Why am I exhausted on the Keto diet? - ketolibriyum

Why am I exhausted on the Keto diet?


The keto diet is a high-fat, low-carbohydrate diet, which is designed to bring about a state known as ketosis. Ketosis makes the body burn fat faster by using fat as fuel. More and more people are embracing the keto diet, and in 2020, ‘keto’ was the most common food-related search term on Google, accounting for over 25 million searches globally. 

Switching to the keto diet requires the body to adapt and adjust, and one of the most common side effects is tiredness. If you feel exhausted on the keto diet, you’re not alone. In this guide, we’ll delve deeper into the diet, explaining why individuals who modify their weekly menu to reap the rewards of the keto diet may experience a period of fatigue and lethargy. 


Why am I exhausted on the keto diet?

Research suggests that there are significant advantages to following a healthy keto diet, but there are also side effects and disadvantages, particularly during the transition stage when the body is adapting to the new diet. There are several reasons why people feel tired on the keto diet. Here are the most common explanations:

1. Keto flu

Some people develop symptoms known as the keto flu when they change their diet. The keto flu is associated with adjusting the diet to lower carbohydrate intake. In most cases, the keto program involves reducing carbohydrate consumption to less than 50 grams per day. To provide context, most people who have a regular diet consume around 200-300 grams of carbohydrates per day. It can take a while to get used to significant reductions in carbohydrate intake, and some people develop flu-like symptoms, usually in the first week of the new diet. Symptoms include:

  • Headaches
  • Nausea
  • Tiredness
  • Fatigue and lethargy

It is common to experience these symptoms and to go through a period of feeling generally unwell after switching to a new diet. In the vast majority of cases, individuals will not need treatment for keto flu and they will start to notice symptoms easing after a few days. 

If you do develop keto flu after starting the keto diet, it’s advisable to look after yourself by making sure you get enough rest, staying hydrated and exercising regularly. It can also be beneficial to explore electrolyte supplements. 

2. Dehydration

Why am I exhausted on the Keto diet

Dehydration is a common cause of fatigue and chronic tiredness when following any diet. Regardless of what you are eating, it is essential to ensure that you take enough fluids on board. Dehydration occurs when the body lacks water, and it can contribute to a host of unpleasant and potentially dangerous symptoms, including brain fog, exhaustion, confusion, muscle pain and headaches.

Dehydration can occur more frequently in people who follow the keto diet. This is because the keto diet is low in carbohydrates. When you consume foods that contain carbohydrates, the body reacts and the pancreas produces insulin to regulate sugar levels. When your carbohydrate consumption is low, insulin levels remain stable, as your body doesn’t have to act to control blood sugar levels. Insulin is usually associated with maintaining healthy blood glucose levels, but it also has additional functions, including encouraging the kidneys to keep hold of key minerals and electrolytes, including potassium, sodium and magnesium. When you follow a low-carbohydrate diet, the kidneys excrete a lot of water, as well as minerals and electrolytes. This means that it may be advisable to take supplements and to ensure that you drink plenty of water. If you lose electrolytes and you don’t replace them, there is a risk of dehydration. 

If you are starting the keto diet, be mindful of the need to stay hydrated and replenish lost electrolytes. It can take a while to determine how much extra fluid or salt you need. It’s beneficial to seek advice if you’re unsure which supplements to use. 

Common symptoms to look out for include:

  • Increased tiredness, especially during the day
  • Dry skin and hair
  • Dark, odorous urine
  • Feeling dizzy or light-headed
  • Muscle pain
  • Headaches
  • Urinating less frequently

3. Poor quality food

Why am I exhausted on the Keto diet

There are many options when it comes to compiling a menu when switching to the keto diet. The problem is that not all keto diets are created equal and there are instances when people who try to follow a keto diet eat a lot of unhealthy foods that don’t offer nutritional value. The primary aim of the keto diet is to change the way the body processes and burns fat and to prioritise fat as fuel over carbohydrates. While a keto diet, which is high in fat and low in carbohydrates, can offer significant benefits for health and wellbeing, it is possible for individuals to choose low-quality foods. If you’re eating foods that lack essential nutrients, sometimes known as ‘dirty keto’ foods, you may find that you feel tired and you’re prone to exhaustion. 

To combat fatigue and boost your health, try to follow healthy keto diet plans and eat clean whenever possible. Fast food and processed foods may meet keto macros, but these foods often contain additives and lack minerals and vitamins. In the long term, eating the wrong foods can contribute to deficiencies, imbalances in essential oils and fats and underlying health issues that could exacerbate fatigue. 

Examples of foods to consider adding to your menu include:

  • Seafood and fish
  • Fibre-rich, low-carb vegetables, including broccoli, kale, peppers, zucchini, cabbage and asparagus
  • Cheese
  • Avocados
  • Poultry and meat
  • Eggs
  • Cottage cheese
  • Natural yoghurt
  • Nuts and seeds
  • Olive oil
  • Butter
  • Low-carb berries, such as strawberries and raspberries
  • Shirataki noodles

4. Excessive exercise

Exercise offers a raft of benefits for adults of all ages, but there is a risk of overtraining and working out excessively. If you expend too much energy and push yourself too hard, you may find that you feel exhausted, especially if you are in the early stages of the keto diet and your body is still adjusting. Regular exercise can energise you and lift your mood, but it’s important to ensure that you get enough rest and that you listen to your body. If you feel tired, take a break or opt for a low-intensity activity, such as walking or swimming. Exercising excessively will leave your body craving fuel and it could also increase the risk of injury. 

