What Is Obesity?

Obesity is a medical condition characterized by the accumulation of excess body fat that may result to adverse health effects and lead to reduced life expectancy. A person will know whether he or she is obese by computing his or her body mass index or BMI.

BMI is the measurement of a person’s body shape based on his or her weight and height. You can get your BMI by dividing your weight in kilograms by the square of your height in metres.

A person is considered obese if his or her BMI is greater than 30 kg/m2. He or she is considered pre-obese or overweight if his or her BMI is between 25 kg/m2 and 30 kg/m2.

Most of us are able to maintain a steady weight within a given period despite the amount of energy or food that we consume and without having to maintain a balance between the consumption and the amount of energy we expel through various activities. This ability to control energy balance is called weight homeostasis mechanism.

We all possess this mechanism, which is essential for survival. This mechanism is not just all about keeping weights stable, but mainly about storing fat. This fat storage mechanism came about as a result of evolution, allowing our primitive ancestors to keep any excess food requirement in their bodies in the form of fats – because, come to think of it, they didn’t have refrigerators and they need to have a “stock” of energy during the cold winters and the long hunts.

In other words, all of us are biologically programmed to store a certain amount of fat from day to day. But no two people are exactly the same, so the term “ideal weight” does not really exist. It might differ according to race or ethnic group and other factors.

For a lot of people, being overweight is simply an imbalance between the food or energy one consumes (also known as calorie intake) and the amount of energy expelled through physical activity (also known as calorie burnt). The more one eats, the more fats one keeps stored in his or her body. And weight increases if these excess fats or calories are not burnt off in the same rate energy is consumed. So it is by eating less and engaging in more physical activity or exercise will weight loss will occur.

However, once some people reach a certain size or body weight, changes in their body chemistry also occur, taking away their ability to easily control their energy balance. This also means that they are no longer able to lose excess fats and excess weight by simply eating less and exercising more. These changes are, more often than not, irreversible.

This is why, despite their best efforts, some would just slowly and steadily gain even more weight and eventually reach “obese” levels.

Lifestyle modifications, such as exercise and low-caloric diet, are of limited benefit. Weight loss is about 5% of a person’s initial body weight after one year. Randomised Controlled Trials of a variety of diets showed that final weight loss averaged <5% of initial body weight after two years. This is because the person’s weight homeostasis mechanism has already changed and the chemical changes that occurred in the body make long-term weight loss difficult, sometimes impossible. This process is called “genetic and neurohumoural breakdown in the weight homeostasis mechanism.”

These are important facts about obesity worth noting:

    • It is a global epidemic
    • It is a chronic, relapsing disease, representing a significant and global medical challenge
    • By 2015, 2.3 billion adults will be overweight or will have a BMI of between 25-29 kg/m2
    • By 2015, 700 million adults will be obese or will have a BMI higher than 30 kg/m2
    • In Australia, 60-65% of adults are currently overweight or obese
    • The cost of obesity in Australia is $58.2 billion
    • National Health Surveys suggest that males remain more likely to be overweight than women

There are several definitions for the term obesity. Below is the classification proposed by the World Health Organisation (WHO):

WHO Classification of Obesity BMI kg/m2
Normal 18.5-24.99
Overweight ≥ 25
Pre obese 25-29.99
Obese ≥ 30
Obese class I 30-34.99
Obese class II 35-39.99
Obese class III ≥ 40
Super obese 50.59.99
Super Super obese ≥ 60

*Cut-off may be different for different ethnic groups

Overweight and obese Caucasian adults are at higher risk of metabolic complications relative to the general population if their waist circumference is:

Risk of metabolic complications Waist Circumference (cm)
Men Women
Increased ≥ 94 ≥ 80
Substantially increased ≥ 102 ≥ 98

Once patients are morbidly obese they have an increased risk of early death and have a long list of illnesses that can be attributed to excess fat.

  • Cardiovascular disease (Angina, Heart attack, cardiac failure and stroke)
  • Systemic Hypertension (high blood pressure
  • Accelerated arthrosclerosis
  • Acid reflux (GORD)
  • Musculoskeletal disorders (joint pain, arthritis, osteoarthritis etc)
  • Infertility
  • Polycystic ovarian syndrome
  • Impaired glucose tolerance and type II diabetes
  • Incontinence
  • Depression
  • Dementia
  • DVT and pulmonary embolism
  • Venous stasis leg ulcers
  • Sleep disorders especially obstructive sleep apnoea
  • Raised cholesterol
  • Fatty liver
  • Gall bladder disease (especially gallstones)
  • Skin problems
  • Kidney disease
  • Asthma
  • Some cancers
  • Sexual dysfunction
  • Endometrial hyperplasia and
  • Carcinoma
  • Carcinoma of prostate and colon in males
  • Pseudo tumour cerebri

Of course, that does not include the poor quality of life, psychosocial and economic problems, loss of self-esteem, job discrimination and travel limitations that they have to go through.

The good news is that these illnesses and other problems will either disappear or diminish substantially with fat loss.

So just imagine the satisfaction we get in helping cure people’s weight-related diseases and attain an improved quality of life!