2. Effect of excessive water intake on body weight, body mass index, body fat, and appetite of overweight female participants
  3. Hypoglycemia
  4. Low blood sugar (hypoglycaemia)
  5. Is Late-Night Snacking Really So Wrong?
  6. B vitamins and folic acid
  7. Health Effects of Alternate-Day Fasting in Adults: A Systematic Review and Meta-Analysis
  8. Concerned About Constipation?
  9. Does Hunger Cause Nausea?


The post Can Intermittent Fasting Cause Side Effects appeared first on

The post Can Intermittent Fasting Cause Side Effects appeared first on

You Might Also Like