Health experts recommend 150 minutes of moderate exercise per week. This can include everything from jogging and playing tennis or golf to hiking, trampolining or doing exercise classes, such as yoga, HIIT or spinning. 

If you exercise frequently, keep an eye on your body and monitor your energy levels and mood if you’re starting the keto diet. Some people find that they are able to continue as normal with their fitness regime when changing their diet, while others feel more tired during the first few days. If you do feel exhausted, keep moving but lower the intensity and take regular breaks. If you’re used to sprinting on the treadmill or going for long hikes or bike rides, for example, take a walk or a jog or shorten the distance until you feel stronger and more energetic.

5. Calorie deficit

Why am I exhausted on the Keto diet

In the most basic terms, weight loss occurs when you burn more calories than you consume. If you have a calorie deficit frequently, you will lose weight. One of the main reasons people feel tired when they are on the keto diet is a recurrent calorie deficit, which means that the body needs more fuel. People often associate diets with low calorie intake. Reducing calorie consumption is beneficial for gradual, sustainable weight loss, but there is a risk of dipping too low in terms of daily calorie intake. On the keto diet, it is relatively easy to achieve and sustain a calorie deficit because your body burns more fat and you don’t tend to feel as hungry. This diet can also accelerate metabolism, meaning you burn more calories. 

If you are following the keto diet, it’s important to ensure that your calorie intake enables you to function properly and maintain good health. If you undereat and you restrict calorie intake too much, this can cause chronic fatigue, excessive weight loss and hormonal issues, particularly those related to thyroid activity. 

If you feel tired all the time when you’re on the keto diet, and you’re concerned that you’re not eating enough, try to increase your consumption of healthy fats and nutritious meals that will release energy relatively slowly to boost your energy levels. You might also benefit from eating more frequently during the day.

6. Not getting enough fats

The main focus of the keto diet is encouraging the body to utilise fats as fuel. If you’re not consuming carbohydrate-rich foods, and you’re not getting enough fat in your diet, your body won’t have a source of fuel and you’ll feel tired and sluggish. To adapt to ketosis and change the way your body digests food and produces energy, you need to ensure that you consume enough fats in your diet. There are different types of fats and some are better for you than others. Try to stick to healthy fats and choose high-quality, nutritious foods. 

7. Stress

Why am I exhausted on the Keto diet

Stress affects most of us at some point in our lives, and it can occur as a result of multiple causes, including pressure at work, financial issues, being too busy and changes in your environment or routine. Switching to the keto diet is a major shake-up for the body and it can exacerbate stress temporarily, contributing to physical and psychological symptoms, including fatigue, difficulty sleeping and hormonal imbalances, which affect your appetite and mood and may also cause anxiety, sweating and headaches. 


Tips to prevent exhaustion on the keto diet

It is common to experience tiredness during the first few days of the keto diet, but if you continue to feel exhausted, it’s wise to consider taking these steps:

  • Track your calorie intake: many people start the keto diet to lose weight. Reducing calorie intake will help you to shed extra pounds, but it’s critical to avoid going too low in terms of your daily calorie intake. If your body doesn’t get sufficient fuel, and you’re not eating enough, you’ll feel exhausted and you may be deficient in key nutrients, which will impact your health. 
  • Keep moving but avoid excessive exercise: exercise is beneficial for everyone, but there is a risk of going too far and pushing your body too hard. If you feel tired all the time and you’ve been doing intense workouts, it’s advisable to take a break, allow your body to rest and recover and opt for low-intensity activities.
  • Choose high-quality, nutritious foods: the keto diet is a high-fat diet but there are many different types of foods that fit within the high-fat category. Some are more nutritious than others. Ensure you get enough fat in your diet and opt for healthy, high-quality ingredients that will ensure you get the vitamins and minerals you need. 
  • Stay hydrated: dehydration is a common cause of fatigue. The risk of dehydration is higher on the keto diet because it is a low-carbohydrate plan. If you are on the keto diet, make sure you take enough fluid on board. You may need to increase your intake of water, especially if it is hot outside or you’re losing fluid due to sweating through exercise. 
  • Consider supplements: dehydration and switching to a low-carbohydrate diet can cause your body to lose electrolytes. If you are prone to fatigue and exhaustion, consider taking supplements. Ask for expert advice before buying supplements. 



The ketogenic diet has become increasingly popular, as people look for ways to lose weight and embrace a healthier lifestyle. It is common to experience tiredness during the first few days of the keto diet, but if exhaustion persists, there may be underlying reasons. Adjusting your diet and calorie intake, undertaking regular, moderate exercise, increasing fluid intake and replacing lost electrolytes can help to boost energy levels and prevent tiredness. 

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