Asked by: Ciaran Scanlon, Kildare, Ireland
The evidence on this is conflicting. Long-term studies with large sample sizes have found a correlation between artificial sweeteners and weight gain, but these tend to rely on diet questionnaires, which aren’t accurate. They also can’t say whether, for example, diet soda makes you fat, or overweight people are more likely to drink diet soda.
A 2016 report by health charity Cochrane evaluated the results of lots of more rigorous short-term trials, and concluded that artificial sweeteners actually help with weight loss by replacing sugar calories with non-calorie alternatives.