It is entirely unclear how any controls were implemented. They say "after controlling for lifestyle factors" but do not say which factors nor how they controlle

It is entirely unclear how any controls were implemented. They say "after controlling for lifestyle factors" but do not say which factors nor how they controlled for them. It is entirely possible, perhaps even likely, that diet beverages are simply a proxy for some other factor. Maybe even just weight. To wit: "This association may also be contributed to by rising blood pressure and sugars that were not yet diagnosed as hypertension or diabetes but warranted weight loss," thus leading the women in the study to take up diet beverages, said Dr. Keri Peterson, medical advisor for the Calorie Research Council, an international association representing the low- and reduced-calorie food and beverage industry. This possibility makes the implication that there is some causal relationship pretty tenuous. This question: "What is it about these diet drinks?" asked lead study author Yasmin Mossavar-Rahmani ... might well be answered with, "nothing at all actually". (edited for quotes because I keep forgetting this is not markdown)