It almost reads like an April Fools Day article.  A new UC Davis study has found that more obese people have minimum-wage jobs by demographic, adding to growing evidence that being poor is a risk factor for unhealthy weight.

So minimum wage jobs cause obesity? No, but if researchers are going to make silly correlations they could as easily have made that one. The researchers instead want to make the case that being poor somehow makes people fatter. The reasoning is that after mankind spent 2,000 years finding ways to make food cheaper and more plentiful - a Utopia to poor farmers before the latter third of the 20th century - people began to eat more of it.  But not always the healthy kind, more like the kind they could make a profit at.

So 100 years ago you had to be rich to be fat but now you have to be rich to be thin.  

The researchers reason that it is perhaps that poor people live in less-safe neighborhoods and have less access to public parks so they walk less - they seem to think that all poor people live in cities.  They also contend that healthy and/or lower-calorie foods tend to be more expensive.  

The solution to all those problems?  Raise minimum wage.

Of course.   

What researchers don't realize but everyone else does is that giving people access to more money does not give boost anyone at all - when college education became a 'right' and loans were unlimited to allow everyone to get one (because people with college educations make money money) everyone was able to get one and college tuition spiked, benefiting no one except colleges.  

When home ownership became a right and banks had to document in detail why they did not give someone a loan, loans became unlimited and competition for houses went up and poorer buyers found themselves competing in a price range with a lot more people and costs spiked - because there are a lot more people after $200,000 houses than $2 million ones.

So it goes with simply raising minimum wage and thinking people will eat healthier.  Researchers tend to only believe in the miracle of capitalism when it will justify some bit of social engineering that otherwise makes no sense.  Capitalism will make food prices low, for example, but capitalism cannot be allowed to set prices for wages of employees.  But if wages are higher ... well, you know the rest.

"The correlation between obesity and poverty-level wages was very strong," said Paul Leigh, senior author of the study and professor in the UC Davis Center for Healthcare Policy and Research.   But it's just a correlation.  What he does not want to say is that minimum wage jobs cause obesity - that is just me - but if we're going to map data to the cultural topology we like I can do it also.

"The outcome leads us to believe that raising minimum wages could be part of the solution to the obesity epidemic. Doing so could increase purchasing power enough to expand access to healthier lifestyle choices," Leigh said.

Yep, if you pay people more by federal mandate rather than capitalism, capitalism will find a way to make healthier food cheaper.  But, wait, healthier food is more expensive to produce, right?  Free range cows cost a lot more than regular old cows.  If more people are producing only 'healthier' foods and taking more land to do it, that means less cheap foods also and the costs of those will go up, meaning poor people will ... starve.   I suppose that is better than being fat but not really the goal our forefathers in science set out to achieve.

How did he make what you and I see as funky correlation-causation arrows into causal ones when no controlled experiments (you know, as in science) can be done?   Instrumental variables.  Economics and social sciences people love those.  What are they?   Instrumental variables mean if you want to establish a causal relationship between two things, you introduce a third one which only affects the first through its effect on the second.    

Easy, right?

Maybe not.  Let's do it this way.   I want a certain amount of Money (M) and I want to see how Blogging (B) impacts that.   I introduce a third variable Time (T) as my instrumental variable because I want to see if T related to B causes more M.   Indeed I found it does and you did too; the more blogs you write, the more money you make.    Let's pitch it to Journal of Occupational and Environmental Medicine.

But wait, you may still see some flaws in that, but this is why you are not a health policy analyst.   You might think M could also come from other places, meaning the relationship between M and B is coincidental to T; one great article may perform better than 30 bad ones, for example.

In the case of obesity and income, we at least know he has one independent factor that should not be caused by obesity - minimum wages.   People will insist today that gender or color results in a lower wage with a straight face but no one can claim $7.25 an hour minimum wage is due to obesity.

Says Leigh, "After adjusting for inflation, minimum wages have been stagnant or falling over the past three decades, placing most full-time workers near the poverty line. It is also during those same three decades that we have seen the prevalence of obesity soar."

But ... but ... everyone is more obese than 30 years ago.    I could establish a causal relationship between more cats and minimum wage too.  But here is the data.   People earning the lowest wages were more likely to have weights in the obese range - BMIs of 30 or greater. People living in the southern United States – where state minimum-wage levels are among the lowest – were more likely to be obese than people in other regions.

Kind of tangential, right?  

But the issue is obesity and that is caused by eating a lot of calories.   If people are close to the poverty line and can't afford 'healthy' food, a seeming improvement over a century ago when they could afford no food at all, what does that have to do with them eating so much of it?

And how can we insure that people will use their newfound money on healthier food if the minimum wage is raised?  What if they go buy a Blu-Ray player or something?  Well, we can't dictate that.   If people can't control themselves and eat too many Big Macs now they sure won't have more discipline when they have more money.  More money might make obesity go up even more.

In fairness, and Leigh had to do know Big Media would run with this and science blogging would make fun of it, he acknowledges the limitations, and he points out the sample as the primary one; 85% of the people were men and 90% were Caucasian.   So instrument variables could show the minimum wage should only be raised for men and white people.

"Future research should address wage and obesity correlations among samples that include more African-Americans, Hispanics, Asians and women," said Leigh. "Obesity is a complex problem that likely has multiple causes. The more we can pinpoint those causes for specific populations, the greater chances there are for reducing its impact."

Well, yes, but in every study of obesity during the last 70 years, regardless of genetics, income or where they lived, people who burned more calories than they consumed lost weight.

Science has an explanation for that.

Citation: Kim, DaeHwan PhD; Leigh, John Paul PhD, 'Estimating the Effects of Wages on Obesity', Journal of Occupational and Environmental Medicine,  May 2010 - Volume 52 - Issue 5 - pp 495-500 doi: 10.1097/JOM.0b013e3181dbc867


NOTES:

(1) In gathering data to assess through instrumental variables, the team started with the Panel Study of Income Dynamics. This longitudinal, representative sample of people in the United States includes information on height and weight, which were used to calculate body mass index (BMI), in addition to demographics and earnings. The researchers isolated data collected in 2003, 2005 and 2007 from 6,312 full-time workers in over 40 states who were 20-to-65 years of age and identified themselves as heads of households. State-established minimum-wage data for those same three years was obtained from the U.S. Department of Labor.