All that you have read on losing weight by exercising is not entirely hogwash. Activity is essential to keep weight within limits and to live a healthy life devoid of heart attacks, diabetes and what not, looming over your visceral fats and muffin tops. But, you need to keep your gob shutters down more often than you flex your muscles.
Consider this scenario: You are an overweight man who consumes 1, 000 + calories per day and exercises for 30 minutes whenever there is time. You try this regimen for a month and see not the slightest drop in weight. Why would you? Exercising for thirsty minutes (jogging or swimming) will at the most burn 350 calories, which is far less than the number of calories you ingest. Moreover, you probably do not even keep up a strenuous exercise regimen, day in and day out.
While exercising is a good way to give your mind the motivational fodder it needs to thrive, depending entirely on it for weight loss has many loopholes.
This is not to say that exercise has no role to play at all. It does to a great extent when added to diets. Dietary changes are the biggest factors to losing weight.