Can Exercising & Not Eating Make You Lose Weight?

You probably know that the most effective way to lose weight is to eat fewer calories while burning more calories through exercise. Although you might think that exercising vigorously and not eating at all can make you lose weight even faster, that doesn't represent a wise approach. You need to take in some nutrition in order to support your exercise routine, and you actually can start to burn muscle tissue instead of fat if you don't eat enough while exercising.

Losing weight usually involves a combination of exercise and decreases in the amount of food you consume. If you burn about 500 calories each day in exercise and drop another 500 calories each day from your diet -- ideally in the form of empty calories such as chips and fast food -- you'll lose about 2 pounds each week. Exercising more and cutting more calories will lead to additional weight loss.

If you consume fewer than about 600 calories a day -- or if you stop eating altogether -- you'll be fasting, not dieting. People fast to lose weight and for spiritual reasons. Short-term fasts -- for three days or so -- are safe, but longer-term fasts may not be safe. Fasting also slows your metabolism, making it difficult for you to keep up an exercise routine.

If you fast and try to exercise, you risk your body burning muscle tissue instead of fat tissue for fuel. You'll lose weight this way, but you won't be getting rid of your stored fat deposits. During an extended fast, you also risk several serious health effects, such as problems with your heart rhythm, kidney stones, liver damage and anemia. In addition, people who fast or eat too little and then engage in vigorous exercise may have exercise addiction or an eating disorder.

If you want to lose weight through diet and exercise, you can do it -- just tone it down so you're eating enough to provide the energy you need for your workouts. You should consume a balanced diet with plenty of high-quality carbohydrates such as whole grains and fresh produce. In addition, your workouts should last about three-quarters of an hour almost every day of the week. That way, you can lose weight without starving yourself.