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Does CPAP for Sleep Apnea Cause Weight Loss or Gain?

by Dale Cudmore | Updated: Feb 22, 2022

Being overweight is by far the most common cause of sleep apnea.

To make things worse, sleep apnea typically causes weight gain (along with other things like high blood pressure).

The big question is whether or not you can treat the symptoms of sleep apnea by using CPAP, and see an improvement in the underlying cause (weight).

I’m going to walk you through a summary of the research available on this topic. Overall it appears that CPAP doesn’t have much of an effect on weight. If anything, it leads to more weight gain in some cases.

Research on CPAP and Weight Loss

There’s been a decent number of studies looking at how CPAP affects BMI (Body Mass Index).

A 2008 study with 309 subjects compared BMI changes in those who use CPAP regularly with a control group who either used it sparingly or not at all (1).

After about a year (10-14 month follow-up), they found that the CPAP group had a small increase in BMI, while the control group had a small decrease.

One interesting note is that when data was filtered out to look at a “high-compliance” group of people who used CPAP nearly every night, the weight gain was even larger.

Another 6 month long study with about 1100 participants with obstructive sleep apnea found similar results (2):

Participants randomized to CPAP gained 0.35 ± 5.01 kg, whereas those on Sham CPAP lost 0.70 ± 4.03 kg (mean ± SD, p = 0.001).

Again, the patients using CPAP gained weight, while the “sham” CPAP (control group) lost a small amount.

There have been other studies that show neither a weight loss or gain while using CPAP, but these are typically shorter term (3).

SummaryCPAP alone doesn’t have a large effect on weight loss or gain. In the studies we looked at, the weight gain average from CPAP over the course of a year was around 1 pound.

How Could CPAP Lead to Weight Gain?

It seems strange that CPAP would lead to weight gain, even if it doesn’t lead to a loss.

The explanation for this still isn’t known.

One theory is based on energy expenditure during sleep. Research has shown that energy expenditure increases during apneic sleep, and declines when CPAP treatment is applied (4).

It’s not a huge amount of difference in energy expenditure, but over the course of a year or so like in the studies above, it could add up.

How is Apnea Treated if CPAP Cause Weight Loss?

Originally, there was a question of whether or not CPAP was an actual treatment for apnea that would improve the underlying condition of being overweight.

We’ve seen that CPAP is not effective for weight loss. So even if CPAP is effective for relieving symptoms while sleeping, it’s important to treat sleep apnea with a proper weight loss program.

This is not a website about weight loss, so I’m not going to go into any more detail at this point. But the bottom line is that someone with sleep apnea either needs to lose weight on their own, or get a referral to a dietician or other weight loss specialist if they need help.


  1. Does CPAP Lead to Change in BMI?
  2. Impact of Treatment with Continuous Positive Airway Pressure (CPAP) on Weight in Obstructive Sleep Apnea
  3. Effect of Positive Airway Pressure Therapy on Body Mass Index in Obese Patients With Obstructive Sleep Apnea Syndrome: A Prospective Study
  4. Energy expenditure in obstructive sleep apnea: effects of treatment with continuous positive airway pressure

Medical Disclaimer: The information on 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.