Diet soda is not the low-risk half of the soda aisle

Both pools followed what people already chose to drink, so these are links rather than proof that either drink causes anything. Someone told to watch their weight or blood sugar tends to switch to diet, which would draw this same pattern with no effect from the drink at all. The pooled studies varied widely in their results for several of these outcomes. And these are drink categories, not Coca-Cola and Coca-Cola Zero specifically.

The short trials and the long follow-ups measure different things, weight on one side and disease on the other, so neither one checks the other. The long-term half only watched what people already drank, and people already at higher risk switching to diet drinks would produce the same pattern. This is a joint position from the Korean Diabetes Association and Korean Nutrition Society rather than a new analysis.