Can CPAP Make You Gain Weight?

Scanning through my daily schedule of patients, I noticed Mr. Johnson was on the schedule. I have been following him for over 10 years since diagnosing and prescribing CPAP for his severe obstructive sleep apnea. I last saw him 3 years ago. He was faithful in using his CPAP 100% of the time, and his adherence numbers were perfect, with an average AHI of 1, minimal leaks, and being used 8-9 hours every night. As I entered the exam room and greeted him, I was shocked to see how much weight he had gained (30 pounds) over the past few years.

One of the basic tenets of sleep medicine is that poor sleep leads to weight gain. It naturally follows that sleeping better with CPAP will lead to weight loss. It’s not uncommon to see patients losing weight after sleeping better with CPAP, dental appliances or even after surgery. However, I had seen a few studies over the years showing that a small proportion of people using CPAP may gain some weight, but what I discovered over the past few weeks studying basal metabolic rates and weight loss in relation to CPAP was surprising.

It turns out that overall, CPAP use has been found to increase weight significantly, in proportion to how long you use CPAP. The more hours you use CPAP every night and the more number of years, the higher the amount of cumulative weight gain.

  • Researchers from Harvard and Stanford Universities found that patients randomized to receive CPAP for 6 months gained 0.77 pounds, whereas people on sham CPAP lost 1.5 pounds. Of note, people who more highly compliant (using more than 4 hours/night, at least 4/7 days/week) had higher degrees of weight gain.
  • In another study, overall BMI did not increase in CPAP compliant patients after one year, but women and non-obese subjects did gain significant weight.
  • A Finnish study in 2016 found that CPAP compliant, more obese patients had higher levels of weight gain after 5 years.
  • Lastly, a meta-analysis of randomized only studies analyzed over 3181 patients from 25 studies, finding significant weight increase in compliant CPAP users.

A number of explanations are given as to why CPAP can promote weight gain. The one most reasonable proposal that I saw is that when you have obstructive sleep apnea, your basal metabolic rate (BMR) in higher.  Due to the extra energy demands of having sleep apnea, you burn up more calories. It’s been shown that using CPAP reduces your BMR.  Since dietary intake and your body’s baseline weight thermostat does not change, you’ll end up with positive energy balance, leading to slow weight gain. This concept may also explain weight gain in some children who undergo tonsillectomy for sleep apnea.

Based on this finding, should people with sleep apnea stop using CPAP? Absolutely not. The overall risks of not treating sleep apnea (especially severe cases) far outweigh the potential risk of getting heavier. However, I do think that this potential side effect should to mentioned to all new CPAP users, just like any potential side effects for drugs or surgical procedures.

It’s also important to emphasize the importance of radically changing your dietary habits once you’re able to sleep better with CPAP. 

For those of you currently on CPAP, did you gain any weight? If so, about how many pounds?

Please note: I reserve the right to delete comments that are offensive or off-topic.

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28 thoughts on “Can CPAP Make You Gain Weight?

  1. Great article. This proposes a very interesting explanation for weight gain in CPAP users. I didn’t realize that having sleep apnea can increase BMR for these individuals. By how much does BMR increase? Absolutely agree that lifestyle counseling on proper diet is one of the best things healthcare providers can do for this patient population.

  2. I’m pretty new to the Cpap and really surprised at the change in my energy level in the last month of wearing it, The last 4 years I have done a low carb with some fasting weekly I did notice it was harder to comply with the fast with the the lack of sleep so for me i guess even if my BMR goes down i will be able to fast more consistantly.

  3. Thank you!! I’m not crazy.
    Have been doing WW for three years now and am discouraged to see that I’ve regained half the weight lost. Doctor thinks I’m crazy and has referred me to a dietician, who is also stumped. Weight loss chart is absolutely stable until it trends up dramatically when I started CPAP. Have now gained 13 lbs since July and am stressed beyond belief. Can you help?

  4. I have been using bipap for 3 years. My weight was always stable but since starting bipap I have gained 45 pounds. Still walk 4 miles every morning, cut my potions and nothing helps. My sleep apnea is under control but seriously considering just using it less hours a night or every other night.

  5. I’m a normal weight woman who’s struggled with mild overweight in the past and who practices extreme self-discipline to maintain my weight now. I used my CPAP for almost three months and from the beginning, I started gaining about 2 pounds per month. When I was up about 5 pounds, it dawned on my that it coincided with when I started the CPAP. I haven’t used it now for the past three nights and I don’t think I’ll go back to it.

    P.S., I think you meant to say “tenets” and not “tenants” above, since you’re not talking about rental property.

  6. Were these “studies” funded by the American Dental Association so they can sell more Oral Appliances over CPAP? The purported weight gain from CPAP use is absurd considering the small sample sizes for these studies. Even your anecdotal story of your patient who used his CPAP for 10 years makes zero logical sense. How come with diligent CPAP use, he didn’t gain any weight in the first 7 years? It all sounds like an urban legend to me.

