Obesity is the nominal form of obese which comes from the Latin obēsus, which means “stout, fat, or plump.” Ēsus is the past participle of edere (to eat), with ob added to it.
besity is a condition in which the natural energy reserve, stored in the fatty tissues of humans and other mammals, is increased to a point where it is associated with certain health conditions or increased mortality.
Obesity is both an individual clinical condition and is increasingly viewed as a serious public health problem. Excessive body weight has been shown to predispose people to various diseases.
Being obese and being overweight is not exactly the same thing. An obese person has a large amount of extra body fat, not just a few extra pounds. People who are obese are very overweight and at risk for serious health problems.
Obesity is typically evaluated by measuring BMI (Body mass index), waist circumference and risk factor evaluation.
Body mass index is the most simple and useful index to estimate body fat. It is calculated as follows:
BMI = Weight in Kilograms / Square of height in meters.
So BMI = Kg / square ms.
or BMI = Weight (lbs) * 703 / height (inches)2
BMI is indexed as follows for reference:
BMI < 18.5 = Underweight
BMI 18.5 – 24.9 = Normal weight
BMI 25 – 29.9 = Overweight
BMI 30 – 39.9 = Obese
BMI > 40 = Severely obese
With day to day advancements and better understanding, it has become clear that visceral fat or central obesity (male type or apple type obesity) has a stronger relation with cardio-vascular diseases. BMI does not take into account the adipose and lean ratios.
The absolute waist circumference ( > 102 cm in men and > 88 in women) or waist – hip ratio (>0.9 for men and >0.85 for women) are a measure of central obesity.
Body fat measurement
It is considered that men with more then 25% and women with 30% more body fat are obese. For the correct assessment, either skin fold thickness test or under water weighing could be done.
Other measurements could be done by CT or MRI.
Causes of Obesity
When food energy intake exceeds energy expenditure, fat cells (and also to some extent muscle and liver cells) throughout the body take in the energy and store it as fat. So when the energy consumption exceeds the requirement, it causes obesity.
Additional factors causing obesity
- Genetic disorders
- Underlying illness (such as hypothyroidism)
- Eating disorders (such as Binge eating disorder)
- Certain medications (such as anti-psycotics)
- Sedentary lifestyle
- A high glycemic diet
- Insufficient sleep
- Sudden smoking cessation
- Weight cycling – repeated attempts to do dieting to lose weight
Genetic factors play an important role in determining the traits of obesity. Some genes play the role to telling the body how to metabolize food and to use extra calories or stored fat.
Obesity runs in families as generally families eat similar foods, have similar lifestyle habits and thinking patterns, such as that children should eat more to become big and healthy.
Certain illnesses like thyroid gland problems or genetic diseases run in families.
Some eating disorders like Binge eating disorder affect a person’s diet as he eats more and repeatedly often in binges. These people generally lack the developed eating patterns learned in childhood.
It is also to be remembered that obesity is not the result of momentary overeating. It is a long term phenomenon because people tend to overeat over long periods of time.
Emotions can fuel obesity, as people tend to eat more when they are upset, anxious, sad, stressed or even bored. Afterwards they feel bad about eating more, and later to relieve this stress, they may eat even more.
Sedentary lifestyle is another important factor as people tend to eat more when they are doing nothing and just sitting idly watching TV or video games. Cars dominate our life and we seldom walk or exercise. There is less time to cook healthy food and we often tend to eat fast foods.
Since the mid-seventies, the prevalence of being overweight and of obesity in United States have increased sharply for both adults and children. Data from two NHANES surveys show that among adults aged 20–74 years the prevalence of obesity increased from 15.0% (in the 1976–1980 survey) to 32.9% (in the 2003–2004 survey). The global average stands at 14.1% with United States of America, Mexico, United Kingdom, Slovakia, Greece, Australia, New Zealand, Hungary, Luxembourg, Czech Republic standing out as the most obese nations.
The two surveys also show increase in weight among children and teens. For children aged 2–5 years, the prevalence of being overweight increased from 5.0% to 13.9%; for those aged 6–11 years, prevalence increased from 6.5% to 18.8%; and for those aged 12–19 years, prevalence increased from 5.0% to 17.4%.
These increasing rates raise concern because of their implications for Americans’ health. Being overweight or obese increases the risk of many diseases and health conditions, including the following: