34.9% of US adults are obese
First the stats. According to 2014 figures from the US Centers for Disease Control & prevention (CDC), 34.9% of US adults are obese (defined as having a BMI of 30+). The Midwest has the highest prevalence of obesity (30.7%), followed by the South (30.6%), the Northeast (27.3%), and the West (25.7%).
The map is based on the latest (2014) data.