Your friend went keto and felt amazing. But whenever you try to keto, you feel nauseous, fatigued, and just plain awful.
What’s going on? How could a keto diet make you tired?
You went on a keto diet to improve your fatigue. But now you’re more tired than before you started. Sound familiar? I see this phenomenon happen regularly. It’s very common in someone just starting out with a ketogenic diet. Fortunately, it’s a relatively easy fix.
There are three specific points you need to be acutely aware of when you start a ketogenic diet. Be mindful of these and you’ll avoid the fatigue. And no, it’s not the keto flu that’s causing your fatigue. Read on to find out why your fatigue increased on a ketogenic diet.
Your body comes equipped with two different ways to produce energy. It’s like you have both a diesel and gasoline engine inside. Running on glucose is analogous to the gasoline engine. It’s what most people run on. And for the most part, it works.
When you enter ketosis, you turn off the gasoline engine and start running on diesel. In ketosis, the diesel fuel is much more efficient at producing energy for your body with little effort and waste (especially when compared to the gasoline engine). But switching from burning gas to burning diesel isn’t always smooth.
Sometimes, you can feel worse on a keto diet. In this post, I’ll show you the top three reasons you feel blah on a ketogenic diet and how to easily fix them. That way, you’ll be well on your way to overcoming fatigue and reaping the energy production benefits of ketosis.
** Please note that I have laid these three reasons out in a specific order. Please move through them in sequential order. They are meant to build on top of each other. This ensures there are no gaps in your keto diet! **
1. Salt Intake
I’ve solved many keto flus with the simple addition of salt to the diet. And it’s not just my opinion that supports this. Research suggests that the addition of salt will help to lower the negative side-effects of getting your body fat adapted. (1)
If you’re feeling tired after starting a ketogenic diet, your first step should be to amp up your salt intake. Generously salt all your food to your preferred taste. If you’re still feeling tired, try adding one teaspoon of salt to the first glass of water you drink in the morning. If the thought of drinking salted water makes you gag, opt for 1 bouillon cube dissolved in water per day or 1-2 cups of bone broth (just make sure your bone broth is well salted).
Amping up your salt intake often gets rid of many of the keto-related side effects including:
- Muscle cramping
- Heart palpitations (the sensation of feeling your own heartbeat)
But sometimes low sodium (salt) is not the problem. If you’ve already tried increasing your salt intake and you’re not feeling any better, it’s time to look at step number two!
2. A low-carb but not quite ketogenic diet
I see this occur a lot with newly adopted keto diets. And I think it has to do with a lot of the misinformation found on the internet. Some sites will say restricting your net carbs to <50g will put you into ketosis. Others say <40g net carbs. And others say <20g is absolutely essential.
Here’s the deal, there is no perfect number. Each of you tolerates carbohydrates differently. Some of you can be in ketosis and eat 50 grams of carbs. For others, you’re going to have to be super strict and ensure your net carbs are always less than 20 grams per day. Stop sticking to generalities. Remember, you’re unique. What works for your friend might not work for you.
Your body does everything it can to be efficient. It takes fewer chemical reactions for your body to utilize glucose for fuel than it does for fat. So long as you’re consuming enough glucose, your body will use that for energy. In order to successfully enter ketosis, you need to restrict carbohydrates. Doing this depletes your body’s glucose stores and forces it to use fat for fuel.
If you’re eating more carbohydrates than your body tolerates, you’re not going to enter ketosis. Instead, you’ll be in a low-carb but not quite ketogenic state. And for all you females out there, this is not a comfortable place to be. It’s a common cause of fatigue, hormonal fluctuations, and decreased athletic performance.
To ensure you’re in ketosis, restrict your daily net carbohydrate intake to less than twenty grams per day. I’ve found that at this level, everyone enters ketosis. When you start going above twenty grams, some of you will inevitably exit ketosis and enter the realm of low carbohydrate (but not ketogenic) diets. This is not where you want to be!
I strongly encourage to track your macros with an app like cronometer or my fitness pal when you’re getting started. Twenty grams of carbohydrates is not many. And getting nearly 80% of your daily calories from fat is far from intuitive. For the first few weeks, use a tool to objectively measure and track your progress. Do not go on how you feel. How you feel is highly variable. When you’re starting a ketogenic diet, you need to be objective!
