You already know that eating junk food won't help you lose weight, but knowing why might make it easier to pass up. Processed carbs and sugary foods such as ice cream, cookies, muffins, crackers, bagels, and white bread spike your insulin levels, which causes weight gain. Keeping your insulin levels low will help you reduce your overall body fat percentage, and that means belly fat.
Aside from being high in carbs, these foods also tend to be high in calories. That's not the only problem, though — eating them doesn't offer your body any nutrition, so you end up feeling hungry, which makes you eat more. Eating sugary foods also increases your cravings for them, again, making you eat more. If you cut down on these types of food, you'll definitely notice a difference in how you feel and how your belly looks.