The link between sleep apnea and weight is a complicated one. Past studies suggest that those with untreated sleep apnea consume more carbohydrates and fat than those without untreated apneas, presumably because they are sleepier and crave foods that will give them a boost of energy. Additionally, anecdotally, many report losing weight once they start their continuous positive airway pressure (CPAP) treatment, but some also report gaining weight. Based on this conflicting data, a recent study set out to see whether dietary changes were present when those with untreated sleep apnea were prescribed to CPAP treatment.
Using a large subject pool of 231 subjects, a research team examined the diet of untreated sleep apnea subjects using a broad range of questionnaires. These questionnaires asked questions regarding calorie consumption, amount of daily recreational activity, food choices, portion sizes, etc. Half of these subjects were then assigned to CPAP treatment, and the other half was assigned to a “sham” CPAP. This sham is basically a fake machine that looks and sounds like a real machine. Subjects using sham CPAP are under the impression that their machine is actually working and that they are being treated. This machine is necessary to control for placebo effects that may be present when people know they are participating in a study. Dietary questionnaires were repeated after 4 months on CPAP or sham, and results were compared with before-treatment scores.
A number of interesting results, some expected and some unexpected, were found. Not surprisingly, in the CPAP group, fat intake was related to quality of sleep, meaning those with poorer sleep quality had a larger fat intake. In the sham group, men decreased their energy expenditure levels compared with the treated CPAP group. Similarly, women in the CPAP group increased their energy expenditure compared with the sham non-treated group. Interestingly, though, there was no decrease in total calories, protein, carbohydrates, or fat in the treated group after 4 months of treatment, which is the opposite of what was expected1.
Although dietary changes were not evident in this study, it is of note that energy expenditure was greater in those who were treated than those who were not treated. This may suggest that weight change after initiation of PAP devices may not be from a change in diet but actually from a change in physical activity. This makes sense, considering treating sleep apnea usually results in a decrease in sleepiness. With less sleepiness, one may be apt to get out and do more, ultimately leading to a decrease in weight.
Pre-publication, Journal of Clinical Sleep Medicine: Impact of CPAP on Activity Patterns and Diet in Patients with Obstructive Sleep Apnea (OSA)