Low Carb

Why am I so Tired on a Low Carb Diet?

Max Carmody, MSc

Low Carb diet plans can make people tired due to electrolyte loss, water loss, and fluctuations in blood glucose. You can feel tired from not eating enough calories or being dehydrated.

Low Carb Diets and Keto Diets

On a low carb diet you limit your carbohydrates, especially those found in things like sugars, pasta, and breads. It is generally high in protein and fat. Sometimes you also avoid starchy vegetables and most fruits. Starchy vegetables are things like corn, potatoes, and beets. For a standard low carb diet, you are generally eating anywhere from 50 to 130 or so carbs a day. There are many different diets based on cutting carbs, such as the Atkins diet, keto diet, paleo diet, whole30 diet, dukan diet, and the south beach diet. 

Keto diets are very popular right now, so we will discuss them. A keto diet is essentially a low carb diet. But on the keto diet, you usually eat fewer carbs than you do on most other forms of low carb diets, and more fat. On a keto diet you generally consume between 20 and 50 carbs a day. Reducing carbs in this manner puts your body into a state called ketosis. When ketosis occurs, your body becomes very efficient at burning fat for energy. Your body turns fat into ketones in your liver, which may supply fat for the brain. Keto diets can cause great reductions in insulin and blood sugar levels.

Low carb diets do have some pros. They can reduce your appetite overall, a greater proportion of your weight loss comes from the abdomen (which is considered “toxic” fat), triglycerides, which are fat molecules, drop drastically. There are increased levels of “good” cholesterol, reduced blood sugar and insulin levels, they may lower blood pressure, they can improve “bad” cholesterol levels, and they are good for certain brain conditions. If you want to find out more about whether a low carb diet is a good diet, you can find an article here that I wrote on the topic.

Why am I tired?

In addition to the pros, there are a few cons. Low carb diets can make you tired. Low carb diets don’t always make you tired. They have never made me tired. But they do have the potential to do so. This is usually temporary, and goes away within the first few weeks of the low carb diet. 

Fatigue can occur on it’s own, or together with something called “keto flu”. Keto flu is a temporary condition that can produce symptoms like dizziness, constipation, lightheadedness, and tiredness. This brief period that can occur at the start of a low carb diet is sometimes called carbohydrate withdrawal. 

Mild side effects associated with a low carb diet tend to pass very quickly. They usually go away by the 4th day you’re on a low carb diet. These side effects are usually due to electrolyte loss, water loss, and fluctuations in blood glucose. If these side effects are not going away for you, you may want to find out if you’re not a person who should be on a low carb diet, I wrote an article that you can find here on the topic.

You may not be eating enough calories. Some people assume that any diet must be very low calorie, and are not eating enough. You may also not be eating enough fat. Since your body is deprived of carbs, you need to make some of that up with fats. After starting a new diet, you may not be eating regularly, and this could make you quite tired. 

It is possible that you are so tired because you are dehydrated. When we are eating more carbs, our bodies convert excess carbs to glycogen that are stored up for energy. Glycogen holds onto water, and can make you feel bloated after a high carb meal. As we eat fewer carbs, our bodies use up the rest of the glycogen stores for energy. This can result in excess water loss and frequent urination. 

When you lose water, you will also lose electrolytes, like magnesium, potassium, and sodium. If these things are improperly balanced it can lead to fatigue.

How to Feel Less Tired

Fortunately, we can take matters into our own hands and do some things to feel less tired. If your fatigue is particularly bad and is not abating, you might want to consider back pedaling a bit, and easing yourself into a low carb diet. You can just eliminate sugary sweets at first, and then baked goods, then slowly, things like bread and potatoes.

If you are determined to go all in right away, there are still some things you can do. You can eat more fat. You can eat more regularly, and make sure that you are not skipping meals. This might mean not trying intermittent fasting at the same time as your low carb diet. You can eat more healthy and clean, by avoiding things like artificial sweeteners and other unnatural foods. 

If you are on a very strict, extremely low carb keto plan, you may want to add more carbs and switch to a more moderate carb plan.

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