The people that saw the most weight loss were those that also claimed the supplements reduced their appetite looks like supporting evidence for the placebo/weight-tracking effect to me (and if there is an actual mechanism linking potassium intake and appetite, it might be one which only affects the subset of people in a study with a high dropout rate that had something particularly wrong with the levels of potassium in their body and regular diet)

The dropout rate is significant too, both in general and in the specific case of this being a self-selecting sample of readers of a blog promoting fringe theories around weight loss(1). One way to get a statistically significant sample for a weight loss treatment being apparently effective is for people to be most likely to drop out of an experiment without submitting any further data the day the scales give them the disappointing news that they've put the pounds they lost back on again.

Potassium is apparently already marketed as a weight loss supplement, so I'm guessing there are other studies of varying but generally better quality floating around though...

(1)its rather tortuous reasoning why America's obesity rise can't be linked to the rise in average calorie consumption has been posted on here before...

> why America's obesity rise can't be linked to the rise in average calorie consumption

I think most (certainly not all) folks agree with the general "people gain weight because they're eating too many calories". I think the interesting question is "Why did people seem to start doing this now?"

Ice cream and butter and so on are not new inventions. We as a species have never hurt for desserts or calorie dense foods. So what change is it in our environment which seems to be causing the increased intake in calories?

And some of the usual suspects that get trotted out: sweetened soft drinks served in huge quantities for basically free, extremely processed foods with surprising calorie density that still leave you hungry, maybe changes in some of the ingrediants we're using, so on.

I suspect, given that lots of intelligent people have worked really hard on this and haven't landed on an obvious single answer, that it's a big combination of things. The more I talk to obese people the more I'm convinced there's some sort of sociological or psychological element as well as a food element.

HFCS and seed oils were not consumed in quantity by humans 40 years ago. These seem to be linked to both inflammation and enlarging waists.

To be honest, 'why, in the century in which most people had cheap, reliable food sources and motorised transport for the first time in history and many stopped doing manual labour did obesity start going up in many countries where people benefited from these changes?' doesn't seem like a question likely to have an especially counterintuitive answer. Ice cream may have existed in various forms for centuries, but the average person didn't eat 20L of the stuff every year before effective and near-universal refrigeration. (The same blog dismissed the standard claims around less healthy refined foods and people not needing as many calories because they lived more sedentary lifestyles anyway...)

I'm sure there are individuals with metabolic issues that aren't related to their diet and it's not impossible that the "contaminants" this blog is obsessed with play some role. But I also think that sunspot activity plays some role in climate, and I wouldn't expect to stunning breakthroughs in sunspot science from a climate-skeptic blog motivated primarily with proving that the major step change over the last century that's consistent with the theory and the data can't possibly have made much of a difference...

What changed between the 1970/80s and now though?

In the case of the US, the data shows an increase of a few hundred calories in mean calorie intake, not necessarily distributed evenly...