What is in Diet Coke that increases my appetite? Is it the Nutrasweet, the caffeine, both, or is it a psychological thing?
— Hungry after Diet Cokes
Dear Hungry after Diet Cokes,
People have varying reactions to diet sodas. Whether they're due to the aspartame (brand name, Nutrasweet), or something else, is a good question. Many studies have investigated the effect aspartame has on appetite because some people find it increases the desire to eat, while others notice it suppresses it. Questions remain because the results are not consistent. Even when blood sugar levels were measured after drinking an aspartame-sweetened beverage, some levels increased, others decreased, and the rest remained unchanged.
Most likely the caffeine in the soda isn't what's making you hungry. Caffeine is generally regarded as a mild appetite suppressant. Don't get any ideas here, because it is not successful in weight control. Caffeine's effect on appetite is short lived. Studies on this subject have consistently shown that caffeine is not an effective weight loss aid. In terms of caffeine content, a 12-oz. can of diet cola typically has about 35 mg of caffeine while a 12-oz. cup of brewed coffee has about 150 - 200 mg.
Chemical effects aside, here's another possibility: lots of people substitute a diet soda for a snack, or even worse, a meal. Ignoring your hunger denies your body the energy it needs. Instead of feeling satisfied from the soda, your need to eat becomes more pronounced. It may not be the aspartame, but the lack of food that's driving your appetite. Take notice of when the diet soda makes you hungry. If it has been a few hours since you've eaten, you probably need some nourishment. Instead of having that diet soda, try to eat a healthy and satisfying snack (or meal, if a longer time has passed).
If you find that the diet soda makes you hungrier when you're having it with a meal, consider whether your meal is filling. Substitute water for the diet soda and see if you feel the same way. If you're still hungry afterwards, then you need to re-work your meal. Either way, it's a good idea to cut down on the diet soda. Try water or seltzer with a spritz of juice for added flavor instead. Better yet, some milk or juice may help to fill you up and provide some valuable nutrients.