Those undergoing bariatric surgery have made a commitment to drastically reduce the added sugar in their diet and this dietary change alone will have a positive impact on their health. But what about the use of sugar substitutes—calorie free packets added to water bottles, sugar free creamer in coffee, sugar free popsicles, a cup of no-added-sugar hot cocoa, no-added-sugar pumpkin pie to celebrate Thanksgiving, and sugar free cheesecake at birthday time? The latest headlines would have you believe that sugar substitutes cause weight gain, diabetes, cancer, dementia and strokes; but what does the research tell us?
A study released this July spurred headlines that diet drinks caused weight gain. The study asked people about their diet and then tracked their health for years. They found that those drinking diet drinks had gained more weight than those not drinking diet drinks. The theory is that sugar substitutes trigger sweetness receptors in the brain, setting the body up to receive a substantial calorie load. When the calories don’t arrive, the body, looking for those calories, increases hunger, causing people to eat more and they gain weight.
Other studies don’t support this theory, however. One study found that although people tend to gain weight over time, people gain less weight when drinking diet drinks vs sugary beverages. Another found that people ate fewer calories when snacking on cream cheese sweetened with stevia and crackers than those whose cream cheese was sweetened with sugar. Those drinking diet beverages ate fewer desserts than those drinking water, found another study.
Could there be reasons other than drinking diet drinks cause weight gain for the association between drinking diet drinks and gaining weight in the July study? Perhaps people found themselves gaining weight (which does happen to most over time) and switched to diet drinks in an effort to lose weight?
Conclusion—the science tells us that there is strong evidence that drinking sugary drinks causes weight gain in children and adults and there is very weak evidence that diet drinks cause weight gain.