The problem is that switching to diet soda may change behavior in ways that negate the effect of calorie reduction. The average of calories on sweetened sodas is about 100 cal or 12oz. per serving. A few sodas a day add up to a lot of empty calories or may lead to weight gain.
A small amount of empty calories is okay, but most people eat far more than is healthy. It is important to limit empty calories to the amount that fits your calorie and nutrient needs. You can lower your intake by eating and drinking foods and beverages containing empty calories less often or by decreasing the amount you eat or drink.
Based on the study conducted by Qing Yang in 2010 which was published in Yale Journal of Biology and Medicine, he found out that sugar substitutes only partially stimulate the food reward brain centers, so the body still craves additional nutritive food rewards.
Non-nutritive sweeteners, so called because they contain no macronutrients and thus no calories, are a staple of diet foods and especially diet beverages and can be helpful in weight management. However, some research indicates that the use of these sweeteners may actually lead to weight gain. On their own, they don’t affect blood sugar, but foods that contain artificial sweeteners may also contain ingredients that do affect your blood sugar.