Sleep and Losing Weight

Sleep can affect weight in two ways - gain and loss. Ill start with weight gain.
There can be many reasons behind a lack of sleep, ranging from working hours to stress. If you find yourself having a few hours of sleep each night, this can lead to weight gain. Someone that regularly has a lack of sleep, maybe only 4 hours a night, can very easily make poor nutritional choices. If they wake up after a short sleep, they will be tired, which means the last thing that will enter their mind is to go into the kitchen and mix up a healthy breakfast, they are more likely to get something fatty 'on the go'. This can actually progress throughout the day, which means they are avoiding the foods that they need to lose weight, and eating the foods they should be avoiding. If you are someone that suffers from a lot of stress, your most likely going to make poor nutritional choices in the first place, but if you add a lack of sleep into the mix, then you will most likely find yourself eating way more 'junk' than you should be eating, which is simply going to put weight on. It can feel like a vicious cycle, and the hardest part is to break that. So my advice is to find out the root cause of your lack of sleep and try your best to fix that. If you can fix it, then you won't be eating those bad foods as you will have a lot more energy and have a 'clear mind' to make correct nutritional choices.
Moving onto weight loss.
Its kind of the opposite effect of above. If you regularly get a good amount of sleep (7-9 hours per night) you are going to have a lot more energy, which will enable you to make good, healthy nutritional choices. You won't be looking around for a quick 'burst' of energy from a piece of cake, pastry items or sweets. As you will have more energy, you will be happy to go into the kitchen and make healthy meals, and not opt for a takeaway which requires little to no effort. Also, if your working out in the gym regularly, your body needs to recover, and nothing is better for that than sleep.
So, sleep can go two ways.... do the right thing and get a good nights sleep in!