Obesity in 2018: Do we have an epidemic, and if so what caused it?
DOI:
https://doi.org/10.14288/hfjc.v11i2.248Keywords:
Adiposity, Body mass, Diet, Physical activity. Secular changeAbstract
Objective. To document the existence, nature and course of the "obesity epidemic," and to explore secular correlates that appear to have played a part in its causation. Methods. Analysis of relevant literature through the data bases of PUBMED and Google Scholar to March 2018, supplemented by material held in the author's personal files. Results. There is good evidence of an epidemic in the sense that obesity has become widely prevalent in many countries over the past 3 decades; in particular there has been an increase in the proportion of grossly obese individuals. Obesity showed its first increase in North America and Western Europe, but the epidemic has spread progressively to developing countries, with the increased prevalence of obesity being seen first in urban areas. In western countries, the proportion of obese individuals rose markedly in the 1980s, and now appears to be reaching a plateau, although from the viewpoint of health, the obese fraction of the population remains undesirably large. Commonly supposed causes of the epidemic include secular changes in the amount and type of food ingested, and a progressive decrease of habitual physical activity, but there could also be influences from a wide variety of other social and environmental changes, some of which match the obesity epidemic in terms of their timing. Discrimination among these potential causes remains important to the design of appropriate tactics to combat the epidemic. Conclusions. Weight for height ratios and skin-fold thicknesses have increased substantially in many countries over the past 2-3 decades, and an associated decrease of lean tissue has masked the full extent of an adverse secular change in body composition. A decrease of habitual physical activity, an increased intake of sucrose and associated over-eating are likely primary causes, but a multitude of other demographic, social and environmental changes could also have played a contributory role. A clarification of causation remains difficult because of the small magnitude of the daily energy imbalance leading to obesity, but nevertheless a determination of aetiology remains important to the design of appropriate future preventive efforts.
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