Defining Obesity

 

Obesity is no longer considered a cosmetic issue that is caused by overeating and a lack of self-control. The World Health Organization along with National and International medical and scientific societies, now recognize obesity as a chronic progressive disease resulting from multiple environmental and genetic factors.

 

The disease of obesity is extremely costly not only in terms of economics, but also in terms of individual and societal health, longevity, and psychological well-being. Due to its progressive nature, obesity requires life-long treatment and control.

 

Measuring Obesity

 

Body Mass Index (BMI)

 

  • BMI is used to define overweight and obesity.

  • Large population studies find that the BMI generally reflects the amount of excessive body fat an adult has, although there are certain exceptions, such as the BMI of a woman who is pregnant, an athlete, a body builder or the elderly.

 

  • BMI takes into consideration an individual’s height and weight. It can be calculated according to the following formula:

 

​Weight in kilograms divided by Height in meters squared (BMI = kg/m2)

 

For example, if you weight 75kg and you are 175cm tall (1.75m), your BMI = 75 / (1.75 x 1.75) = 24.5

 

  • Body size categories are based upon the ranges of BMI associated with a certain risk for mortality. 

 

Obesity Prevalence and Rate of Occurrence

 

  • Approximately 500 million adults in the world are affected by obesity and one billion are affected by overweight, along with 48 million children.

 

  • In Australia, 63% of adults are overweight or obese.

  • 1 in 4 children are overweight or obese

  • Obesity is the 2nd highest contributor to burden of disease, after dietary risks. Smoking is the third highest.

 

Progressive Nature of the Disease of Obesity

 

Obesity is considered a multifactorial disease with a strong genetic component. Acting upon a genetic background are a number of hormonal, metabolic, psychological, cultural and behavioral factors that promote fat accumulation and weight gain.

 

Positive Energy Balance

 

A positive energy balance causes weight gain and occurs when the amount of calories consumed (energy intake) exceeds the amount of calories the body uses (energy expenditure) in the performance of basic biological functions, daily activities, and exercise.

 

A positive energy balance may be caused by overeating or by not getting enough physical activity. However, there are other conditions that affect energy balance and fat accumulation that do not involve excessive eating or sedentary behavior. These include:

 

  1. Chronic sleep loss

  2. Consumption of foods that, independent of caloric content, cause metabolic/hormonal changes that may increase body fat. These include foods high in sugar or high fructose corn syrup, processed grains, fat, and processed meats

  3. Low intake of fat-fighting foods such as fruits, vegetables, legumes, nuts, seeds, quality protein

  4. Stress and psychological distress

  5. Many types of medications

  6. Various pollutants

 

Weight Gain

 

  • Weight gain changes the biology of the body that  favours further weight gain and obesity. 

  • These obesity-related biology changes reduce the body's ability to burn fat and increase the conversion of glucose (carbohydrate) to fat. They also increase the body's capacity to store more fat. 

  • To make matters worse, obesity affects certain regulators of appetite and hunger, which lead to increase in meal size and the frequency of eating. 

 

Obesity-related Conditions

 

  • Obesity reduces mobility and the number of calories that would be burned in the performance of activity.

  • Weight gain may also cause psychological or emotional distress which, in turn, produces hormonal changes that may cause further weight gain by stimulating appetite and by increasing fat uptake into fat storage depots.

  • Sleep duration is reduced by weight gain due to a number of conditions that impair sleep quality such as pain, sleep apnea and other breathing problems, a need to urinate more frequently, use of certain medications, and altered regulation of body temperature. Shortened sleep duration, in turn, produces certain hormones that both stimulate appetite and increase the uptake of fat into fat storage depots.

  • Weight gain also contributes to the development of other diseases such as hypertension, diabetes, heart disease, osteoarthritis and depression, and these conditions are often treated with medications that contribute to even further weight gain. 

  • In all of these ways and more, obesity ’begets’ obesity, trapping the individual in a vicious weight gain cycle.

 

Diets

 

  • A low calorie diet is the primary treatment for overweight and obesity, but, dieting is also a contributor to obesity progression.

  • Dietary weight-loss causes biological responses that persist long-term and contribute to weight regain.

  • One of these responses affects energy balance. When a person loses weight, the body ‘thinks’ it is starving and energy expenditure is reduced in order to conserve calories. The reduction in energy expenditure requires that, in order to maintain weight-loss, the dieter eat even fewer calories than someone of equal body size who has never been on a diet. However, eating less is difficult following a diet because there are long-term changes in regulators of appetite that increase the desire to eat and the amount of food that can be consumed. Such diet-induced changes favor a positive energy balance and weight regain and, because the conditions responsible for the reduction in energy expenditure and increased drive to eat persist long-term, an individual will often not only regain all of their lost weight, but even more.

  • Another biological response that occurs with dieting involves changes in fat metabolism that reduce the body’s ability to burn fat and increase the capacity for fat to be stored in fat storage depots.

  • With dietary weight-loss, the amount of dietary fat the body burns is reduced by approximately 50 percent. In addition, dieting reduces the amount of fat the body burns for fuel during low-grade activity such as walking, cleaning the house, fixing dinner, or working on a computer. The reduction in the amount of fat that is burned for fuel following a dietary weight-loss makes more fat available to be taken up by fat storage depots, and dieting increases the capacity for fat depots to store even more fat than before a diet.

  • Altogether dietary weight-loss reduces the use of fat for fuel and increases the capacity for the fat that is not utilized to be stored. These changes lead to a progressive increase in fat accumulation even if the individual is not overeating.

 

 

Summary

 

  • Multiple factors acting upon a genetic background cause weight gain and obesity.

  • Conditions associated with weight gain and biological changes in the body that occur as a result of weight gain contribute to progression of the disease, often trapping the individual in a vicious weight gain cycle.

  • If you are concerned with your weight, please speak to your family physician to learn more about how to improve your weight and health. For surgical solutions, you are welcome to leave comments and ask questions here, or make contacts with us. 

 

Dr. Yuan Cheng @ 2020