What is Obesity?
Obesity is defined as an abnormal or excessive accumulation of fat that may impair health.
Obesity is one of the leading causes of preventable death worldwide (and second only to smoking in the United States). It is also associated with increased risk of serious health conditions such as certain forms of cancers, type 2 diabetes, chronic heart disease, high blood pressure, stroke, respiratory disorders, heartburn, infertility, as well as psychological and social problems.
Causes of Obesity
Obesity develops in an individual when energy intake exceeds energy expenditure over a prolonged period and the excess is stored as fat due to this imbalance.
Inherited causes of obesity are extremely rare, but there may be susceptibility genes on which environmental factors act on to cause obesity. A complex interplay of genetic and environmental factors thus determines the age of onset and the severity of obesity.
There are a number of adverse environmental influences that play an important part in the development of obesity in an at-risk individual. The most common factors include:
- Unhealthy diet and eating habits
- Sedentary/inactive lifestyle
- Irregular sleeping pattern/lack of sleep
- Cessation of smoking
Other risk factors for obesity are:
- Advancing age
- Past pregnancy and menopause
- Polycystic ovarian syndrome
- Medications such as steroids, antidepressants, anti-seizure and diabetic drugs
- Hypothyroidism (rare)
Complications of Obesity
It is important to recognise that obesity is associated with a multitude of serious medical problems that contribute to reduced quality of life and are potentially life-threatening.
The causal relationships are often complex with:
- Medical problems causing obesity and obesity causing medical problems
- Environmental factors (such as sedentary lifestyle or poor diet) causing both the medical problem and obesity
The list of chronic health conditions is broad and include:
- Type 2 diabetes
- Heart disease
- High blood pressure
- Snoring and obstruction to breathing when sleeping (Obstructive sleep apnoea)
- Heartburn (“Reflux” disease)
- Fatty liver disease and cirrhosis
- Gallstone disease
- High cholesterol level
- Chronic kidney disease
- Joint problems (Osteoarthritis)
- Erectile dysfunction
- Lost of bladder control (urinary incontinence)
- Blood clots in deep leg veins and in lungs
- High pressures in brain fluid
There are also a number of cancers that are found to be strongly associated with obesity such as:
Diagnosis of Obesity
Clinical diagnosis of obesity is based on calculation of Body Mass Index (BMI) using weight and height measurements. Any person with BMI between 25 and 29.9 is termed overweight and any individual with BMI of 30 or more is classified as obese (see table below). Based on the BMI, obesity is divided into class I, II and III and risk of medical problems increases from classes I to III.
Check your BMI
Treatment of Obesity
The goal of treatment is to increase life expectancy through weight loss and to cure/lower the risk of obesity-related health conditions while improving psychological well-being and social function.
It is widely acknowledged that achieving and maintaining weight loss can be difficult. Conservative treatment through dieting, lifestyle modifications and medical therapy has a high failure rate. Weight loss (Bariatric) surgery has been shown to be the most effective method in sustained weight reduction with the potential to cure or to reduce obesity associated medical conditions.
However, overeating and low physical activity are still the fundamental problems underlying the development of obesity. Thus any surgery aimed at treating obesity must have a dietary and physical activity component to the overall management of this difficult health problem.
It should also be noted that weight loss treatment is time consuming and requires a life-long commitment to maintaining dietary discipline and adequate physical activity. Therefore surgery is generally recommended to individuals who are at the most risk (morbidly obese) and are motivated. Using certain behavioural techniques and helping to identify barriers to change and providing the tools to overcome them will improve the likelihood of successful weight loss and maintenance of this.
Surgery for Obesity
Weight-loss surgery, also known as bariatric surgery, is considered only in patients with severe obesity (BMI of 40 and over, or BMI of 30-39.9 in those with obesity-related health conditions). Depending on the choice of operation, weight loss surgery causes weight reduction in a number of ways which include:
- limiting the amount of food stored in the stomach
- limiting absorption of food
- causing hormonal changes that are produced by your gut (which reduces hunger and affects the body’s metabolism)
The available surgical options for weight-loss include:
- Gastric sleeve, also called tube gastrectomy, involves in reducing the size of the stomach by stapling and removing a large part (75%) of the stomach. After this procedure the remaining stomach becomes tube-shaped rather than a pouch and thereby limiting the amount of food that can be stored in the stomach.
- Gastric bypass surgery, also called Roux-en-Y gastric bypass, involves in creating a small pouch at the top of the stomach and bypassing the flow of food away from the first part of the small intestine and directly to the middle part of the small intestine. The weight loss effect is primarily achieved through limiting the amount of food stored in the small pouch and the hormonal changes that occur through diverting food away from the first part of the small bowel. There is also a small limiting effect on the absorption of food.
- Adjustable gastric banding or lap band surgery involves in placement of an adjustable band near the top of the stomach. The food intake is restricted or limited by the constricting outlet effect of the adjustable band. This procedure causes weight-loss by reducing the functioning capacity of the stomach.
* All of the above surgical options are performed laparoscopically (key-hole surgery)