Running in the Morning Without Eating or Drinking

Trail running

Running is an exercise that can be stressful to your body. To ward off some of the stress and strain of running, you must be adequately hydrated. Hydration helps to regulate your body functions as you run. Fuel, in the form of food, is also important prior to running. However, if you find yourself without time to fuel up before your morning run, you can make up for it afterward.


It is not a wise decision to run in the morning without taking in some fluids. "The Competitive Runner's Handbook" recommends following the American College of Sports Medicine's hydration guidelines. About two hours before you intend to run, drink two 8 oz. cups of fluid. Wait an hour. If you haven't urinated, drink another cup. Between five and 15 minutes of your start time, consume another one or two cups of fluid. Once you start running, your kidney function will decrease and the fluids will remain in your body. The fluids will help you maintain a lower heart rate and body temperature while running, in turn putting less strain on your body.

Over Hydration

While you should hydrate before running in the morning, be careful not to over-hydrate. According to a 2007 "Running Times" article, runners who consume too much water or other fluids -- forcing themselves to drink even when they are not thirsty -- may actually be reducing their ability to conserve fluids while running. This happens because your body is in a state of constant hydration. A compound in the kidneys that helps them respond to dehydration by conserving fluids diminishes after long periods of hydration. Thus, your kidneys can fail to retain fluids while you run, leading to severe dehydration and other health issues. As with so many other things, moderation is the key to hydration.


Whenever possible, you should eat before running in the morning. Food will boost the energy levels in your muscles, which will give you sufficient power to get through your run. Eating also gives your body and brain the nutrients they require to perform at optimal levels. If you eat before running, you will likely have a higher level of endurance and feel better about your workout.

Eating Strategies

If you are an early riser who has time to eat breakfast and let it digest before running, you should do so. Eat low-fat foods that are high in carbohydrates and contain a moderate amount of protein and aim for consuming between 400 and 800 calories. Toast, fruit, cereal and bagels are good options. If you sleep until it's time to roll out of bed and hit the pavement, you won't have time to digest a full meal before running. This could lead to nausea or cramping before you run. Try a carbohydrate drink or energy gel as you run out the door. If you can stomach it, something light, such as half a bagel is a good option. A high-carb meal the night before can also help fuel you. To avoid fatigue, eat a post-run meal that contains both carbs and protein within an hour of running.

Running on Empty

Dehydration can occur if you fail to ingest enough fluids. A 1990 study published in "Medicine & Science in Sports & Exercise" found that running without proper hydration can lead to gastrointestinal distress. Failure to hydrate also increases strain on your heart and can raise your body temperature to dangerous levels. Running without eating, on the other hand, can eat away at your endurance and leave you fatigued. People who don't eat prior to exercise in the morning, or who fast for 12 hours prior to exercising, might find their workout to be less satisfying and more rigorous than people who had eaten before exercising.