Monday, September 9, 2019

Lifestyle habits in the states of the USA

People throughout the western world are constantly being reminded that modern lifestyles have many unhealthy aspects. This is particularly true of the United Stats of America, where obesity (degree of over-weight) is now officially considered to be a medical epidemic. That is, it is a disease, but it is not caused by some organism, such as a bacterium or virus, but is instead a lifestyle disease — it can be cured and prevented only by changing the person's lifestyle.

The Centers for Disease Control and Prevention (CDC), in the USA, publish a range of data collected in their surveys — Nutrition, Physical Activity, and Obesity: Data, Trends and Maps. Their current data include information up to 2017.

These data are presented separately for each state. The data collection includes:
  • Obesity — % of adults who are obese, as defined by the Body Mass Index (>30 is obese)
  • Lack of exercise — % of adults reporting no physical leisure activity; % of adolescents watching 3 or more hours of television each school day
  • Unhealthy eating — % of adults eating less than one fruit per day; % of adolescents drinking soda / pop at least once per day.
The CDC show maps and graphs for these data variables separately, but there is no overall picture of the data collection as a whole. This would be interesting, because it would show us which states have the biggest general problem, in the sense that they fare badly on all or most of the lifestyle measurements. So, let's use a network to produce such a picture.

For our purposes here, I have looked at the three sets of data for adults only. The network will thus show states that have lots of obese adults who get little exercise and do not eat many fruits and vegetables.

As usual for this blog, the network analysis is a form of exploratory data analysis. The data are the percentages of people in each state that fit into the three lifestyle characteristics defined above (obese, no exercise, unhealthy eating). For the network analysis, I calculated the similarity of the states using the manhattan distance; and a Neighbor-net analysis was then used to display the between-state similarities.

Network of the lifestyle habits i the various US states

The resulting network is shown in the graph. States that are closely connected in the network are similar to each other based on their adult lifestyles, and those states that are further apart are progressively more different from each other. In this case, the main pattern is a gradient from the healthiest states at the top of the network to the most unhealthy at the bottom.

Note that there are seven states separated from the rest at the bottom of the network. These states have far more people with unhealthy lifestyles than do the other US states. In other words, the lifestyle epidemic is at its worst here.

In the top-middle of the network there is a partial separation of states at the left from those at the right (there is no such separation elsewhere in the network). The states at the left are those that have relatively low obesity levels but still fare worse on the other two criteria (exercise and eating). For example, New York and New Jersey have the same sorts of eating and exercise habits as Pennsylvania and Maryland but their obesity levels are lower.

It is clear that the network relates closely to the standard five geographical regions of the USA, as shown by the network colors. The healthiest states are mostly from the Northeast (red), except for Delaware, while the unhealthiest states are from the Southeast (orange), with Florida, Virginia and North Carolina doing much better than the others. The Midwest states are scattered along the middle-right of the network, indicating a middling status. The Southwest states are mostly at the middle-left of the network.

The biggest exception to these regional clusterings is the state of Oklahoma. This is in the bottom (unhealthiest) network group, far from the other Southwest states. This pattern occurs across all three characteristics; for example, Oklahoma has the second-lowest intake of fruit (nearly half the adults don't eat fruit), second only to Mississippi.

These data have also been analyzed by Consumer Protect, who offer some further commentary.


This analysis highlights those seven US states that have quantitatively the worst lifestyles in the country, and where the lifestyle obesity epidemic is thus at its worst.

These poor lifestyles have a dramatic impact on longevity — people cannot expect to live very long if they live an unhealthy lifestyle. The key concept here is the difference between life expectancy (how long people live, on average) and healthy life expectancy (how long people people remain actively healthy, on average). This topic is discussed by the The US Burden of Disease Collaborators (2018. The state of US health, 1990-2016. Journal of the American Medical Association 319: 1444-1472).

In that paper, the data for the USA show that, for most states, healthy life expectancy is c. 11 years less than the total life expectancy, on average. This big difference is due to unhealthy lifestyles, which eventually catch up with you. As a simple example, the seven states at the bottom of the network are ranked 44-51 in terms of healthy longevity, at least 2.5 years shorter than the national average. (Note: Tennessee is ranked 45th.)

You can see why the CDC is concerned, and why there is considered to be an epidemic.


Some of the seven states highlighted here have other lifestyle problems, as well. For example, if you consult Places in America with the highest STD rates, you will find that they are listed as five of the top ten: 2: Mississippi, 3: Louisiana, 6: Alabama, 9: Arkansas, 10: Oklahoma, 31: Kentucky, and 50: West Virginia.

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