By Dr Ananya Mandal, MD
Obesity is a major health problem in today’s world. It has reached epidemic proportions globally. There are over 1 billion adults who are overweight and of these at least 300 million are clinically obese.
Obesity contributes in a major way to the global burden of chronic disease and disability. Obesity in itself is a form of malnutrition that coexists with under-nutrition in developing countries. The condition has serious social and psychological effects and may involve virtually all ages and socioeconomic groups.
Basically obesity is an imbalance between intake and expenditure of energy. It results from intake of more energy-dense, nutrient poor foods with high levels of sugar and saturated fats along with reduced physical activity.
Where are obesity rates increasing?
This has resulted in the massive threefold increase of obesity rates in North America, the United Kingdom, Eastern Europe, the Middle East, the Pacific Islands, Australasia and China since the 1980’s.
As earlier believed, obesity is not restricted to industrialized societies. In fact the number of obese and overweight individuals is rising faster in developing nations than in developed countries.
Obesity and risk of chronic diseases
Obesity and overweight pose a major risk for serious chronic diseases that include:-
Type 2 diabetes
High blood pressure
Gall bladder stones
Fatty liver disease
Some forms of cancers like breast, endometrium (womb) and colon (bowel cancers)
Obesity results in an increased risk of premature death as well as reduction in overall quality of life.
Causes of the obesity epidemic
There are several factors that may be resulting in the rising numbers of obese individuals. In addition to energy intake and expenditure imbalance, hormonal and genetic factors also may result in obesity. Genes are important in determining an individual’s susceptibility to weight gain as well as metabolic rates.
Economic growth, urbanization and globalization of food markets as well as changing norms of food consumption are probably also contributing to the obesity epidemic. Obesity rates have been attributed to increased intake of fast foods as well as increased eating out.
With the rise of economic power foods tend to become high in complex carbohydrates with high percentages of fats, saturated fats and sugars. On the other hand work tends to become less physically demanding giving way to a more sedentary life. Technology and improved transport also contributes to lower physical activity.
Definitions of overweight and obesity
Individuals are considered obese when they weigh more than 20% above their ideal weight. Body mass index (BMI) is calculated as weight in kilograms divided by height in meters squared. The currently accepted criteria for overweight is defined as body mass index (BMI) levels greater than 25 kg/m2 and obesity as BMI of 30 kg/m2.
Another measure is the percentages of body fat. In men minimal fat is 5% while in women it is 8%. Above average body fat in men is between 16 and 25% and among women is between 24 and 32%. Percentage of fat over 25% in men and 32% in women defines risk of disease.
The distribution of fat is one of the major contributors to disease than total body fat. For example, upper body fat distribution is termed Android and has been associated with increased risk of coronary artery disease, high blood pressure, high cholesterol levels, diabetes as well as hormone and menstrual dysfunction.
It is determined by measurement of waist – to – hip ratio. Upper body fat distribution means a waist to hip ratio of over 0.91 in men and 0.86 in women. Lower fat distribution defines low risk and means waist to hip ration of less than 0.78 in men and women.
Risk of disease through fat distribution can also be measured by the waist circumference measurement, measured in centimetres. Low risk individuals have less than 102 cm in males and less than 88 cm in females. High risk means more than these limits.
Reviewed by April Cashin-Garbutt, BA Hons (Cantab)
Last Updated: Apr 8, 2013