Yes, artificial sweeteners have repeatedly been shown to cause more weight gain than equivalent sugar, and human studies back that up.

Here is a brief survey of studies showing the effect in humans:

http://time.com/3746047/diet-soda-weight-gain/

None of the studies in that survey actually support the claim I questioned though, which is specifically about insulin response in humans. Further, they don't even support your claim that artificial sweeteners cause _more_ weight gain than equivalent sugar.

imo a big problem with these kinds of studies is the huge number of confounding factors. They tend to be studies that select participants who report drinking diet soda and those who report not drinking it, without taking into the account the fundamental lifestyle differences between the two. This is also why I'm interested in specific, measurable things that are known to cause problems, such as insulin response.

It is very common for overweight people to replace sugary soda with diet soda without making any other lifestyle changes. It is unsurprising that this doesn't yield positive results over the long-term. People who report drinking no soda, diet or otherwise, are likely already leading healthier lifestyles than those who report drinking diet soda regularly. Without controlling for these factors properly all that's really being said is that "healthier lifestyles are better for controlling weight".

I agree that diet soda is probably worse than no soda, but I haven't seen any evidence to support the idea that diet soda is worse than sugary soda when consumed in otherwise identical diets.

> shown to cause more weight gain than equivalent sugar

The article you link doesn't say that. First, almost nothing in it even talks about real sugar. Second, it specifically starts with in the first paragraph "doesn’t prove that diet drinks and artificial sweeteners cause weight gain" and then goes on to have more paragraphs of speculation on correlation. But nothing mentioned in that article demonstrates a causal effect, and definitely not more than equivalent sugar. There's a lot of "may be" and "may cause" in there. Emphasis on may.

The diet soda doesn’t “cause” weight gain. At most it leads people to overindulge because they did one thing “healthy”. Saying diet soda causes weight gain is like saying eating at Subway causes weight gain because people go there and eat pizza, ice cream and cookies because they think it’s healthier.

I don't have cites. But my bro assisted research studies at uni back in the late 80s that established this connection. The notion at the time was the body produces insulin to match the perceived sweetness, vs the actual amount of carbs to metabolize. The kicker is the excess insulin then works on otherwise useful protein. So in effect, artificially sweetener is worse than just straight sweet.

I've never read anything to contradict this. I have no idea what the state of the art is today.

Also, I do know it'd be a mistake to generalize insulin response across non-diabetic, type 1, and type 2 people.