  7. Morning, I was diagnosed many years before I got to the point of being given a CPAP machine. I was basically unmonitored for 10 years but it wasn’t until I told my gp I was dropping off to sleep at the drop of a hat all day that I got referred for a machine. I had my machine at the end of August 2019. My AHI is now less than 2 and so I am pleased with that but I am continually gaining weight and it is making me so depressed. I have gained around 40 pound and don’t know which way to turn as the GP is no help.

  8. Weight gain after using CPAP is a well-documented phenomenon in a minority of patients. There are even studies showing weight gain after tonsillectomy in children. When you alter the relative energy balance (whether by CPAP or surgery), some people seem to be prone to weight gain.

  9. I am a 60-year-old woman. I have been slightly overweight for years. I have been using a CPAP machine for a year and a half now and have gained over 30 pounds. this is not an “urban legend”, this is true weight gain! I have not changed my dietary habits. If anything, I have reduced my caloric intake. If anyone has any suggestions for weight loss when using a CPAP please let me know.

  10. I’m new to using CPap & yes I’ve gained lots of weight. (Last 6mo) I’ve never had weight issues but only since starting CPap My waist is getting larger. It’s not “urban legend “. I’m sure it has to do with your metabolism. Previously I was proud of myself for always maintaining my weight my entire life. I exercise daily & eat right. My plan is to become more adamant with more exercise and less calorie intake.
    I also plan to use the CPAP Less hours to see if it helps.

  11. I have been on cpap for 2 months now. I have made no significant dietary changes or changes to my activity level, but I have been steadily gaining weight. It didn’t occur to me that it could be from cpap use. I actually did an internet search to see if cpap can cause bloating, because I have felt that way lately too. So am I understanding this correctly, that if I cut my caloric intake, that cpap weight gain will no longer be an issue?

  12. I see lots of comments about weight gain after CPAP but no solution. I too am in this category.
    How do we lose weight now?
    I have put on 20 pounds in 1.5 years. There is a definite connection.
    I was the same weight for years. I have the graph on my FitBit. Once I started CPAP it spiked right away. 8 pounds that first month. And I haven’t been able to lose it. Super upset as I thought the scale was going to go in the opposite direction once implementing CPAP. There is a 100% connection here.
    Any advice would be appreciated.
    I want to keep using the CPAP but also want to stop the incline on the weight graph.

  13. I’m happy to be reading this as I thought I was crazy. I started cpap therapy oct 2020 and now March 2021 I can’t believe the change in my abdomin-puffy. I’ve been on a LF vegan diet – no salt oil sugar – very minimal nuts seed for 2 years and weighed 135lbs. Now I’ve gain 6 pounds and the only change is cpap. Very disheartening and while I notice improvement in alertness. I’m struggling with the machine as I find the headgear and tubes impossible. Any advise today correct this would
    Be most helpful.

  14. I’ve also dealt with very unwelcome weight gain of 30 pounds (about 5 per month) after starting CPAP (then bilevel, and now ASV), and I’m very compliant. Sadly, there is a positive correlation between level of compliance and weight gain.

    I’ve reduced carbs, increased exercise, and added daily intermittent fasting and HIIT workouts, and I’ve been able to at least stop the gain and lose a few pounds, but it is an Herculean task that really gets in the way of everything.

    Even with all this work, my blood tests hae been very disappointing; my blood sugar and HA1C are up, my usually excellent cholesterol ratio is moving in the wrong direction, and I’m just watching in a kind of slo-mo horror.

    I haven’t found a doctor who is curious enough or educated enough to explain or even explore the mechanism behind this, but I did find this man who suggests that the machines may be breathing too often, too fast, and with too much volume. I don’t understand this mechanism, and as far as I can decipher, neither does he. But he does report that after manipulating his machine, he has lost the weight.

    My problem: My pulmonologist is in charge of my machine’s settings, and he’s in the “You must be eating too much” camp.

    It may help you to read through this:

  15. Yes! I have been using my machine for three months now for 7 to 8 hours every night. I have gained 6 to 7 pounds since January😞

  16. After seventeen months on CPAP I gained 25lbs. I started using CPAP in Nov 2019. I immediately noticed better sleep, less day time drowsiness and no more morning headaches and lower blood pressure to the point I was removed from blood pressure medication. When I first started CPAP I was traveling a lot and did not take my CPAP so looking back at logs I averaged CPAP use a few nights a week over a month average. However, once I started traveling with my CPAP I noticed the weight gain came quick. Now that I use my CPAP every night I’m back to where I started without CPAP. Daytime sleepiness, morning headaches, high blood pressure with the added quick weight gain. After reading this article I wonder if I should limit my CPAP use to a few nights a week.

  17. I do wonder, with this weight gain, if CPAP is doing something unhealthy to us beyond just packing on the pounds.

    My usually excellent blood test results have gone in the wrong direction since I started CPAP, and so at least in my case, the weight gain is not the only negative side effect. I’ve had a rise in blood sugar, a rise in the wrong kind of cholesterol, and signs of non-alcoholic fatty liver disease — what in the heck?

