Home /

Feeling Tired on Keto? 6 Reasons Why

Feeling Tired on Keto? 6 Reasons Why 

The ketogenic, or “keto,” diet is one of the most popular diets for those looking to change their bodies by losing fat, adding muscle or improving overall health.


What exactly is the keto diet? Are there any side effects? Is it normal to feel especially tired or exhausted after starting the keto diet?

What is the ketogenic diet?

A ketogenic diet is a low carbohydrate, high fat and moderate protein diet that centers on the idea of reaching a metabolic state called ketosis. In ketosis, the body is said to increase its efficiency at burning fat for energy. Its premise is allowing the body to use fat for fuel, which is then converted into ketones, as a primary fuel source. The keto diet is often compared to the Atkins diet; however, the two diets differ in their approach to fat intake. (The keto diet puts more emphasis on eating healthful fats than the Atkins diet.)


There are many different ways to “go keto,” but all versions share the common aspect of carbohydrate restriction. Generally, people following a keto diet reduce their carbohydrate intake to less than 50 grams a day. To put that into perspective, many people who are not following a ketogenic diet consume upwards of 225-325 grams of carbohydrates in their normal diet.


The general breakdown of calories per day on a ketogenic diet is as follows: 70-80% of calories from fat, 5-10% of calories from carbohydrates and 10-20% of calories from protein. Unlike many diets that encourage a more drastic increase in protein consumption, the keto diet limits protein intake to a moderate amount, as too much protein is thought to prevent ketosis.


The ketogenic diet has been linked to numerous benefits, including fat loss, reduced blood sugar levels, heart disease risk prevention and diabetes management. According to a 2017 article published by Harvard Medical School, there is solid evidence showing that a ketogenic diet reduces seizures in children, sometimes as effectively as medication. Because of these neuroprotective effects, it leads researchers to believe there could be possible benefits for other brain disorders like Parkinson’s, Alzheimer’s, multiple sclerosis, sleep disorders, autism and brain cancer. People with type-2 diabetes and other blood sugar issues also may benefit from the keto diet’s low carbohydrate intake, as it’s easier to manage insulin levels and blood sugar levels when carbohydrate intake is under control.

Why am I exhausted on the keto diet? The keto flu and other side effects

While many people experience benefits and positive results from going keto, there are some downsides and negative side effects of the keto diet. A common complaint is that dieters feel especially exhausted on the keto diet. 


There are a few reasons why dieters might feel so tired on the keto diet:

  1. They’re experiencing the keto flu. Some people get what’s known as the "keto flu" as their body adjusts to much lower amounts of carbohydrates. The keto flu usually occurs in the first week of starting the keto diet and involves headaches, fatigue, tiredness and nausea. Thankfully, keto flu symptoms are typically short-term and should eventually go away on their own.

  2. They’re having intense cravings for grains and other carbohydrate foods. If you restrict carbs, you will most likely feel tired or lethargic initially as you experience your first cravings for whole grains and other carbohydrate foods. 

  3. They’re not getting enough calories. Sometimes people associate the word “diet” with “low calorie.” The keto diet requires dieters to consume enough calories to maintain their energy. Undereating on the keto diet reduces your body’s production of thyroxine and other energy hormones, and consuming too few calories can even send your body into “starvation mode” over time. If you’re feeling low energy on the keto diet, eating a few more calories can help boost your energy levels and fight fatigue.

  4. They’re not getting enough fat in their diets. When on the keto diet, the vast majority of your energy comes from fat calories in the form of stored body fat as well as dietary fats that you eat. Just like some people associate the word “diet” with “low calorie,” some people also associate the word “diet” with “low fat.” What happens when you avoid fats — even healthy fats — on the ketogenic diet? Your body is short on its primary source of energy. With insufficient fuel in the form of fats, people can feel exhausted or fatigued on keto.

  5. They’re not eating regularly. Your meal schedule can also affect your energy levels — especially if you’re just starting keto. Eating regularly is one of the best ways to provide plenty of energy for the body. Keto dieters should have at least three meals and a few snacks a day, ideally spreading their meals and snacks evenly throughout the day to keep energy levels high throughout the entire day and avoid any mid-morning, afternoon or evening slumps. If you’re not used to the keto diet, combining the keto diet with intermittent fasting could cause energy depletion. 

