> Seems you really want to do something against obesity and you are ready to accept quite a lot of collateral damage by punishing people with extra tax who don't need to be protected/helped at all.

Actually, quite the opposite. People who don't consume foods with lots of added sugar are already healthier and wouldn't end up paying a lot more for their food. The people who are consuming lots of added sugar are contributing to the growing problem of chronic diabetes. Right now we are all being punished with higher health insurance premiums and reduced benefits, because more and more people are having to go on insulin, alpha-glucosidase inhibitors, metformin, etc. You know how you reduce health care costs and help people? You prevent disease from starting in the first place, but that means instituting programs and incentives that actually change people's behavior. If you have a sugar tax whose funds go into programs to encourage healthy eating, working out, etc., then that is a net win for society, since over time less and less people will develop type 2 diabetes and other illnesses caused by obesity. This is not a new concept and has been successful before. Most notably in the form of cigarette taxes. (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3228562/)

> I on the other hand believe that the sugar itself is a minor problem, the bigger problem is the lack of physical activity and micro-nutritients.(sic)

Increasing physical activity and micro-nutrients are great goals, but do not play a large part in the obesity epidemic. The over-consumption of high caloric food is the root cause. It takes a lot of time to lose weight through physical activity. Run 30 minutes on treadmill and maybe you will lose 300 calories? That probably won't even offset half of many people's lunch calories. Again, the majority of calories are lost through just breathing out. (https://www.youtube.com/watch?v=nM-ySWyID9o) It's a much easier and more effective strategy to reduce the amount of calories coming in. That's why intermittent fasting has become so popular.

> But that's my personal assessment and as your study says, we don't know enough yet how much impact the different factors really have, so no one really knows. However, increasing bureaucracy based on not well understood concepts is probably a fairly bad idea.

Just because we don't fully understand the role of all the biochemical processes involved in insulin resistance, obesity, etc. doesn't mean we don't understand the broader causes and the changes that should be made to diets to improve health outcomes. Your argument is similar to saying just because we don't understand all the mechanisms that cause the earth to heat up we shouldn't try and reduce CO2 emissions. It's nonsensical.

> Sorry that doesn't make any sense. If I ate 2500 calories today and 500 of them were "excess" (because daily I burn only 2000), then which of the 2500 are now your so-called "excess calories"?

Sure, it does. As you yourself stated "added sugar has zero good micro-nutrients", by definition these are excess calories that you don't need. If we need to reduce people's consumption of calories then the first to go should be the ones that aren't providing any benefit.