    I’ve been completely off my CPAP for a few weeks and have lost weight. I’d really like to talk to a doctor or researcher who knows what’s happening here.

  18. Yes I have gained 30 pounds since I started I don’t know what to do very depressing WHT can I do about it?

  19. Ms. Brown, and all the others that are struggling with weight gain while on CPAP, one option is to find an alternative treatment for your sleep apnea. Unfortunately, all the studies documenting this phenomenon were unable to provide any practical, useful solutions. Hopefully, further research will be able to show why this occurs in some people, whereas in others, people lose weight once sleeping better on CPAP.

  20. I’ve heard that cpap machines produce plastic toxic fumes from the steam passing through plastic tubing during cpap operations but I haven’t seen anyone test for that all I’ve been able to find is this what if patients are inhaling plastic fumes that contributes to weight gain even while using cpap normally?

    Is it true that water reservoir harbors Covid 19 and other bacteria if not cleaned properly? The tubing is mostly not going to be cleaned in general by cpap users and could potentially contribute to weight gain also.

    If so and it’s extremely hazardous that would explain the uptick in semi tractor trailer accidents since cpap is becoming more commonly, “prescribed” to patients and also rumored sleep studies are registering false positive tests. Maybe check the equipment at facilities that have a high output of sleep apnea diagnosis such as mainly trucking companies.

    I think the patient should decide if they want to risk using a cpap machine rather than physicians since not only could cpap machines be harmful but could be mis diagnosed for a profit motive by physicians rather than based on health benefits.

  21. I have been on CPAP therapy for 3 years and I have now gained 55 pounds. I was already considered to “obese” because of my weight 270lbs at 5’10”. I’m built like a brick shit house or I was! Now I’m more like a walking jelly roll.

  22. I’ve been using a cpap going on 1yr 5 months and have gained 15 lbs. I noticed after a couple of months I had gained weight. I exercise 5 days a week started eating differently and found nothing works. I wasn’t eating that bad to begin with. At first I didn’t know what was going on and then it hit me, the only thing different, I was using a cpap. I talked to my lung doctor and her response was calories in calories out. REALLY! She also said that I wasn’t burning as many calories as I was before the cpap. I wish I had a solution. Since all of this my bad cholesterol is 300 and good 59, now I take meds. Not happy.

  23. Hi — just an update. I did get my Basal Metabolic Rate tested at the doctor’s office, and it’s quite a bit higher than they thought it would be, based on my weight gain. However, I work out regularly and I’m very muscular, so your mileage on that test may vary.

    In my case, the BMR hypothesis was wrong.

    After some shocking blood test results that had all of my values moving in the wrong direction, I went off CPAP in April as an experiment (my pulmonologist agreed), and I’ve finally been able to lose the weight. 17 pounds in 2 months, so far.

    My apnea isn’t bad, so I’m not endangered. I’ve also added mouth taping at night (see the book Breath by James Nestor) to make sure that I’m not snoring.

    I’m going for a sleep study next week to see how my apneas are. I have to say that I don’t miss CPAP at all.

    I’ll also be redoing my blood tests next month for a regular visit, so I’ll know if that sudden bad movement in all of my blood values has alleviated.

    I’m really thinking that something unhealthy happened to me — that something in CPAP treatment needs to be looked at very seriously if it’s having this wildly negative effect on so many of us.

    One problem: weight gain is looked at as a character flaw, so I don’t know if that prejudice will continue to get in the way of responsible research. Also, the old calories in/calories out message is extremely simple-minded, and it doesn’t take metabolism into account at all. My body doesn’t do simple arithmetic with calories — it does calculus!

    I’ll report again after my sleep study and blood tests.

  24. I have used a CPAP for about 2 months and I’ve already gained about 10 pounds. This makes me feel bloated and uncomfortable all day and I don’t like it. I’m going to find other ways to help my sleep apnea because the weight gain is too significant and uncomfortable.

  25. Have gained about 80 lbs. over past 20 years of CPAP use. About 25 of those pounds were gained during past 10 years. Use CPAP machine every night and during the day if fatigued. Right now usage (hrs.) shows 9.56. Using new Resmed for a month; April-May, 2021. Automatic pressure settings determined increase from 11 to 14. Having difficulty adjusting. Have not been able to walk any distance or stand longer than 10 minutes for a few years and it’s getting worse! Gained 7 lbs. during pandemic (2021). Don’t eat that much but weight keeps going up. Have Lupus (diagnosed Sept., 2019) but advised it is in my DNA; Type II diabetes (diagnosed about 1998) and BS went over 800 while in the hospital in 2018; Take vitamins every day (vitamin D3-5000, Omega 3-600mg, multivitamin, vitamin C most days) but have taken extra vitamin since age 19. Have been a smoker for many years. Husband quit smoking 19 years ago and after 10 years developed
    breast cancer now metastasized to bone cancer. My mother had quit for over 30 years and died with leukemia at age 61. Smoking not the cause. Any help for me? Very difficult to walk, exercise, stand, and continually gaining weight. Will be 73 in August.