Heavy Americans who drink diet beverages rather than those sweetened with sugar appear to eat more, according to a study released on Thursday that raised questions about the role lower-calorie drinks play in helping people lose weight.
Researchers at Johns Hopkins University analyzed data from a U.S. survey of 24,000 people over a period of 10 years. People who were overweight or obese generally consumed the same amount of calories a day no matter what they drank, but those who chose diet drinks got more of those calories from food.
If you are overweight* then you are consuming more calories: thus if you get fewer of those calories from soda pops then you will be gaining more from other sources which are not soda pops.
This seems reasonably obvious really.