text: can a lack of sleep actually prevent me from losing weight?   absolutley!  sleep performs a restorative function for the brain and body as evidenced by the myriad symptoms of metabolic dysfunction that result when animals are deprived of sleep.  therefore, by not getting enough sleep, you are not providing your body with the neccesary "refresh" stage that builds hormones and chemicals needed to keep your energy high enough to lose weight. lack of sleep puts your body into a different "mode" and you will have less energy, and feel less like eating right and excersizing. you might think you would be able to tell yourself you can fight that, but you cannot.  sleeping also is where your mind takes your short term memory and places into long term. so, lack of sleep makes you forget things more, and your body reverts to "insticts".   our instincts aren't that healthy for us sometimes... for example, your brain will ask for more junk food as it makes you feel "comfortable" and your brain will ask for more relaxing time, even without sleep.  trust me, you will not lose weight without proper rest, and lack of sleep will only help you gain weight, and stress your system!