As bizarre as it sounds, how well we sleep can have a direct impact on the amount of weight we gain. While doctors often talk about how poor sleep impacts immune function and stress hormones, we’re only more recently beginning to understand how hormones that control appetite are also affected.
Leptin and ghrelin are hormones in our system that regulate feelings of hunger and fullness. Ghrelin, which is produced in the gastrointestinal tract, stimulates appetite, while leptin, produced in fat cells, sends a signal to the brain when you are full. Lack of sleep leads to both a lowering of leptin levels (lack of satiety) and a rise in ghrelin (stimulated appetite). The combined effects of these changes leads to overeating, followed by weight gain.
One example of this effect was demonstrated in a joint study between Stanford and the University of Wisconsin. Those who slept less than eight hours a night not only had lower levels of leptin and higher levels of ghrelin, but they also had a higher level of body fat. Those who slept the fewest hours per night weighed the most.
While this information is certainly promising, the relationship between these hormones and weight gain is still not entirely straightforward. Some patients who have sleep apnea, combined with obesity, actually have high levels of leptin, rather than low. It’s been speculated that some patients may become resistant to this hormone, so elevated levels mean their body isn’t responding to the signals of this hormone, still making them more prone to weight gain as a result of sleep apnea.
I think the bottom line is that diet and exercise aren’t the only factors when it comes to addressing weight gain. Poor sleep or untreated sleep apnea should always be addressed with any weight loss program, if any level of success is to be achieved.
