You're making the implicit assumption that sugar substitutes do reduce the risk of being overweight. At least the first post I found on the topic suggest there

You're making the implicit assumption that sugar substitutes do reduce the risk of being overweight. At least the first post I found on the topic suggest there is evidence of "a positive correlation between regular use of artificial sweetener and weight gain"[0] 0.https://www.publichealthpost.org/research/can-sugar-substitutes-reduce-risk-of-obesity/ https://www.publichealthpost.org/research/can-sugar-substitu...