In my last post, I posed the question “Why is my morning weight lower than my bedtime weight?” It’s true, you know. Your lowest weight is always in the morning.
Let’s see if I can explain it.
Basically, overnight weight loss is a combo of (1) water lost via the skin and respiration, (2) basal metabolic caloric expenditure and (3) urine loss in the morning. Water loss, excluding urine and feces, accounts for over 80% of the weight lost while sleeping.
Overnight weight loss may vary depending on how much time one spends in Slow Wave Sleep (SWS) vs REM sleep, with longer duration of SWS correlating with higher sleep weight loss. Slow wave sleep has been called the restorative phase of sleep, and increased exercise during the day leads to an increase in time spent in SWS during the night.
Energy expenditure during sleep varies with varies with circadian rhythms as well as sleep cycle. So one could hypothesize that disruption of these rhythms night lead to aberrations in weight.
The sleeping metabolic rate in non-obese individuals appears to be higher than that of their obese counterparts. Meaning that thin folks may stay that way, not just because of what they do while they are awake (namely, eat less and exercise more), but also because they burn more calories while they are sleeping. (I know. Totally unfair.)
Sleep deprivation has been found to be associated with obesity in adults, and appears to be a possible cause for the rise in childhood obesity. In this regard, I will tell you that I used to stay up till the wee hours blogging. But I don’t do that much anymore, and am definitely getting more sleep. I wonder how much that has contributed to my weight loss success?
While most of your overnight weight loss is water loss, don’t discount the loss that comes from the energy you burn while you are sleeping. It may not be a lot on a given night, but multiply it by 365 nights a year and it adds up.
The amount of energy you burn while sleeping seems to depend on how well and how long you sleep, so make sure you get enough shut-eye.
And while you’re awake, get some exercise. Exercise improves the quality of your sleep, and that may lead to more weight loss.
Now if you’ll excuse me, it’s way past my bedtime.