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Calorie Deficits and Insomnia: Here's Why and What to Do

by Dale Cudmore | Updated: Jun 28, 2021

While it seems that most people don’t have any problems, there are quite a few stories of people going on a calorie-restricted diet and developing sleep problems.

This can have a big effect on weight loss. Sleep deprivation leads to insulin resistance and weight gain, which may make the whole diet counterproductive (1). 

It can also affect mood negatively (i.e. people get “hangry”), which may lead to poorer eating decisions.

I dug into all the research I could find about calorie restriction and sleep quality to find out if calorie deficits cause insomnia.

Research About Calorie Deficits and Insomnia

I was a bit disappointed in the quality of research that I could find on this topic.

There are certainly studies on calorie restriction and sleep quality, but most only measure them after long time periods (since they’re more focused on weight loss).

Unfortunately, this means that there isn’t much data on what happens right after starting a diet. This is a shame, because there is evidence that diets like intermittent fasting can cause insomnia in the short-term, before leading to better sleep later.

The Size of the Deficit Appears to Matter

It’s clear that starvation-level calorie restriction causes sleep disturbances and a reduction in sleep in both animals and humans (2).

Other research also suggests that a large calorie deficit will also lead to sleep problems. Hunger can cause sleep problems for some people.

One study of overweight women measured the effects of reducing calories from approximately 9,000 per day to 3,000 (3). It found a significant increase in sleep onset latency (time to fall asleep) and a reduction in slow wave sleep (deep sleep).

Other studies have also found that calorie restriction of smaller amounts also causes a reduction of slow wave sleep, so that’s not necessarily a problem. It may just mean that you need less if you’re eating less.

Here’s where things get interesting...

Another study of calorie restriction in obese men had a control group (no diet) and calorie restricted group. The restricted group gradually decreased their daily calorie deficit to approximately 500 calories (4). After 6 months, the diet group had a shorter sleep onset latency, longer total sleep time, better sleep efficiency, and fewer depressive symptoms.

Similarly, a 3 month trial with subjects on a similar calorie deficit found (5):

A significant reduction in body weight, BMI, body fat percentage and depression

There were no significant changes in sleep quality and stress level between the groups as a result of the intervention.

Finally, in a group of both men and women, calorie restriction had some positive effects on general health and sleep duration at month 12 (6). As a reminder, we don’t know what happened shortly after the study started, perhaps sleep got worse before it got better.

SummaryIn general, research seems to show that calorie restriction improves sleep quality long term, likely due to weight loss. However, there’s enough evidence to think that a huge calorie deficit can lead to sleep troubles, especially short term.

Why Might Diets Cause Sleep Trouble?

To be clear upfront, this is the part where we need to apply some common sense and speculate a bit.

There’s no research that not only reliably shows sleep trouble from calorie restriction, but also tries to explain why it happens.

From everything I’ve read, there are 4 likely reasons that a diet can cause insomnia symptoms.

Stress From Eating Less (or Differently)

Stress is the leading cause of insomnia, especially short term.

We’ve also known for a long time that many people eat food as a coping mechanism for stress (7). This includes people of all sizes, not just overweight people.

It seems reasonable to say that if someone relies on food to relieve stress in their life, restricting food can raise stress levels.

A study of 381 college students found that restrictive diets were linked to poor sleep quality and low mood (8). College students typically have relatively high levels of stress, so this sort of explanation makes logical sense to me.

The nefarious thing about stress and insomnia is that stress can lead to poor sleep, which often makes someone even more stressed. It’s a vicious cycle that can lead to chronic insomnia if it goes on too long.

Exercising Too Hard or Too Late

Recent research is showing that working out may cause insomnia depending on the intensity and timing.

  • Intensity - Moderate exercise seems to help sleep, while intense exercise is more likely to lead to sleep trouble. 
  • Timing - Exercising within an hour or two of bedtime is more likely to cause sleep trouble due to changes in hormone levels and body temperature.

Often, people start diets and also start exercising even though they’re not used to it. Going from no exercise to working out for an hour everyday is a shock to the body that may cause additional sleep problems.

The Type of Diet or Eating New Certain Foods

Certain types of diets are known to cause sleep issues.

For example, many people who start the ketogenic diet experience insomnia symptoms in the short term, and then sleep eventually gets better weeks or months down the line.

It may not be on purpose, but switching to a calorie restricted diet may significantly change the amount of fat, protein, or carbohydrates that someone eats compared to what they’re used to. Any big change in food can lead to changes in sleep.

A diet may also lead someone to eat more of certain foods that are linked to sleep issues. For example, chocolate is linked to insomnia, as are certain other foods.

Eating Schedule

A new diet can also come with a new eating schedule.

The main concern here is eating before bed, which can cause sleep trouble.

Large meals, particularly high in fat or fiber are the most likely to cause sleep issues, as they take a long time to digest. If someone has to eat before bed, a small portion of fruit is the best choice (9). There's some evidence that bananas can improve insomnia symptoms.

How to Improve Sleep While on a Calorie Deficit

The solution to someone’s sleep problems while on a calorie deficit will depend on the individual situation.

In general, the following things will reduce sleep troubles or correct them:

  • Reduce the deficit - Most studies where people did not have any sleep issues restricted calories by 300-500 (relative to usual) per day, and gradually increased this amount if needed.
  • Reduce stress - If food is a major coping mechanism for stress, finding an alternative is important. This may be exercise (running, yoga, etc.), meditation, massage, or even therapy.
  • Exercise earlier and lighter - If exercise is a potential cause of sleep issues, scaling back and doing it earlier in the day (ideally the morning) can help.
  • Improve sleep hygiene - Almost everyone can benefit by improving their sleep hygiene.
  • See a doctor - A doctor can check blood levels for any deficiencies (possible on lengthy diets), and also prescribe treatment like cognitive behavioral therapy if necessary.

Summary: Diets and Insomnia

Research suggests that calorie deficits to lose weight typically improve sleep quality in the long term. Most studies don’t note any significant short term adverse effects.

However, there’s some evidence that large calorie deficits, or deficits in people who are highly stressed can trigger symptoms of insomnia. In particular, taking longer to fall asleep was the most common result.

Minor sleep issues may resolve themselves over time, but severe insomnia symptoms should be evaluated as soon as possible by a doctor to try and prevent them from developing into chronic insomnia.

References

  1. Sleep and obesity
  2. Sleep in eating disorders
  3. Restricted energy intake affects nocturnal body temperature and sleep patterns
  4. Effect of Six-Month Diet Intervention on Sleep among Overweight and Obese Men with Chronic Insomnia Symptoms: A Randomized Controlled Trial
  5. Efficacy of fasting calorie restriction on quality of life among aging men
  6. Effect of Calorie Restriction on Mood, Quality of Life, Sleep, and Sexual Function in Healthy Nonobese Adults
  7. Women's eating problems
  8. An examination of the association between eating problems, negative mood, weight and sleeping quality in young women and men
  9. Effects of Diet on Sleep Quality

Medical Disclaimer: The information on SnoozeUniversity.com is not intended to be a substitute for physician or other qualified care. We simply aim to inform people struggling with sleep issues about the nature of their condition and/or prescribed treatment.


About the authorDale is the founder of Snooze University and a sleep researcher. I overcame my sleep issues and now I'd like to help you do the same by summarizing the latest sleep studies for you.