Do Detox Diets Make You Tired?

There is little doubt that there are numerous, short term side effects to undertaking a detox diet. Depending on a number of factors, these side effects can be debilitating (headaches, nausea), or mildly annoying (bloating, fatigue). And it is the factors that influence one of those side-effects that we are going to discuss in this article.

Specifically, we are talking about fatigue. Often the perception that a detox diet will leave you feeling tired and lacking in energy has been used as an excuse to avoid the process. If you are fatigued and generally lacking in energy during the diet, how are you supposed to function in day to day life, and secondly, how is that meant to be good for you?

In order to address these questions we need to understand why you may experience feelings of drowsiness during the diet, then move on to possible solutions to help you deal with that particular side effect.


Will a detox diet make you tired? The short answer is almost certainly yes.

Like all the other symptoms you may experience, the level of fatigue you will experience may vary, but the factors that cause it will almost always be present. There are a number of things that lead to feelings of fatigue during a detox diet, however the most prevalent is calorie intake.

How Many Calories Are Enough?

Let’s start by drawing a line under how many calories a person needs to eat on average to function.

The scientific consensus is that on average, adult women need to consume around 2,000 calories a day to maintain their weight, while adult males need around 2,500. (2) In order to manage steady weight loss of around 1 pound per week, both men and women need to reduce their calorie intake by around 500 calories per day.

Those numbers obviously assume an average level of daily activity. If the adult in question has a highly active lifestyle, these intake amounts will be insufficient, and will need to be supplemented to compensate for the extra exercise.

That said, how does one conceptualize 2,000 calories in actual food? These images can be a very helpful tool when we are trying to form a mental picture of what makes up a 2,000 calorie diet. Sixteen apples, eighteen bananas, three hamburgers. Not all together, of course, each category by itself.

So as you can see, 2,000 calories isn’t a lot, and 2,500 calories isn’t a lot more: think twenty apples instead of sixteen.

Calorie Intake During a Detox Diet

Most detox diets however, are based around a reduction in your calorie intake due largely to a change in diet. We know that a diet of 1500 calories a day will result in steady, sustainable weight loss. Consuming far less than that, say 1000 calories, will result in feelings of fatigue and sleepiness, quite simply because 1,500 calories is just not enough to adequately fuel the human body, let alone an active one. (3)

When shifting to a diet comprised primarily of juice, or fresh fruit and vegetables, it is quite easy to feel like you are eating a lot due to the food volume. However, the foods that make up these diets are generally very low in calories, which is fine because that’s how they are supposed to be.

However, you will find that you are making the decision to move to a detox diet, you are generally shifting away from a diet that is calorie dense, which may take some adjusting to since your body is used to overfeeding, not underfeeding.

Calorie Deficiency

The calorie deficiency therefore leaves you feeling lacking in energy, even though the foods you are now consuming are full of nutrients. You are suddenly getting the right type of calories, but just not enough of them. I mean, who is really going to be able to eat eighteen bananas in a day? So overall, you’ll be feeling ‘better’ (as in healthier), just tired.

Calorie Sources

Another thing that is likely to change in a detox diet relates to the types of foods you will be eating. Detox diets tend to be low in artificial sugars, and caffeine. These are two sources of short term energy that can boost your level of alertness. (3)

While there are a number of detox teas that contain caffeine sources, these are generally present at a level that will stimulate your metabolism, rather than give you the energy boost that is usually associated with the morning, or mid morning cup of coffee.

Similarly, while outside of a detox regimen, the mid-afternoon energy-sag can be combated with a sugary treat or a hit of chocolate (for that short term energy buzz). A true detox diet however, avoids processed sugars.


Another major contributor to feelings of fatigue and drowsiness during a detox diet is the substantial workload that is being laden onto your body (4) The diet is designed to incite the body to deal with a build up of toxins. A true detox diet is intended to stimulate the natural workings of the liver, kidneys and bowel, which are your body’s main filters.

Fundamentally, a detox diet promotes the filtering of toxins out of your blood and cells, including built-up medicines, synthetic chemicals, heavy metals and ammonia. The liver is the primary processing centre for this function, and it generally delivers the toxins into your bowel so they can be expelled. (5) This is one of the causes of the feelings of nausea that are generally related to the early periods of a detox.

It is the body’s natural function to filter and remove these substances from your blood, and in general, and if you have embraced a healthy lifestyle and diet, then intensive detoxing is usually not necessary. If, however, your diet is full of processed foods and chemicals a detox may occasionally be necessary. (6)

The detox diet, therefore, is generally low in calories, and asks your body to work harder on an internal process than it usually would. The heightened workload, matched with the reduced fuel load naturally leads to the feelings of fatigue that are often symptomatic of these types of diets, which is why the diet is intended to be short term (7-10 days only).

What To Do?

If we accept that a detox diet is going to make you tired, that doesn’t mean you should avoid the detox altogether.

An unhealthy diet rich in high calorie, processed foods will leave you feeling sluggish and heavy as well. The net result of a detox, while initially unpleasant, is generally an improvement in your overall wellbeing and an increase in your energy levels. It may be hard at first, but if you persist it’s worth it.

So the challenge shifts to learning how to deal with the fatigue, rather than avoiding the detox. Fortunately, dealing with fatigue isn’t rocket science.

  • Make sure you are getting enough sleep. Plan for at least 8 hours a night.
  • Take naps. If you are feeling lethargic during the day, make the time to nap. This gives your body permission to recover from the energy drain, and has been proven to increase concentration, and improve mood.
  • Reduce your exercise routines. You are running on less fuel than normal, and your body is working very hard on internal processes. It isn’t necessary or helpful to then stress your body with a hard core exercise routine. Stick to moderate exercise, and give yourself permission to skip a session entirely if needed.


Dealing with the fatigue and tiredness associated with detoxing is easy, and the process is fundamentally beneficial to your overall health and wellbeing. Don’t let the perceived burden of fatigue discourage you.


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