Low-Carb Lunch: Are there sleep effects?

woman feeling tired sitting near the window


Carbohydrates are what everyone seems to be talking about these days. It is present everywhere, from fresh bread and pasta to sweet desserts and even healthy veggies and fruit. It is an important constituent of almost every delicious food we can think of. After all, carbs are made up of simple sugars which is why we tend to love and crave them so much. 

If you have been eating more carbs lately and seen your weight fluctuate towards the higher side, you may be feeling the need to start eating more mindfully. This means paying more attention to what and how much food you are eating. There are so many different diets and meal plans that are making their way around, that it can be very confusing which ones work and which ones don’t. One diet plan (or “lifestyle” as some like to call it) that has been very effective in helping people achieve their goals, is the popular complete ketogenic diet. 

Let’s take a quick look at what a keto diet is and how it works so effectively for people who need to lose a lot of weight. Then we can discuss why we may be feeling a little bit more tired after lunch while on this kind of diet and how we can get back to having a lot more energy in order to accomplish our afternoon tasks. Finally, we will learn about what happens when we are in ketosis.


The Ketogenic Diet

For those searching for a diet (way of life) that is relatively easy to begin, with results that are fairly quick and hugely rewarding, then the ketogenic (keto) diet may be a great choice for you. Basically, it is a diet in which you take in a high amount of fats, a low amount of carbohydrates, and a medium amount of protein. With this diet, your body obtains the energy from fats rather than carbs (chains of simple sugar molecules) which helps you lose weight. 

There have been many benefits of maintaining a ketogenic way of life. To name a few, it helps in weight loss, as well as aiding in skin problems like acne, helps in heart performance, reduces seizures, enhances brain function, and may even reduce the chances of getting cancer.

But the question is if it has all these benefits, why do some still feel sleepy after a lunch that’s low-carb?


a white plate full of food placed on a brown dining table

Photo by Louis Hansel @shotsoflouis


The Science Behind It

In general, most people generally feel sleepy after lunch (or any meal) because tryptophan, which is a chemical present in foods, is used by the body to create serotonin. Serotonin is a neurotransmitter that helps regulate sleep in our bodies. Sometimes, the foods we eat have more tryptophan (like turkey or eggs) which in turn increases the amount of serotonin released that ultimately increases one’s sleepiness. 

On average, for a non-keto diet adult, 45% to 65% of our daily calorie intake consists of carbohydrates. This is approximately 225 to 335 grams of food every day. On a keto diet plan, since the main energy source is from fats rather than carbs, the fat intake should be increased and the carb intake has to be reduced.

A standard keto diet nutrient formula states that about 70% of your food should be derived from fats, 20% from protein, and 10% from carbohydrates. This is a large discrepancy between non-keto and keto dieters and their carb daily intakes. 

The energy source switch is the problem. If you are used to loading your body up with carbs and then one day decide to go cold turkey and not eat any more carbs, your body is going to react. After all, removing the only energy source it has ever known and replacing it with another, will cause some type of change. And this decrease in carb and increase in fat consumption will mean that your body will start generating ketone bodies for fuel.


What are ketone bodies?

Glad you asked.

Removing carbs from your diet deprives your body of glucose as an energy source, so it begins to seek an alternative. It pushes the body into a state of ketosis where the liver produces ketones (the ketone bodies). They are the body’s byproducts of fat metabolism.

Your body is now breaking down fat instead of sugar. During this transition, the body uses up all the stored energy from sugar and may not yet be ready to have enzymes to break down fat. The energy drop you feel is as a result of the switch because your body is waiting for ketosis to set in.

This is another reason why you feel tired and sleepy after a low-carb lunch.


There’s Good News!

You aren’t going to feel this way forever.

Although there isn’t a standard period for the lethargic state to last, you can see a change in less than 10 days. For others, the struggle can last up to 6 weeks. So, be prepared. 

The only way to keep up with the changes is to maintain your energy level. Here are some ways you can achieve that:

a. Eat lots of alkaline foods and electrolyte-rich foods. Some good suggested sources are seaweed, avocado, non-starchy vegetables, nuts, and seeds. 

b. Ingest food sources that extract MCTs (medium-chain triglycerides) like oil organic coconut oil and palm kernel oil by the spoonful: Research has shown that MCT oils help to maintain energy levels because they are more easily absorbed by the body not requiring bile or pancreatic enzymes to be digested. They are transported right to the liver to be used as an immediate source of energy and not stored as body fat.


**Please note, it is recommended that you should discuss whether a ketogenic lifestyle is right for you with your doctor.