9 Dangerous Side Effects of Intermittent Fasting

9 dangerous side effects of intermittent fasting. Photo: pexels
9 dangerous side effects of intermittent fasting. Photo: pexels

You may have already heard about intermittent fasting. But if you are not familiar with the term, it refers to the practice of limiting what you eat in a day to a specific time window. Although there is a lot of talk about its benefits, the side effects of intermittent fasting can be dangerous.

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The benefits of intermittent fasting include weight loss and improved concentration. However, to enjoy this, you must do it correctly.

“It’s important to find out which intermittent fasting style works for you, whether it’s a shorter or longer fasting window or just doing it a few days a week,” notes nutritionist Alyssa Koens. “If you’re consuming too few calories or nutrients during fasting, you may experience side effects.”

In this regard, you should not start an intermittent fasting plan without first talking to an endocrinologist or nutritionist and assessing your risks. Read on to understand why the practice can be dangerous for some people.

Short-Term Dangerous Side Effects of Intermittent Fasting

1 — Anger or bad mood associated with hunger from intermittent fasting

A feeling of irritability and bad mood can take over you when you feel hungry. According to the magazine, if you consume enough protein at the end of the day or night, you should not wake up “starving” in the morning. But if you are, “it’s a sign that you need to make some adjustments to your diet during the calorie intake period to avoid bad mood.”

It is also worth noting that for some people (like those who train a lot), not eating for extended periods may not be suitable.

2 — Fatigue and mental confusion

Feeling excessively tired during the day or making mistakes in basic activities may be signs that you are not consuming the right foods before fasting or that fasting does not fit your routine.

“Pay attention to what you’re feeding your body,” says Alyssa. “You can eat whatever you want during intermittent fasting, but you should still fuel it with good food that will make you feel healthy and strong.”

3 — Low blood sugar levels

Nausea, headaches, and dizziness during intermittent fasting may indicate that your blood sugar levels are low — which is especially dangerous for people who suffer from diabetes or other issues with insulin and thyroid.

Nutritionist Audrey Fleck further adds that skipping breakfast can particularly affect your blood sugar levels. “Starting your morning on an empty stomach can disrupt the rest of your day and set your body up for intense cravings later on,” the magazine explains.

4 — Constipation

“Any diet can cause stomach pain if you’re not consuming enough liquids, vitamins, proteins, or fibers,” says Alyssa, emphasizing the importance of staying hydrated throughout the day.

If you don’t hydrate enough during a fasting period, your intestines may stop functioning as they should.


Long-Term Dangerous Side Effects of Intermittent Fasting

1 — Obsession with Food

Any kind of restrictive diet can alter your relationship with food. According to Alyssa, while some people become extremely strict regarding intermittent fasting, others may become obsessed with the number of calories they consume.

Excessively worrying about the quality and quantity of what you eat daily can lead to orthorexia, a type of eating disorder. In this context, Audrey emphasizes that following an intermittent fasting plan is not recommended for people with a history of eating disorders.

2 — Hair Loss

Sudden weight loss or the loss of nutrients like vitamin B can lead to hair loss, as Alyssa explains.

And although following an intermittent fasting plan doesn’t necessarily lead to nutrient loss, it can be challenging to consume everything you need when you only eat for a few hours of the day.

3 — Changes in Your Menstrual Cycle

Another negative side effect of sudden weight loss is changes—like slowdown or complete stop—in a woman’s menstrual cycle. Therefore, ensure that your body continues to receive all the nutrients and calories it needs, even if you’re happy with your weight loss.

4 — Unhealthy Diet

Going a long time without eating can lead you to make poor choices during your calorie intake period. “The main concern is triggering binge eating behavior because you might be so hungry that you end up consuming 5,000 calories and exceeding your daily amount,” points out weight loss doctor and personal trainer Charlie Seltzer.

If you identify with this, it might be better to speak with a nutritionist to start a diet that doesn’t force you to restrict your eating hours.

5 — Sleep Disorders

Research published in the journal “Nature and Science of Sleep” indicates evidence that daytime intermittent fasting causes a decrease in REM sleep. REM sleep is associated with health benefits such as improved memory, cognitive processing, and concentration.

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