I recommend you avoid carbohydrate re-feeds or any sort of deviation from the keto diet for the first six weeks. These six weeks are all about getting you fat (keto) adapted. It’s likely your body has run on glucose for the majority of your life. Getting your fat burning machinery well calibrated will take some time. So, for the first six weeks, be super strict with your keto diet.
This should help you improve your fatigue levels. But if both steps one and two still didn’t provide the energy boost you were looking for, read on to step number three.
3. The accidental low-calorie diet
Of all the potential reasons you feel tired on a ketogenic diet, this one is by far the most insidious. I see it happen time and time again in the clinic. And it’s an honest mistake. It’s happened to me on more than one occasion.
When you’re in ketosis, the hunger signals that arrive at your brain are not nearly as loud as they are when you’re burning glucose for fuel. You’ve been hangry before, right? When you’re hangry, your brain is screaming at you to eat. You’re absolutely miserable. It’s challenging to stand yourself and anyone around you. The world is irritating when you’re hangry. This is a strong hunger signal.
But when you’re in ketosis, the hunger signal can be a gentle whisper. This makes it really easy to ignore. The reason the ketogenic hunger signal is so subtle is that your brain (and other energy consuming machinery in your body) have constant access to your body fat. All of us carry at least some body fat. So, there’s always calories to be had.
When you burn glucose for fuel, you’re dependent on eating to get enough energy. But when you’re in ketosis, your body can always steal some energy from your fat stores. That’s why the hunger signals from ketosis can feel more like suggestions than actual impulses.
Since these reminders to eat are both infrequent and subtle it’s not at all uncommon to be extremely deficient in calories and not be hungry. I had a patient complain of intense fatigue and lethargy shortly after starting a keto diet. When we calculated her daily calories, she had been in an almost 1500 calorie deficit every day for the past two weeks! And she wasn’t the least bit hungry. At that level of daily calorie restriction, it’s little wonder she was exhausted!
For reference, a healthy weight loss strategy (depending on your height, weight, and activity level) is to decrease your daily calories by about 500. This should result in approximately one pound of weight loss each week. The patient I referenced earlier was nearly 3x that amount every day!
Lots of websites suggest that while on a keto diet, you eat when you’re hungry and eat until you are full. I love this adage. I think it helps to create a healthy relationship with your food. But intuitive eating can make you fatigued when you’re new to keto.
To ensure your daily calorie needs are within healthy ranges, I strongly encourage you to track. I know, counting calories is awful, painful, neurotic, etc. It is all of these things. But it simply has to be done in the beginning. Otherwise, you may end up on an accidental low-calorie diet! Once you’ve been on keto for a couple of months, you can then move towards intuitive eating.
How to calculate your daily caloric needs
To calculate your daily calorie needs, I recommend using a formula like the Harris-Benedict equation. This will give you a rough approximation of your basal metabolic rate (BMR). Your BMR is the number of calories your body burns in a day – based on your exercise habits and movement levels throughout a normal day. If you eat close to this number, you’ll maintain your current weight.
If you’re following a keto diet to improve your energy but also want to lose weight, I don’t recommend you cut your daily calories any more than 500 calories less than your daily BMR. This should keep your energy levels high and result in a weight loss of approximately one pound per week.
If you don’t need to lose weight, try to keep your calories close to your BMR. This becomes very important for those of you who are quite lean. There’s just not enough extra adipose tissue on your body to use as fuel.
If you’re practicing intermittent fasting, you’ll need to be mindful of your total calories consumed in a week. On fasting days, you’ll be well below your BMR level of calories. That is just fine so long as you make it up on non-fasting days (eating more than your BMR suggests). For some of you, intermittent fasting is only going to decrease your energy. If you don’t feel good fasting, don’t do it.
After you’ve got a rough idea of how many calories you need in a typical day/week, you can stop with the counting. Move back towards intuitive eating – eat when you’re hungry. Eat until you are full. But only do this after you’re confident about how much you need to eat in a typical day/week.
Ok, now you know how to avoid fatigue on a keto diet. Now, I want to hear from you!
What strategies gave you more energy on a keto diet?