A response to the Rank the Research initiative
Researchers and providers continually explore how treatments for sleep apnea may impact an individual’s quality of life. One current debate regarding treatment is the influence of positive airway pressure (PAP) devices and other sleep apnea treatments on body weight. On the one hand, treatment for sleep apnea can improve one’s quality of sleep, which can then lead to improved alertness, energy and mood. Such improvements may then increase one’s ability to exercise and engage in other wellness activities that can reduce body weight. On the other hand, because treatment for sleep apnea may decrease the effort used for breathing during sleep, it is plausible that such treatments may reduce the amount of energy (and calories) burned during sleep (Quan, et al).1,2 If this is the case, and the reduction in nighttime energy expenditure is not balanced by an increase in physical activity and/or adjustments to one’s diet, there is the possibility that an individual may gain weight after initiating treatment for sleep apnea. In addition, changes in quality or patterns of sleep may occur with changes in appetite, eating habits, or even hormone levels, all of which could also potentially impact weight (Patel).1,3
Much of the research we currently have that examines the relationship between body weight and sleep apnea treatments has come from observing people over time or retrospective reviews of medical records, and not from what we call “controlled experiments”.4-6 In these “observational” or “uncontrolled” studies, it is difficult to determine what causes changes in weight even when such changes occur. For example, if a study looks at several individuals who use PAP, but does not include individuals who were PAP “free”, researchers cannot determine if changes in weight occur specifically because of PAP use. It might be the case that individuals receiving PAP treatment received weight management advice from their treatment provider and made changes to exercise or diet habits that caused the weight loss. To account or “control” for other possible explanations, researchers need to conduct studies where they can better isolate the effect of the treatment.
Recently, data from controlled experiments has been analyzed. In November 2014, the first meta-analysis (a study that analyzes data from a large number of other studies) was published (Drager, et al).7 The meta-analysis looked at data from 25 randomized control trials (RCT’s). An RCT is a type of study that randomly, by chance, assigns participants into an experimental group which receives one type of treatment or a control group which typically does not receive any treatment. As the study is conducted, differences between the control and experimental groups in the outcomes being studied (such as body weight) can be attributed to this random treatment assignment, and thus to the treatment being evaluated. These 25 studies all looked at the impact of Continuous PAP compared to non-PAP use, and the review of body weight changes from all of these studies together. The meta-analysis found that new PAP users experienced a slight increase in weight, estimated to be between 0.10 and 0.24 kg (0.22 – 0.53 lbs).7 However, the range of weight change following CPAP use varied by each study, from about a 1 kg (2.2 lb) decrease to about a 2 kg (4.5 lb) increase. Additionally, more than half of the studies available to the authors involved 50 participants or less, and more than half of the studies lasted 3 months or shorter. Also, because the meta-analysis reviewed overall data such as study averages, the authors were unable to assess whether changes to other influences on weight, such as physical activity or diet, affects the influence PAP has on the body weight of a particular individual. Thus, further research is needed to explore the relationship between sleep apnea treatment and body weight.
Possible directions for future research of this complex relationship include:
By conducting more research on how sleep apnea treatments influence body weight and one’s quality of life, researchers hope to provide the tools necessary for treatment providers to deliver the best possible care to their patients. You can get involved in this research by completing our surveys within the research portal of MyApnea.Org.
Until more research is available, it is prudent to recommend that all individuals (whether or not on PAP) follow healthy lifestyle recommendations, including following American Heart Association guidelines for nutrition and exercise. People who are overweight and starting PAP may want to identify this time as an opportunity to “start fresh”--with their renewed alertness, use this as the moment for a renewed commitment to eating right and being more active.
References
Kevin, thanks for this great, evidenced base summary. I know alot of patients may be disappointed that CPAP use itself does not usually lead to better weight control. How CPAP does effect energy balance is indeed a very interesting question. Your post also emphasizes that an "integrated" and balanced approach for health is a good tact- making sure that sleep, diet, exercise and stress are all addressed.
Interestingly enough, we figured out that there were issues with my apnea treatment because I gained 20 pounds. I had had success counting calories, and then all of a sudden I stopped losing weight, and then it creeped upward, until I had gained it back over the course of a year. After getting tested for a huge number of issues with my Primary Care doctor, he thought it might be related to my sleep apnea. I went for another sleep study (actually, several, but that's another story). It was then discovered that I had central apneas as well as obstructive. Now that we're treating that, I've been able to lose weight again, though we're still tweaking.
