A recent publication by Flórez, et al, in the Journal of the American Medical Association (JAMA) points out the influence of migration to the US over increased prevalence of obesity among first and second generation Mexican Americans, and describes the typical US diet as “obesogenic.” I agree with this conclusion, which highlights the relative greater importance of external factors (environment) over internal factors (genes) in determining body weight composition. However I would go a step further and characterize Western lifestyle as “obesogenic,” due to a triad of excessive caloric intake, sedentary life, and high levels of stress. Excess weight and obesity affect not only people in the US, but also have become a global epidemic, particularly in urban populations. The significance of this phenomenon lies in the fact that excess weight and obesity are preventable risk factors for the main causes of disease and death in the world, including type II diabetes, heart disease and stroke, as well as some forms of cancer. In order to confront this worldwide epidemic, comprehensive approaches need to be developed urgently, focusing on prevention, particularly in children, since once established, being overweight and obesity are extremely complex to resolve.
The study by Flórez, et al, is one in a multitude of migration studies that have been performed in order to assess the relative importance of environmental vs. genetic factors on the development of obesity and its associated chronic diseases. Starting with landmark descriptions by Marmot, et al, in 1975 regarding migration of Japanese individuals to Hawaii and California, where a gradient of increased risk of obesity and its related chronic diseases was observed; the closer to the continental US, the higher the risk. Pointing at a higher influence of the environment over that of genetic factors. Many studies, in all continents, have reported similar increases in body weight and other cardiovascular risk factors such as high blood pressure and cholesterol levels, associated with migration, particularly from rural to urban settings and also from less developed to more developed countries. It makes sense to describe Western lifestyle as “obesogenic”, given the relative ease of access to ever increasing amounts of high calorie, highly addictive (sugar, salt), processed foods, devoid of nutrients, coupled to a sedentary lifestyle, where most people spend the majority of their work-hours behind desks, commute to work by car and depend on passive electronic entertainment. Both factors, compounded by rising stress levels and widespread prevalence of depression and anxiety, which can potentially worsen the diet-physical activity balance in the form of negative coping mechanisms. Obesity and its associated co-morbidities become more prevalent, the farther away from agrarian, physical-labor-intensive societies.
As an example, if levels of physical activity remain constant, it only takes an extra ½ a cookie a day, as an excess caloric intake, to gain one pound of body weight in one year. That does not sound like much, but it exemplifies what has happened to the average American adult over the past few decades. The excess of one pound of body weight gain per year, if sustained, translates into gaining 10 pounds of body weight in a decade, and 40 pounds between ages of 20 and 60. For an average woman, 160cm tall and weighing 60kg (132lb,) which would be a healthy weight at age 20, such amount of weight gain would turn her into an obese woman at age 60, weighing 172 pounds. This is probably also happening now around the globe.
Available data point to very significant increases in global overweight and obesity rates over the past two to three decades. Currently in the US, 2 out of every 3 individuals are either overweight or obese, therefore, first and second generation Mexican Americans are not the only population group affected by the obesity epidemic. There are other immigrant groups, as well as the US born population, though there are differences in prevalence depending on socioeconomic status and ethnicity. It is currently estimated by the World Heath Organization (WHO) that nearly 1.5 billion adults worldwide are overweight or obese. Even among children, overweight and obesity rates are increasing. It is estimated that over 43 million children under age 5 are obese and 92 million are at risk of overweight. The rise in overweight and obesity rates has already led to increases in diabetes and related chronic illnesses, constituting an important burden to rising healthcare costs. According to WHO estimates, 347 million people worldwide have diabetes and about 3.4 million people die from it every year. The yearly death toll of diabetes is expected to increase by two thirds by the year 2030. Many of the developing countries are also victims of the Western lifestyle, particularly in urban areas, which also are witnessing increasing rates of obesity and related diseases. What is known as the “epidemiological transition”, where people still suffer from infectious diseases and under-nutrition, problems that have been mostly overcome in developed countries, but at the same time, are victims to the diseases of affluence, as they were once known. Many schools in developing countries have students who are either under-nourished or obese in the same classroom; this results in significant challenges for the implementation of appropriate public health policies.
This is a global public health crisis and urgent action in prevention is required. There is a pressing need to develop healthy environments for children and their families, to increase access to healthy food and physical activity, and to provide the skills to successfully navigate the “obesogenic” postindustrial lifestyle. Schools can play a vital role in this challenge, by developing comprehensive curricula and interventions focused on prevention. A healthy body and mind are essential for the development of a happy and productive society.
Resource: Mexico–United States Migration and the Prevalence of Obesity: A Transnational Perspective. Karen R. Flórez, DrPH, MPH; Tamara Dubowitz, ScD; Naomi Saito, MS; Guilherme Borges, PhD; Joshua Breslau, PhD. Arch Intern Med . 2012;172(22):1760-1762. doi:10.1001/2013.jamainternmed.77.
Resource: Marmot, M.G., Syme, S.L., Kagan, A., Kato, H., Cohen, J.B., and Belsky, J., 1975. Epidemiologic studies of coronary heart disease and stroke in Japanese men living in Japan, Hawaii and California: prevalence of coronary and hypertensive heart disease and associated risk factors. Am Journal of Epi. 102 (6), 514-524.
Dr. Chiriboga obtained his postgraduate training in Preventive Medicine at the University of Massachusetts Medical School and School of Public Health. He designed and implemented a comprehensive healthcare system for the indigenous people in central Ecuador 1988-2001. He served as Minister of Health in Ecuador (2010-11) where he undertook a major re-structure of the healthcare system of the country. He also served as President of the Health Council for the Union of South American Nations (UNASUR) 2010, bringing key draft resolutions regarding generic medicines and research and development of medicines for neglected diseases, and a proposal for the need to re-structure the World Health Organization, which were approved by the World Health Assembly. Dr. Chiriboga was the keynote speaker for the European Union Conference in Global Health held in Brussels in 2010. His interests include global health equity, the development of affordable universal health care systems, as well as multisectorial prevention strategies.
Dr. Chiriboga was one of many speakers at Wheelock College’s International Conference .