I have posted a number of previous notes about obesity (see, for example: No Nation Has Lowered Its Obesity Rate in 33 Years) because I think that it's one of the greatest health threats facing the U.S. as well as around countries. I came across an interesting article that speculates about the primary cause for obesity around the world (see: What’s Behind the Obesity Epidemic? Easily Accessible Food, and Lots of It) and below is an excerpt from it. It's worth reading because of the abundance of evidence it provides for the theory that the cause of most obesity is that food is to inexpensive and accessible.
Among the American public and even some policymakers, it has become conventional wisdom that poverty, a dearth of supermarkets, reduced leisure time, and insufficient exercise are key forces behind the U.S. obesity epidemic. Conventional wisdom is an unreliable guide, however, and in this case, much of it is wrong: The epidemic actually coincides with a falling share of income spent on food, wider availability of fruits and vegetables, increased leisure time, and more exercise among the general population. Of course, there are differences between individuals, but we need to explain the change in obesity over time, not why people differ. Some differences in body mass index (BMI) are associated with genetic makeup. But genes haven’t changed in the past 50 years, so differences between individuals don’t explain trends....The clearest change concerns food availability and cost. Since the 1970s, there has been a significant drop in the share of income spent on food—yet each food dollar buys a lot more....As the obesity epidemic has grown and food prices relative to income have dropped, Americans have been eating more of everything, including fruits and vegetables. In terms of macronutrients, most extra calories come from carbohydrates. U.S. markets have succeeded in largely solving the age-old problem of food scarcity, so the answer isn’t to return to higher food prices across the board. But with the solution to food scarcity contributing to a new threat, Americans need market forces to shift them in a different direction and help stem the obesity epidemic....Under the influence of conventional wisdom, many policy interventions focus on “positive” messages: Eat more fruit and vegetables. Get more exercise. However, given that fruit and vegetable availability and physical activity have both increased while relative food prices have plummeted and obesity rates have soared, reducing discretionary calorie consumption may be a more promising lever to reduce overweight and obesity.
So here is the most important message regarding control of obesity: reduce calorie consumption. This approach is sometimes referred to as portion control (see: Portion control key to fighting obesity, expert says). There are some tricks to this approach to weight reduction such as using smaller plates and avoiding "all you can eat" food buffets. In the final analysis, however, reducing the amount of food eaten requires self-discipline. This is difficult because companies that manufacture various types of foods load them up with the salt, sugar, and fat that we like very much (see: Some Salty Facts Keeping to a Healthy Diet; The Harmful Health Effects of Sugar; Next Steps?). I have been told that the theory behind diet programs such as Jenny Craig is portion control. Here's an article about how to learn portion control using the Jenny Craig prepared foods (see: How to Learn Portion Size With Jenny Craig). Learning portion control can be tough in this country, particularly if you commonly eat in fast food restaurants where there are lots of incentives to "super-size" your meal.