One problem I have with this study is that they didn't seem to record the types of carbohydrates and types of fat people were eating.
There are big differences among sugar, refined starches such as white flour, and whole grains.
Also, there is a big difference between animal fat and vegetable fat.
All of these different nutrients are metabolized differently and have different effects on weight and health.
If the "high carb" people ate lots of sugar and refined starches, they would not be healthy.
If the "high fat" people ate lots of olive oil and not much animal fat, they would be healthy.
Bottom line is that you can't tell much from this study.