The single biggest predictor of obesity is low income

This evening I watched the documentary, Food, Inc., which exposes huge flaws in our food system and explains why unhealthy food is cheaper than healthy food (see this in-depth post).

Somewhere near the middle of the documentary, they flashed the statement, “the largest predictor of obesity is low income” and a lightbulb went on in my head. Was it true? I immediately logged onto my university library website and did some research to confirm if there was evidence to support this theory. There is, and, in fact, there is so much and it is so conclusive that it’s disturbing I hadn’t heard of it before (see here for lots of links).

We often look at overweight or obese people with condescension, mainly because we think that being overweight is caused by a lack of willpower (see this forum discussion). But is it really? And if a lack of will-power is involved, then what causes this lack of will-power?

One might ask, does a child choose to be born to an unmarried mother? In general, do people choose to be poor? Do they choose to be uneducated? Can will-power alone change these things? Metaphysical murmurings aside, the answer to these questions is obviously ‘no’.

My journey to healthful eating

I grew up with a single mother and I can tell you that if Walmart had been around when I was a child, my mother would have done all her grocery shopping there to pinch our pennies. A quick look in any Walmart ‘grocery’ aisle will clearly show you a multitude of extremely cheap, heavily processed, high-energy, low-nutrition ‘foods.’

There wasn’t a Walmart when I was a child, but there was still plenty of 5/$1.00 mac&cheese, .10 cent ichiban, canned soups, canned ravioli, and wonder(fully-nutritionless)bread. Treats consisted of fast food (my fav was the .99 cent sausage mcmuffin with 21 grams of fat) and anything involving hamburger meat, which was never lean as far as I’m aware of.

All of this changed when I was 18 and my adventurous friend, Aimee, convinced me to go with her to a Hemp Festival in Eugene, Oregon. I met a young man there—a wandering dead-head named Orion—and for three days, we were inseparable; I ate what he ate, much of which I’d never heard of before: kelp, sprouts, lentils and things like that. Everyone walked around that festival calling each other brother and sister. Everyone smiled and welcomed you into whatever chat or activity they were doing. For one of the first times in my life, I felt accepted, even though I was chubby and obviously not a hippy.

I returned to Canada from that festival with a hemp bracelet, crystals of all varieties, body odor, hairy armpits, far fewer brain-cells, far more self-esteem, and a decision to become a vegetarian. The idealistic peace & love feelings faded after a few months, but the Age of Vegetarianism lasted about 7 years for me (til I was 25 and my roommate caught me sneaking a chicken thigh from the simmering pot on the stove!).

Becoming a vegetarian was such an invaluable, life-changing experience for me for one specific reason: half the crap I had been eating my entire life was off-limits. I had to completely retrain my tastebuds, learn how to cook for myself (half the restaurants back then didn’t have veggie options), and figure out what a complete protein was, which I learned was essential when my hair started falling out about 6 months AV.

Many years later, I still struggle with eating healthy and avoiding the pitfalls of ‘cheap’ food. I do know that it is possible to eat nutritious meals on a tight budget (rice and beans are probably the cheapest meal around), but it does take time, education, effort and planning, which might not be available to lower-income people.

If you had a similar childhood full of junk-food, what or who inspired and educated you to become a more healthful eater? If you’d like to learn more about this issue, please continue reading the research that I’ve collected, organized and summarized for you below.

The Evidence

The following evidence is here because my research on forums and blogs indicated that most people, it seems, just want to believe that lack of will-power is the main predictor of obesity. I think this not only disempowers the lower classes even further, but it’s also an ignorant belief based on fear.

After reading these, please give me your informed opinion—has it changed after reading this post? Chances are, if you are reading this post, you are not poor or uneducated, so consider that, and be compassionate.

Do healthier foods and diet patterns cost more than less healthy options? A systematic review and meta-analysis

Download the entire article here.

This 2013 meta-analysis and literature review by Rao et. al from the Harvard School of Public Health (HSPH) is the largest of its kind, and reviewed 27 studies from 10 countries. “This meta-analysis provides the best evidence until today of price differences of healthier vs less healthy foods/diet patterns, highlighting the challenges and opportunities for reducing financial barriers to healthy eating.”

Their findings suggest that for “socioeconomically disadvantaged populations, the relatively higher cost of healthy foods may be an impediment to eating better.”

A meta-analysis is considered one of the most trusted forms of research as it compiles the data from many studies and performs new analysis on the data set as a whole.

Wider Income Gaps, Wider Waistbands? An Ecological Study of Obesity and Income Inequality

Download the full article here.

This study by Pickett et al., published in 2005, studied 21 developed countries and used United Nations data to analyze whether living in a culture with a large gap between the rich and poor, would be correlated to increased obesity.

The results indicated a correlation between the two factors (.48 for men, and .62 for women), and the authors stated, “The psychosocial effects of social position or relative income may contribute to behavioural and/or physiological processes leading to obesity.” As well as, “Increased nutritional problems may be a consequence of the psychosocial impact of living in a more hierarchical society.”

The graph of their correlations is telling, so I included it. See the USA all by itself in the upper right corner? That means it has both the largest gap between the rich and the poor and the largest occurrence of obesity.

Correlations between Obesity and Income Disparity

Obesity in Low-Income Communities: Prevalence, Effects, a Place to Begin

A link to the full article is here.

This literature review by Marilyn S. Townsend, published in 2005, gathered evidence from many studies done and gave 2 strong reasons for why low-income communities in the USA suffer with much higher rates of obesity:

1. compared with middle-income communities, food insecurity plagues many low-income communities, and food insecurity has been shown to be positively associated with overweight among women
2. the majority of food stamp recipients live in low-income communities. Preliminary research has found a positive relationship between women’s Food Stamp Program participation and their body weight

A literature review is considered a more valid form of research because it’s looking at the results of many different scientific studies (it’s not re-analysing the data, but just the results). Of course it is subject to bias, like anything, but it’s more robust than simply one study on its own.

Educational Level, Relative Body Weight, and Changes in Their Association Over 10 Years

Download the full article here.

This paper published in 2000, by Molarius et al., concludes: “Lower education was associated with higher BMI in about half of the male, and in almost all of the female populations, and the differences in relative body weight between educational levels increased over the study period. Thus, socioeconomic inequality in health consequences of obesity may increase in many countries.”

More Research Links

• Obesity, Diebetes, and Social Inequalities, (2009): “Highest rates of diabetes are observed among groups with the lowest levels of education and income and in the most deprived areas.”
• Lower-Energy-density Diets are Associated with Higher Monetary Costs and are Consumed by Women of Higher Socioeconomic Status,  (2009)
• Does Social Class Predict Diet Quality? (2008): “A large body of epidemiologic data show that diet quality follows a socioeconomic gradient.”
• The Economics of Obesity, (2005): “Evidence is emerging that obesity in America is a largely economic issue.”
• This page on the U.S National Library of Medicine has 257 links to research papers on this exact topic. There are 61 free full texts to view.

Some interesting blogs and newspaper articles:

• New York Times article that argues that healthy food can be inexpensive: Real Food Can Be Cheaper than Junk Food by Mark Bittman.
• New York Times article that explores research done at the University of Washington that shows how unhealthy food is more expensive: A High Price for Healthy Food by Tara Parker-Pope.
• Here is a discussion on Inspire, where people give their opinions on the matter and discuss whether they think its true or not, that healthy food is more expensive.