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Why Fasting Makes You Irritable and Angry

author avatar Dr. Eric Berg 06/27/2021


Do you get angry or irritable while fasting? This is why.


0:00 Why does fasting make me irritable?

1:50 Tips for irritability when fasting

Today we’re going to talk about why you might feel angry or irritable when intermittent fasting and what to do about it.

Your body runs off of three main types of fuel. There is sugar, ketones, and fatty acids. When someone lowers their carbs and sugars and starts producing ketones, they’re only running on about 40% ketones. About 60% of their fuel is fatty acids.

If you have a history of long-term insulin resistance, it will take a while for your body to become more flexible in this transition to burning ketones and fatty acids. During this transition process, you could feel angry or irritable when fasting. You might also have a low tolerance to stress.

Insulin resistance makes it difficult to get glucose into the cell because you need insulin to absorb glucose. When you go on a low-carb, low-sugar diet, you’re really low on glucose, and you’re dependent on ketones and fatty acids.

The problem is that your brain is the only organ that can’t use fatty acids. It can only use ketones and glucose. But, if you haven’t fully switched over to running on ketones and fatty acids yet, your brain and mood can suffer.

Tips for irritability when fasting:

1. Give it time for your body to fully adapt

2. Add more ketones to your diet during the adaptation phase (MCT oil or exogenous ketones)

This transition is temporary. Don’t give up, and eventually, you’ll feel really good while doing fasting and the keto diet.

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