Quote:
Originally Posted by shapedself
No, weight loss comes from the calorie deficit. It may make you more vulnerable psychologically to going off the diet, but so long as you stay on it you'll lose weight.
Yes, but it can be harder to create the calorie deficit - there's quite a good deal of evidence that sleep deprivation actually can reduce your metabolism - so even though you may be eating less than your "normal" you also may be "burniing less." As a result, sleep deprivation actually can make it more difficult to acheive a calorie deficit.
Just as an example (the numbers are entirely fictional). Say you normally need to eat 1800 calories to maintain your weight when you're getting adequate sleep, but when you're sleep deprived you're only burning 1550. If you don't reduce your calorie level, you're going to start gaining 1/2 pound per week. Also, if you were to reduce your calories to 1550 you would be eating less than "normal" but you wouldn't be losing any weight because of the metabolic slowing caused by the sleep deprivation.
When people talk about creating a calorie deficit, they sometimes forget that the "calories out" (the calories burned) is not a constant (not only is it variable, we don't know all of the variables and even the ones we do know about, often aren't under our conscious control). If you reduce your calorie intake, but your calorie expenditure also is reduced, you're not going to lose as much (or may not lose at all).
That's why many people find that they actually lose more weight when they increase their calorie intake. This sounds counterintuitive until you realize that the calories out part of the equation is variable and can be effected not only by calorie intake, but by other variables as well. Just as an example, if you cut your calories too low, you may be more easily exhausted and less likely to exercise. The same is true of sleep deprivation. If you're not sleeping well, it's going to be much more difficult to exercise and be active. Your body may even "spend" less energy on running your immune system (this is one of the theories behind the connection between sleep deprivation and weight gain, as it's known that sleep deprivation not only is associated with weight gain, it's also associated with a weakened immune system).
There are a tremendous number of factors that can affect our metabolic rate, not to mention the "voluntary" parts of the calorie burning (like intentional exercise) and the involuntary or subconscious ones (for example people who are sleep deprived have been shown to become more reserved in their normal body movements - they fidget less, for example, they sit stiller...) There are so many subtle changes, that we're not even able to be consciously aware of.
Even more important than the potential adverse effects on weight loss, are the other serious health risks associated with sleep deprivation.
Even though studied many of these in college (as an undergraduate and in graduate school), I didn't really "get it" until I experienced it myself. When my doctors told me that I would lose weight without trying and without changing my eating habits, I didn't believe it - because I falsely assumed my metabolism (the calories out) wouldn't change.
Within 6-8 months, I had lost 20 lbs without dieting and without changeing my eating habits or exercise habits at all. I might not have been all that surprised at 5 lbs, but 20? Just from better sleep? When I asked if my experience was typical, I was told that it absolutely was. I never in a million years would have expected such a dramatic difference, and so quickly. Often while dieting I didn't experience a 20 lb loss in 6 months of actively trying and yet doing nothing (except sleeping better) was able to accomplish what I couldn't with intentional effort.