Wednesday, April 26, 2006

Obesity & health: A case for public intervention?

An article by Dagan Miljkovicn in Choices, a new online journal from the American Agricultural Economics Association, looks at the short-run reasons for anti-obesity policies and the long-run historical evidence suggesting we are are all getting both fatter and healthier! An excellent article, summarised below.

Short-run studies examine obesity and its claimed costs. Long-run studies examine trends in human longevity, and relations between physical characteristics of the population (height, weight, or posture) and health/longevity. Short-run studies find a strong link between obesity and deteriorating health suggesting a case for government intervention. Long-run studies indicate how obesity and overweight may not be associated with health problems. Is obesity then a major health problem requiring policy intervention or not?

Short-Run Perspective

Obesity has been linked to technological change resulting in calories becoming relatively cheaper, while exercise has become relatively more expensive. Individuals have maximized utility subject to this new budget constraint and rationally got fatter. There is no reason to intervene with policy to reduce obesity, since it is merely the outcome of individuals pursuing their own self-interest.

This view assumes well-informed individuals but obesity issues often arise in childhood and children rarely purchase their own food or determine what is for lunch or dinner. And with subsidised healthcare there is a negative externality associated with being obese if there are linked health costs. There are also ‘internalities’ or costs borne by individuals themselves because of high weight arising from self-control or addiction problems: people would like to eat less than they do, but have difficulty doing so. Individuals do not internalise the consequences of current eating for their future happiness. Finally, there is concern because government already intervenes in ways with consequences for weight. Public spending on transportation, parks or education affects the exercise people get. Dietary guidelines affect foods schools serve. Policies on labour supply influencing time available to exercise, time to oversee diet and oversee exercise.

Long-Run Perspective

The short-run studies on possible obesity prevention policies presuppose a benefit from reducing obesity which stems from improved health. Yet these studies ignore long-term health trends and the role obesity plays. Several studies have analyzed long-term health using the longitudinal Gould data set containing age, physical and health characteristics of 23,785 Union soldiers in the1860s, 1880s and early 1900s as well as comparable data for the US Army from the 20th Century.

Analysis of the Gould data set reveals that past populations were shorter-lived, smaller, lighter, and faced a more disease burden in old age. The BMI's of Union soldiers were 23 on average compared to a BMI of 26 for modern soldiers. These studies consider various indicators: height, BMI (a measure of total body fat), waist-hip ratio, the ratio of chest circumference to shoulder breadth etc and various socio-economic and demographic variables. Their findings are that there have been substantial changes in the human frame over the last 100 years as men have become taller and heavier. Controlling for total body fat, men today have less abdominal fat than past populations. Overall the evidence suggests that overweight may not be significantly associated with excess mortality and the risk of obesity on mortality may have decreased.

The theory of technophysio evolution posits that during the last 300 years human beings have gained an unprecedented control over their environment, that set them apart from all other species and previous generations. This has enabled people to increase their average body size by over 50%, to increase their average longevity more than 100%, and to greatly improve the robustness and capacity of their vital organs. Advances in food production technology after 1700, in combination with technological advances in manufacturing, trade, transportation, energy production, communications, or medical research and services all increased average longevity and body size. The specific environmental factors contributing most to the observed declines in morbidity and mortality remains unclear.

Obesity and Overweight: Policy Dilemma?

Increased obesity over the last 20 years has left scientists undecided about the actual effect this has had on the health and mortality of people. Studies using longitudinal data suggest that previous populations, albeit having significantly lower BMI than today's population, suffered from the same chronic diseases that are commonly thought to be caused by being obese. If the government seeks to stop or reverse obesity that may not be to improve health but really to protect people's perceptions of how they should look. This may be a misplaced emphasis.


Jan said...

I agree that the observed improvement in health over the past centuries may be partly due to an increase in body weight (leading to a more solid frame etc). But it is very unlikely to be due to obesity. The relationship between weight and health seems to be nonlinear (hump-shaped), i.e. neither the skinny model-type nor obese people are healthy on average. This would imply that while we should not be too worried about slight increases in average weight we should be worried about the growing proportion of obese people.

rabee said...


My late grandfather who was a cook in the Ottoman army during the First World War told me the following:

“when we saw the English they looked normal, like us. But the Australians were huge. They had very large feet”

Well he was just a bit bigger than my six year old. Mind you he died at what seems to be ripe old age (we don’t know when he was born “third good harvest after the bad one”...)

Have you seen English films from the twenties? People were very small.

I guess Australians, Canadians, and USians, were well nourished in the 1920's but probably not as stout as they are now.

D. Prentice said...


For what its worth, the Icelandic experience (as related by old my housemate) during WWII is consistent with this. When the English occupied Iceland (which the locals were not happy about but could do little about), they did not seem particularly physically impressive. But when the US army arrived (interestingly before Pearl Harbour, according to my housemate), they were physically more impressive and complaints of the sort experienced in Australia started.

My housemate though also noted - that the Americans that arrived were probably among their best soldiers, which was unlikely to be the case for the English (who perhaps had other priorities).