Sleep and weight gain are closely linked and we’ve known about this link for a long time. Obesity and sleep apnea often occur together, as does depression and obesity and other mental health disorders and obesity. Anything that causes lack of sleep could indirectly be linked to weight gain, and although we’re not yet sure exactly why lack of sleep could lead to weight gain or whether sleep apnea itself causes hormonal changes that lead to weight gain, there are a number of different factors associated with lack of sleep that could lead to an individual being unable to lose weight or to gain weight.
Lack of sleep can cause many problems – irritability, mood changes, feeling unable to cope with daily life and being unable to enjoy social activities in the same way that you used to. Because of this, you may turn to food for comfort because of the way you’re feeling, and you may also turn to food to wake you up, such as energy drinks and sugary coffee, both of which are full of calories. If you feel tired mid-afternoon, you might reach for snacks such as a chocolate bar to pick you up a bit and the consumption of these extra calories could lead to you gaining weight.
We also know that sleep deprivation lowers levels of a certain protein that controls and regulates your appetite, called leptin. These low levels of leptin could lead to an increased appetite or an inability to feel completely full, so you eat more food than you used to, leading to weight gain. Another reason for possible weight gain is because lack of sleep leads to low energy levels, meaning that you are less likely to exercise as much as you used to and also that you are more likely to choose foods of convenience, such as microwave meals or other processed meals rather than choose healthy foods and cook meals from scratch.
Recent research has also shown that there is a correlation between sleep apnea and obesity. Although we don’t know what this link is or why it occurs, we do know that obesity and sleep apnea aggravate each other. Sleep apnea can lead to weight gain, but weight gain can cause sleep apnea, so it can be a vicious circle. One study showed that those with an AHI of over 15 gained on average an increase of 0.52kg/m2 of their BMI, whereas those with an AHI of between 5 and 15 gained on average an increase of 0.22kg/m2 of their BMI. The study showed that those with severe sleep apnea were more likely to experience weight gain, but those with mild to moderate sleep apnea were still likely to gain some weight.
Another study done in Japan showed that men who slept for less than five hours per night were twice as likely to experience weight gain than men who slept for between seven and eight hours per night. Men who slept excessively for over nine hours per night were 1.4 times more likely to gain weight than those who slept for between seven and eight hours per night.
So we do know that sleep apnea and lack of sleep are related to weight gain and obesity, but that doesn’t mean that you will definitely gain weight when you have a sleep disorder. You can work closely with your doctor to develop a diet and eating plan that will allow you to not gain weight – but you need to remember that if you do have sleep apnea, you need to make far more of an effort to keep your weight stable and steady than you might have had to in the past. Eating habits and exercise that you might have followed in the past may have been successful before, but they may not work for you now, so you need to develop an eating plan that works for you today.