From What Works What Doesn't To be fit you need to stop letting myths like these hold you back.
1. Walking is not as effective as running. Sure, you'll burn about twice as many calories running for 30 minutes than walking for 30 minutes. But if a runner and a walker cover the same distance, they burn about the same number of calories. So if you're willing to take the 'slow route,' you'll likely lose just as much weight. In fact, studies have proved that how long you exercise matters more than how hard you exercise.
2. Exercise increases hunger It's a common misconception: If you burn hundreds of calories during a workout, you'll end up eating more. But research shows that exercise has no effect on a person's food needs, with the exception of endurance athletes who exercise for two hours a day or more. In fact, research shows that exercise often suppresses hunger during and after the workout.
3. It doesn't matter where your calories come from Calories are not created equal. First, some foods (in particular, proteins) take more energy to chew, digest, metabolize, and store than others. Others (such as fats and carbohydrates) require fewer calories to digest and store. Second, different food types have different effects on your blood sugar. Refined carbohydrates (think white bread, cookies, and fruit drinks) raise blood sugar levels dramatically, which encourages fat storage, weight gain, and hunger. Fibrous foods like apples, as well as proteins, raise blood sugar less, making them friendlier to your waistline. Finally, foods that contain a lot of water, such as vegetables and soup, tend to fill the belly on fewer calories, so you'll stop eating them way before you stop eating more calorie-dense foods.
4. Diet alone is enough for sustained weight loss You'll lose weight in the short term by slashing calories, but experts say exercise is what keeps pounds off for good. Exercise burns calories, of course. It also builds muscle, which takes up less space than fat. Muscle tissue also requires more calories to sustain it than fat tissue does. In other words, the more muscle tissue you have, the more calories you'll burn at rest. In fact, some studies suggest that over the long term, if you had a choice of eating consistently less or exercising consistently more, exercise would be the better weight-loss choice.
5. There is no best time for exercise If you're simply walking to get healthy or take off some weight, it doesn't matter when you do it, as long as you do it. But if you're an athlete looking for the best-quality workout, choose the late afternoon, when body temperature is highest. Muscles are warm, reaction time is quick, and strength is at its peak. If you push yourself harder as a result, you will burn more calories.