  6. They’re not moving enough. If you're feeling tired on keto, you might not be getting enough exercise or movement throughout your day. It can be hard to work out when you’re eating differently, especially if you’re feeling tired or experiencing the keto flu; however, it’s important to build up to a regular workout schedule. Your routine should include a combination of weight training and cardio, with the goal of exercising at least 3-5 times a week. Frequently altering workout lengths and intensity can also help improve energy.


Because the ketogenic diet is high in fat, people also experience an increased risk of other health consequences such as high blood pressure, high cholesterol, heart disease and stroke — both immediately and down the line. People who are at higher risk of cardiovascular disease or have a family history of heart disease or similar conditions may want to avoid keto or other low-carb diets. 


Finally, the rigidness of this way of eating can also be a negative aspect of the keto diet: Because of the high fat and the carb restriction, the ketogenic diet can be difficult to follow for an extended period of time. 

Tips for avoiding the keto flu and getting enough protein and fat in your low-carb diet (without affecting weight loss)

Remember: Keto is a moderate protein diet, not a high protein diet. Tracking your protein and fats is equally as important on a ketogenic diet as tracking your carbs, because maintaining the state of ketosis depends on depriving the body of one macronutrient (carbs) while amping up the intake of another macronutrient (fat). Since carbs are so important to human functioning, this requires sufficient levels of fats and protein to offset the energy imbalance.


To better avoid the keto flu and keep your energy up while on the keto diet, make sure your diet is filled with healthy protein and fat sources. The key word here is “healthy.” Keto dieters can fall victim to “dirty keto” — a version of the keto diet that allows for highly processed and packaged foods. Dirty keto is popular among individuals who want to achieve ketosis without giving up greasy fast foods or spending the time to prep clean keto meals. This version of keto promises weight loss and fat burning with the freedom to eat anything you want, minus breads, fruits, sugars and sweets. That means bacon, cheese, pork rinds and fast foods without the buns or crust are acceptable “diet” foods; however, filling your diet with caloric foods that have no nutritional value will leave you feeling run down. Although dirty keto follows the same breakdown of fats, protein and carbs as regular keto, it matters where your macronutrients come from. A clean keto diet encourages you to eat vegetables, lean meats and quality fats like MCT oil — you’re still on track to lose weight, but you’ll feel much better and more energized eating a diet filled with healthy fat and protein sources instead of following a diet that centers on bunless double bacon cheeseburgers.


Below are some ideas for healthy fat and protein sources on keto:



For more ways to ensure you’re getting enough fat and protein in your keto diet while still maintaining weight loss, talk to your doctor, nutritionist or a registered dietitian.

Achieve ketosis without losing energy

Supplementing with protein powder can be a great way to give your body the protein it needs for more energy when following keto. Protein powder blends that are low in carbohydrates (1-2 grams) and contain 20-30 grams of protein are best for those on keto. While many protein shakes don’t contain much fat, you can easily add fat to your daily shake by making a smoothie that includes coconut oil or nuts.


Gainful offers a special blend of protein powder designed for people following a keto diet or those concerned about carb intake. It’s made with less than 1 gram of carbohydrates (your blend will be mostly all whey protein isolate, instead of the blend of different proteins), MCT oil and collagen, which is an important component of bone and skin health. Head here to take our quiz to find out which Gainful protein powder blend is right for you. Because Gainful is all about creating personalized formulas, we’ll take your keto diet plan, lifestyle and other dietary preferences into account when creating your blend. Then we’ll send you everything you need to start incorporating protein powder into your keto diet.


Also make sure you check out our Flavor Boosts. Because our protein powder is flavorless, our Flavor Boosts allow you to personalize your protein powder’s taste. You won’t have to buy a separate bag or tub of protein powder to get a burst of a specific flavor for your keto-friendly recipe — just add a Flavor Boost packet. Subscribers can choose from Strawberry Cream, Madagascar Vanilla, Rich Chocolate, Caffè Mocha, Cookies & Cream, Chocolate Peanut Butter, and Matcha Green Tea. 


(Yes, our Flavor Boosts are keto-approved.)


Gainful makes it easy to achieve ketosis, without sacrificing taste or energy. 


Disclaimer: Gainful does not necessarily advocate for the ketogenic diet for our customers. There is still conflicting research as to the nutritional effectiveness of following this diet. We recognize that what works in terms of diet for one person may or may not work for another. We encourage our customers to consult with a physician or dietitian before starting any new diet plan.

These statements have not been evaluated by the Food and Drug Administration.
This product is not intended to diagnose, treat, cure or prevent any disease.

6 West 18th St, #10F
New York, NY 10011