If you can take one of those elements out of the cycle, you break the cycle. Those cultures stop the cycle (or more accurately, don't start it, although that's changing with time as the SAD diet takes over the globe). It's just not that sugar has to be bad, or carbohydrates are always bad, but if you were raised over-eating sugar and have PUFA related inflammation, they aren't going to help you lose weight or feel better.
At the end of the day, some people just think it's all about "calories in and calories out" but it's a rather myopic look on it. At some point we need to look at the type of calories people are consuming (starting a a young age and as they get older) and try to understand that different foods and different impacts to the body and its hormones (like insulin) and that the typical standard American diet loaded with sugar, no fiber and shitty oil (causing inflamation, which causes blood sugar spikes) are causing metabolic issues and putting a ton of people into a broken state ("metabolic syndrome").