Dear Dr. Roach: My family members drink mega amounts of diet pop, including the kids, ranging from age 3 to age 10. All the adults have serious weight problems. They say they have to drink something besides water. What comments do you have? A.H.
Answer: There remains a controversy about the effect of diet soda and nonsugar sweeteners on weight loss. Observational studies (those that correlate behaviors with outcomes) suggest that greater consumption of diet sodas is associated with a higher risk of obesity. There are several possible explanations for this, including that overweight people are more likely to drink diet soda to try to lose weight. However, there also is evidence that drinking diet soda increases appetite and changes the way we perceive taste.
Some interventional studies, generally considered the strongest evidence, have shown that people whose diet is changed to include diet sodas experience weight loss. Unfortunately, there is evidence of bias in these kinds of studies, possibly related to support by the industry.