If you want to improve your singing voice water is an excellent source for voice therapy. The water has to come from the tap or be at room temperature, if it is too warm it could cause your throat to become scratchy and uncomfortable; You don't want to be up singing and clearing your throat at the same time.
Drinking ice cold or just cold water could tighten the vocal chords causing the voice to crack as if you were going through puberty, and you know how embarrassing that can be. Try not to drink a big tall glass of water if you don't plan on dancing too. Other exceptional liquids for voice therapy could be warm tea with honey no lemon and no sugar, this not only relaxes you but it also relaxes your vocal chords.
Milk, ice cream, or yogurt, is not good especially with food, it can cause mucus which is bad for those who have sinus problems like I do; unfortunately, sinus and singing doesn't mix well together.
Gargling mouthwash also helps, along with swallowing your own saliva. Gargling warm salt water can dry your throat, so don't do it. Clearing your throat can make things worse, so that wouldn't be good either just relax and swallow.
So, you're hungry and you know how difficult it is to sing on an empty stomach, well the first thing you can't do is eat a piece of candy. That is a big no no. Anything with sugar can make you thirsty and can cause excessive salivation, dry mouth, or burping. Saltine crackers are okay only if you drink water behind it.
If you plan on eating a big meal do it an hour or two before you sing in front of an audience because you never know what your body will want to do afterward. Chewing gum is only good before you sing and it has to be minty and sugarless. And Ladies we all know how good we love our chocolate but don't think you can eat it to relax because it will make your throat hot and your mouth dry, sorry.
Furthermore, Less fat in the diet is always a good improvement towards your health but it can also benefit those good old vocal chords. And as the saying goes, "you are what you eat", lets take care of those teeth because plaque can also play a role in maintaining an excellent voice. And remember, If you got it to flaunt you also have to take care of it or it will leave you.