Just like your car needs gas and oil, your body needs food and water to run. Being hungry or thirsty can affect more than just your workout, it can affect your health. When you are dehydrated your heart has to work harder, and working out on an empty stomach can make you sluggish and affect your reaction time. 

Water is the best hydrator for the casual athlete, despite all the commercials on TV which would have us believing differently.  While everyone’s needs are different, a general rule of thumb is to drink enough water throughout the day and through your workout to maintain light-colored urine. If you’re drinking too little water your urine may appear dark yellow; your first indication that you need to drink up. Another reason it’s important to drink throughout the day and not just during your workout is because when you are working out your thirst response may be dampened or delayed which can result in taking in too little water without realizing it.

If water is like the oil your body needs, gas is like to fuel. Many people wrongly assume that if they exercise on an empty stomach they will burn more fat. This is simply not true, exercising on an empty stomach can actually sabotage your weight loss efforts because you cannot work out as intensely without the proper fuel and because you can get so hungry that you over does it at the drive through after your workout. The best bet is to be sure you eat enough to fuel your workout so you’re not starving, and you have the energy you need to walk that extra mile, or lift those extra five pounds.