Reddit user zonination has created a comprehensive chart that shows every state's obesity rates from 2003 to 2015. If you take a look at the big picture, you can see that most every state has trended toward being more obese. But after a closer look, it's clear that some states are still much more fit than others. Colorado in particular is an outlier, both in 2003 and 2015.
Note that each region is ordered from top to bottom with the highest obesity rate at the top and the lowest obesity rate at the bottom. And of course the lighter the square, the higher obesity rate.
It will be interesting to see how these trends continue, as we learn more about fitness and nutrition. Check back in another 15 years and this chart will show a whole different picture.