Do you sleep for a reasonable amount of time but still wake up exhausted the next morning? Are you infamous for your earth-shaking snores? Unrestful sleep and snoring aren’t necessarily signs of sleep apnea, but they are the primary symptoms, and it’s a pretty common condition that can seriously affect your health – and your weight.
What Is Sleep Apnea?
People with sleep apnea might feel like they’re sleeping through the night, but actually their body briefly stops breathing (or breathes very shallowly) at several points during the night. Most commonly, this is because their airway physically closes (this type is called Obstructive Sleep Apnea). The airway can close for any one of many reasons: sometimes it’s just built a little funny, and sometimes the person’s sleeping position or another feature of their body puts extra pressure on it – obesity is a major culprit here.
In any case, when the airway closes and breathing temporarily stops, the body wakes up just for a second, so the person can consciously breathe again and fall back to sleep. Waking up this way is so short that most people don’t remember it in the morning, but it’s enough to throw a normal sleep cycle completely out of sync, making the night much less restful.
Sleep apnea is much more common in people with obesity (20-40%, compared to 2-4% in the general population), but thin people can also have it. In this study, researchers looked at patients with symptoms of sleep apnea (e.g. snoring, daytime fatigue, etc.). 77% of the normal-weight patients, 85% of the overweight patients, and 91% of the obese patients had apnea. In normal-weight patients, apnea was more likely to be milder.
If sleep apnea just made you tired and grumpy, it would be bad enough, but it’s actually more serious: like anything else that keeps you chronically sleep deprived, it might be a risk factor for cardiovascular diseases, stroke, high blood pressure, and other chronic conditions. It’s inflammatory. It also affects metabolism and metabolic disorders: in this study, for example, the worse the subjects’ sleep apnea was, the worse their glucose tolerance was. This review goes through all the evidence on sleep apnea and metabolic syndrome. Sleep apnea is also associated with more visceral fat (fat around the organs), which is much more dangerous than subcutaneous fat (fat just under the skin).
Typical therapies for sleep apnea include appliances that can physically keep the airway open or a CPAP (Continuous Positive Airway Pressure) device, which pushes air continually through the airway, preventing it from closing. Those interventions are often necessary and good, and it’s great that people have access to them. But there are also diet and lifestyle changes that can help in addition to the machines.
Diet and Sleep Apnea
When it comes to diet, weight loss is usually considered a first-line treatment for sleep apnea – and indeed, weight loss does work. Whether it’s diet, exercise, or diet + exercise, losing weight significantly decreases apnea symptoms. But considering that sleep is so important for weight loss, this can sometimes be a vicious cycle: you could improve your sleep by losing weight, but to lose weight, you have to sleep first!
That very effect is documented in this study: 77 men entered a 1-year lifestyle intervention study. All the men got the same intervention, but men with sleep apnea lost less weight and saw fewer metabolic improvements in response. The worse their apnea was, the less they benefitted from the intervention.
This suggests that simply recommending “weight loss” isn’t enough, since the weight loss is hardest precisely for the people who need it most. If your sleep apnea is preventing the weight loss that would get rid of the sleep apnea, you’re not going to get very far.
One solution is very simple: use a CPAP or another physical therapy as a kick-start to help make the lifestyle changes. Studies that combined diet + CPAP showed better results than studies with diet alone, although not all the trials agree.
Unfortunately, there's barely been any research studying whether any one particular type of diet works better than another. But there are a few clues:
The Mediterranean Diet
This study found that a Mediterranean diet improved REM sleep more than a “prudent diet” (read: low-fat, whole grains, etc. etc.) Subjects on the Mediterranean diet ate three times more fruits, vegetables, legumes, and fish than the “prudent diet” subjects (incidentally, they also lost more weight and got more exercise, as well as showing better adherence to the study diet).
That’s a point for the olive-oil-and-seafood crowd - and in many diet studies, "Mediterranean diet" ends up being something close to Paleo. The problem with this study, though, is that it’s hard to figure out what caused what. Was it the greater weight loss that improved symptoms, or was it something about the diet itself? Also, the authors noted that the Mediterranean diet didn’t improve overall symptoms, and that the significance of the REM sleep improvement is unclear.
Sleep Apnea and Carbs
Also on the diet front, an interesting clue is the connection between sleep apnea and metabolic syndrome. Sleep apnea and Type 2 Diabetes are very closely connected, not surprising considering the effects of apnea on glucose metabolism!
The metabolic damage that frequently comes along with apnea might be one of the reasons why people with sleep apnea find it so hard to lose weight. And this suggests that a lower-carb diet might be useful, at least as an initial therapy.
There haven’t been any studies testing a low-carb diet for sleep apnea. But here’s some testimony from Dr. Mary Eades that low-carb diets are effective for apnea in a clinical setting. Considering that a lower-carb diet is a fairly cheap and safe intervention, it’s at least worth a try!
Exercise and Sleep Apnea
With the metabolic component of sleep apnea, you might expect to find that exercise also helps, but here the waters are muddy. Exercise does seem to improve sleep quality in general, but its effect on apnea specifically is unclear and likely to be small.
This study, for example, found that an “individualized exercise training” program improved both metabolic health and sleep apnea symptoms, together with a loss of body fat. The exercise programs included 45 minutes of cardio, 30 minutes of strength training, and some stretching and balance exercises 6 days a week.
This was in conjunction with diet advice, though, so it’s not totally clear from the study that the exercise per se caused the improvement. And did the benefits come from the exercise or the weight loss it caused?
A few other studies (like this one) have found that exercise itself improves subjective perception of sleep quality (i.e. subjects feel like they “slept better” and feel less sleepy during the day) even though it doesn’t improve objective measurements of apnea. Maybe not perfect, but definitely better than nothing!
The bottom line: exercise is never a bad idea, but it probably won’t heal sleep apnea on its own.
Summing it Up
Sleep apnea is easy to brush off as “just snoring,” but in fact it’s a potentially life-threatening problem. Obesity can make it worse, but normal-weight people can also have it: just being at a healthy weight doesn’t make you immune!
It’s well established that weight loss helps with sleep apnea, but since apnea makes weight loss so much harder in the first place, it’s worth looking into the specifics of diet to see what might help. Since sleep apnea is so closely related to diabetes and metabolic syndrome, one promising option is a lower-carb, anti-inflammatory diet: think fish, olive oil, fruits and vegetables, and moderate exercise (to help with the symptoms, if nothing else).
And there’s absolutely nothing wrong with combining diet and a CPAP machine or a physical appliance: as with any serious medical problem, your doctor will be able to give you the best advice about what’s likely to work for you personally.