A can of soda is made up of hundreds of calories—as much as what is often recommended for an entire meal. Except you cannot just have the soda pop in place of your plate of food. You won’t be gaining any amount of nutrition from drinking a can of soda. Also, you are not likely to end feelings of hunger when you down a can of the sweet liquid. So you are still going to feel the need to eat other foods—adding to your number of consumed calories for the day.
Eating a big bowl of macaroni and cheese might not be the best thing for you if you are on a diet. However, it at least can give you some nutrition, and help you to feel full momentarily. Therefore, it is a lot less devastating to your diet than a can of soda.
If you currently drink soda routinely with all of your meals, you can easily lose weight just by getting rid of that soda-drinking habit. For losing weight, it is best if you could just switch to drinking water. However, if that is not a possibility for you at this time, switching to tea or milk would also help.