I started questioning my health not just because of tiredness and sleep issues, but also because of weight gain. I was in good shape, walked 2-3 miles per day, did Taebo, Zumba, and lifted weights. Then I began gaining weight for no apparent reason. At first I got the "menopause" excuse, then was told that often people eat more than they realize. I knew what I was eating and the exercise I was doing. Finally, when I pushed my Dr. about the tiredness and sleep issues she sent me for a sleep test and surprising even to me, it was positive for sleep apnea. Over the last few years as I've gotten more tired, my energy level has dropped, my weight has gone up, etc. I am eating the same or maybe even less. I am hoping that soon when I am treated, I will regain my energy and lose weight.
Kevin,
You raise an interesting question about weight gain. Of your bullet points of suggestions for future research, the third is most relevant to me as a person with OSA who has started using CPAP.
I have gained weight in my post menopausal years. I was once petite and thin and could eat anything without gaining weight. In recent years, I blossomed into a carbon copy of my mom (short and round, clinically obese) despite being active with swimming laps at the pool, going for bicycle rides on our local bike trail, walking a lot, etc.
In the 6 months prior to my OSA diagnosis (starting fall, 2014) I became very sedentary due to my extreme lack of energy. I was also probably eating more than necessary in an effort to "fuel my engine."
I have only been on CPAP for 6 weeks, but my energy and mental clarity are returning. I personally believe that with increased energy, and dedication, I will bump up my level of exercise, hopefully restrict my eating habits, and generally get into better physical shape. I only need to lose a few pounds to get myself out of the "obese" category and merely "overweight."
I would be interested to see the relationship between effective, nightly CPAP use, and long term effect on body weight.
Hi 2Sleepy:
Thank you for your thoughtful response to the post. I am happy to hear that you have been experiencing improvements in energy and mental clarity after starting CPAP. Using this energy to increase exercise sounds like a excellent goal. I know some individuals who, after increasing exercise, have experienced even greater improvements in energy, which can in turn make it easier to exercise, and so the cycle goes.
Thank you also for sharing which of the directions for future research would be most interesting to you. I agree that looking at body weight changes over time following the beginning of CPAP treatment is an important subject to evaluate. In the meta-analysis I previously mentioned (Drager, et al), there was only one study longer than 6 months whose data was available to the authors. In that 48-month long trial, both the individuals who used CPAP and the individuals who did not use CPAP actually lost weight on average, and the difference in weight loss was not significantly different from one group to the other. Thus, further evaluation is needed to understand how weight changes over time - a great area for future research!
In relation to weight loss .... I have been using a CPAP machine for 15 months now. I immediately started losing weight without effort or change once I started using the CPAP. Prior to that no amount of effort or willpower allowed me sustained weight loss. My opinion is that, for me, reduced cortisol levels as a direct result of using the CPAP machine and getting a good sleep, is the most significant factor involved, allowing insulin levels to drop lower and any urges to consume carbohydrates to subside. I have lost about 25kgs to date...still 50kgs to go. Other changes are that my mental acuity has increased with improved memory, organisational skills and decision making processes. My moods are more stable and I have much less moments of anxiety and depression. Physically, I do not exercise. I do little activity as I am disabled from neurogenic claudication, a condition I hope to improve through further weight loss and yoga. My diet is high fat, medium protein, very low carbohydrates. Plenty of water and few, if any, processed foods.
I personally feel that sleep apnea treatment as a primary cause for weight change is missing the big picture. Many, if not most folk I know on therapy with sleep apnea have complicating medical situations which are far more likely to cause weight changes than the therapy. Just my personal observation and of course, this comes from a non-professional. The physical characteristics of a person with sleep apnea may vary but many seem to be a bit overweight with thick necks. Sleeping soundly probably isn't going to be a cure-all for overweight as some of this may be facilitated by the drugs that person is taking for some other medical condition AND the person may have a family history of their ancestors being the same general shape as they are. I remember my grandparents and I am them (a bit on the chunky side) even after a LOT of exercise; both aerobic and anaerobic when I was younger. Also, the weight gain issue is fueled by a slower metabolism seen a lot in older folk like myself. I do think it is true that teenagers can eat like a tiger and seniors need FAR less caloric intake to sustain basal metabolism. Many seniors (at least one I am sure of) tend to want to eat like they did when they were 18 years old. It is a struggle and I doubt PAP therapy will make me perky enough to want to hit the weights and run again.
Hi wiredgeorge. There has actually been some data published that shows patients who are compliant with CPAP treatment experience weight gain. You might find this interesting: http://www.aasmnet.org/jcsm/ViewAbstract.aspx?pid=29161.
Has any study determined whether the weight gain that is seen in CPAP users is due to an increase in fat or an increase in muscle or both? One can imagine the possibility that muscle might increase as a result of feeling more energetic and exercising more.
There is a some data out there, but more research is needed. Here are a couple of interesting links: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3927445 and http://www.ncbi.nlm.nih.gov/pubmed/20118208. This small study showed that lean body mass increased in both males and females who were using CPAP treatment.
