Side Effects You Should Know Before Starting To Intermittent Fast

Harvard Health Publishing reports that over the past few years, intermittent fasting has quickly gained momentum. Thanks to its promises of enhanced health and weight control, it's easy to see why. The concept is that it's more achievable to significantly reduce calories for part of the week — or to have a limited 'eating window' each day — than it is to reduce calories on a daily basis. 

The benefits of intermittent fasting are constantly raved about. However, despite all of the talk about different fasting schedules and how you can combine intermittent fasting with other diets, like the popular keto diet, there's also an often overlooked issue: the side effects that can come hand in hand with intermittent fasting. The fact is that any diet — no matter how many people rave about it — can cause side effects for some people. What works for one person doesn't always work for others. 

What causes issues with intermittent fasting? The reality is that if you're failing to consume enough calories or nutrients during fasting periods, it could lead to a number of uncomfortable side effects. If you're not getting on with fasting, it could be as simple as you're failing to consume enough calories or enough nutrients. The tricky part is that as there are no formal guidelines in relation to the number of calories you should consume when fasting — or the types of foods that you should be eating in non-fasting hours.

You might become 'hangry'

The term "hangry" might not be a real word, but it's certainly a very real feeling. It's the combination of being hungry and angry at the same time, caused by lack of food. Not being able to eat when your body is telling you it's hungry — such as when you're fasting — can cause you to become irritable and grumpy.

According to Harvard Health Publishing, not everyone is designed to fast. If you're one of those people who becomes irritable and grouchy when you're unable to eat, you might find that fasting isn't for you. This is especially true if being hangry inhibits your ability to function normally and continue with your day. Remember that Snickers commercial and how "you're not you when you're hungry?" Well, that's a clear example of the impact of hanger right there. For some of us, when we're hungry — or hangry — we turn into unrecognizable versions of ourselves, and the truth is, it's not pretty.

As recommended by registered dietician Kathy McManus, easing yourself into fasting may help. She told Harvard Health Publishing that dieters can "[s]lowly reduce the time window for eating, over a period of several months."

You may experience brain fog

When it's done right, intermittent fasting can offer some results. The issue is that there's a rather large margin for error. Have you ever found yourself sitting at work and struggling to focus only to realize that you skipped breakfast? As a lot of people who do intermittent fasting tend to not eat breakfast and fast at the start of the day, if you're someone who finds their mind clouded if you miss breakfast, intermittent fasting might not be the right fit for you or this might be a sign that you're not fasting the right way. This is especially true if you find yourself making silly mistakes due to your brain fog.

If you fail to eat the right foods during your non-fasting periods, you may not be intaking the necessary calories and nutrients that your mind and body need to function. Be mindful of what you're putting into your body. While intermittent fasting allows you to eat what you want, it's important that you're fueling your body with foods that are high in nutritional value.

As Women's Health reports, when intermittent fasting, it's also important to determine which method works best for you. Alyssa Koens , the lead registered dietician of weight loss coaching company Profile Sanford, notes that it's "important to figure out which style of IF works for you, whether that's a shorter versus longer fasting window or only doing it so many days per week."

Your blood sugar might drop

Feeling a little funny while fasting? It might be a side effect of restricting your calorie and nutrient intake. If you notice that you're not feeling well or are lacking energy and feeling lethargic while intermittent fasting, this could be a sign that your body isn't coping well with the change in diet. For some people, intermittent fasting can cause blood sugar levels to dip, causing feelings of nausea, headaches, and even dizziness or fainting spells, per Harvard Health Publishing.

It's for this reason that intermittent fasting isn't suitable for people with certain health conditions, like diabetes or thyroid-related health problems. This is because intermittent fasting can cause hypoglycemia, a potentially serious condition for anyone living with insulin dependency or issues, or for anyone with thyroid problems, per Women's Health.

While intermittent fasting can offer a number of weight loss benefits and is a popular means of shedding excess weight, like all diets, it can come with a range of side effects.