A segment of the African population is rapidly adapting to a modernized lifestyle that has resulted in a dramatic rise in the incidence of obesity.
Globally, obesity has reached epidemic proportions as a major public health problem. In developing countries, obesity often coexists with widespread undernutrition, which is a major problem in children under five years old. Undernutrition often leads to conditions such as Kwashiorkor and marasmus due to protein and energy deficiencies, respectively. Obesity, on the other hand, is a major contributor to the global burden of noncommunicable diseases that include type 2 diabetes, coronary heart disease, hypertension, osteoarthritis, fatty liver disease, inflammation, sleep apnea and certain cancers. Obese individuals of all ages also suffer from serious social and psychological consequences.
Obesity in Africa
The precise etiology of the many abnormalities that occur in obesity in the African population still is unknown. Multifactorial causes of obesity include several genetic, dietary and lifestyle variables that together result in an imbalance between energy intake and energy expenditure. It is clear that a segment of the African population is rapidly adapting to a modernized lifestyle characterized by reduced physical activity and increased consumption of processed food rich in carbohydrates and fat, which has resulted in a dramatic rise in the incidence of overweight and obese individuals. Popular foods among children have shifted to those that are more energy-dense, including fast foods, cereals, breads, potato chips and soft drinks.
African diets have a very high carbohydrate component that can dramatically increase endogenous fatty acid synthesis, and since both dietary and endogenously synthesized fatty acids contribute to the whole-body fatty acid pool, obesity can result from excessive fat or carbohydrate consumption. There also is an increasing body of evidence in support of the Barker hypothesis, which proposes that the origins of obesity may actually occur in utero. In particular, links have been established between reduced birth weight and obesity and the associated risk factors in adulthood. The most widely accepted mechanisms thought to underlie these relationships are those of fetal programming by nutritional stimuli. It is suggested that the fetus makes physiological adaptations in response to changes in its environment to prepare itself for postnatal life. These changes may include epigenetic modification of gene expression.
Addressing the epidemic
Little to no attention has been paid to the rising challenge of obesity across the life course in Africans. For instance, much of the data about the extent of obesity in Africa is not published and often is documented in manuscripts in progress or in clinical reports. In addition, there are no well-defined population surveys that have evaluated the linkage of diets to obesity, type 2 diabetes and other symptoms of the metabolic syndrome in Africa. Exacerbating the problem are Africa’s meager financial resources and overstretched skilled human resources, which are unable to combat the new challenges effectively, as well as existing lethal transmittable diseases such as tuberculosis and malaria.
While there obviously are some universal characteristics of the global obesity epidemic, responding to this health problem in each society requires proper understanding of the local environment and factors involved. For example, food availability and accessibility, which have been suggested by studies in North America as important components of the obesogenic environment, do not seem to play a big role in Africa among lower socioeconomic groups. Emphasis must therefore be placed on the preventive aspects of these diseases in order to economize on Africa’s meager resources. Fortunately, many of the chronic noncommunicable diseases listed under the metabolic syndrome are preventable. Both early detection and management of these diseases can help to mitigate costly chronic complications and premature mortality. The challenges are clear, and they also are clearly important.
James M. Ntambi (firstname.lastname@example.org) is the Katherine Berns Von Donk Steenbock professor in the departments of biochemistry and of nutritional sciences at the University of Wisconsin-Madison.