There are lots of possible issues with this chart, but it is pretty stark.
A few random thoughts:
- It might not be the people eating unhealthy amounts of sugar who cut back on it. I was never obese and I radically cut back on my sugar intake.
- Sugar may have been highly correlated with other similar substances that people didn't cut back on. I'm thinking about other refined carbs, primarily.
- There may simply be a lag and obesity will start declining as a result of lower sugar consumption.
- It does look like the rate of obesity increase decreased slightly (lower slope), so maybe the issue is just that sugar intake is still too high, but the relationship is correct.
What do you think explains this divergence?