The minimum daily recommended water intake is 2 liters, because this is how much water the body uses throughout the day through sweating, urination and other bodily functions. Without replenishing lost water, the body goes into dehydration and all functions start to suffer, which is why dieting professionals recommend abstaining from food, but never from water.
Like many other bodily functions, the metabolism is dependent on water to work properly.
Without enough water, the process of breaking food down and converting it to energy slows down dramatically, which means that too few calories are burnt and that too little weight is lost.
Not drinking enough water can be compared to "running of fumes" and if you're dieting and you seem to have hit the plateau, then you are probably not drinking enough water. When the metabolism slows down, weight loss slows down even more dramatically, especially since exercising becomes less effective as the body's energy levels diminish.
Water also plays an important part in the process of digestion and elimination of residues. Not drinking enough water is a one-way ticket to constipation and a host of other problems of the intestines.
Poor digestion means that you will not get enough energy from the food you're eating. This will prompt the body to ask for more food and this is how the weight loss process stops and the weight gain process begins. A dehydrated body sends out fake hunger pangs, thus tempting you to forget about the diet and eat more food than you should.
Not to mention that water is also a good filler. If you want to eat less food, drink a tall glass of water half an hour before every meal. The water will fill a large part of your stomach and the body will be content to feel that the stomach is not empty. This is not idle speculation, but a sound advice whose effectiveness can be confirmed by many dietitians and weight loss experts. Nobody can overeat with half of the stomach filled with water and with the body telling him/her: "Seems like we're almost full. We don't need that much food, so cut it short this evening".
Keep in mind that in order to reap the benefits of drinking enough water, you will want to spread the intake throughout the day.
Don't drink 2 liters of water all at once because the body will simply flush the excess and a lot of it will simply be wasted. Also, you don't need to restrict yourself to water.
Fruit juices, weak tea and coffee count as liquids that can be used by the body for hydration.
Alcohol is out of the question, because alcohol has the opposite effect on the body. And, ladies, don't be afraid that drinking a lot of water will make you retain it.
It's dehydration, not abundance, which forces the body to hang on to what it has.