New evidence from epidemiological studies may shed some light as to why artificial sweeteners may make you eat more. For example, drinking one can of diet soda per day was associated with a 34% increased risk of developing metabolic syndrome, compared to those who did not drink any carbonated beverages. People who drank the sugar-sweetened versions had a 10% increase in risk.
It’s not clear why artificial sweeteners may make weight gain more likely, but preliminary data suggest that it could be due to the brain’s reaction. One study compared the brain activity of 12 healthy women fed sugar or the artificial sweetener sucralose. Both substances activated areas of the brain associated with pleasant taste, but sugar had a stronger effect in those areas that played a role in expectation and satisfaction. The authors suggest the finding indicates sugar may turn off the desire for more sweetness, but artificial sweeteners do not. Additional calories are needed to get it to stop.
The other side of the argument is that many people lose weight by eating artificially sweetened foods as part of their weight-loss plan. Continued mechanisms are being researched that may link artificial sweeteners with increased food intake. Plans for observational research are being made to determine if an association between diet soda and the development of insulin resistance and other metabolic issues exists.