There’s considerable controversy over whether obesity in and of itself leads to higher mortality rates and illness. It is highly correlated with a basket of diseases, including diabetes and hypertension, however that could be due to an underlying factor.
The interesting thing is how obesity correlates to income in the West, especially in the U.S. This graph shows state level data, ordered by median household income in decreasing order, charted against the states’ obesity, diabetes, and physical inactivity rates. I left out hypertension for visual clarity (it tracks with obesity and physical inactivity). Physical inactivity is the percentage of CDC survey respondents who reported that they did not engage in any physical activity in the previous month. Not sure how they defined physical activity.
Diabetes appears to rise slowly as household income decreases, while obesity and inactivity rates rise more steeply as income decreases. There are problems with this data, e.g. wild heteroskedasticity - really, comparing California and Wyoming?) but I would venture that the overall relationship is representative.