Lots of water with fresh squeezed lemon. Not eating is bad choice, you might lose a little weight but it will come back on as soon as you eat. Laxatives are addicting and you can throw off your electrolyte balance, loss of sodium, potassium and magnesium, along with other issues.
The only way is to use more energy than you eat. If you dont get enough energy, and dont eat enough, your might lose some weight initially, but it will come back quickly, and in the end you might end up actually gaining weight. This is because that the body can feel that it doesn't get enough energy to maintain itself, so therefore it goes into a kind of energy save mode. This means, that, in addition to becoming tired, demotivated and tons of other bad stuff, your body will start to try and save the fat, and instead you will lose muscle mass. (Let me repeat that, you don't lose fat, you lose muscles). Thus, when you start to eat normally, you will gain the weight you threw because the body is still relying on muscles, and thus not burning any carbs, you will be weaker, and you will end up with more fat that you started with. Have i made my point? So get your ass of the sofa, and do some exercising. Google how to calculate your metabolism, to find out how much energy your body needs to preserve itself, and know that you should never eat anything short of this. Good luck :)