The survival of animal species requires continuous supply of energy for physiological functioning, even though the supply of food is intermittent.
This requirement of food has been met by the evolution of a mechanism for storing energy in fuels, mainly the tri-glycerides of fat, from which it can be metabolized.
The mechanism is controlled by the so-called thrifty genes, was an obvious asset to our ancestors. However, in this present affluent society that combines sedentary lifestyles with an ample supply of calorie rich foods. This is the cause of an increasing medical problem - OBESITY.
Obesity is a growing health problem in many of the richest nation of the world and should now be considered as a chronic disease that is reaching / taking a form of epidemic.
Previous thought was that the body had a homeostatic system for controlling body fat and central nervous system (CNS) was involved.
At the beginning of the 20th century that patients with damage of hypothalamus tended to get fat. In the 1940s, it was shown the discrete lesion in the hypothalamus of rodents caused them to become obese.
IN 1953, Kennedy proposed on the basis of experiments of rats that suggested homeostatic mechanism did in fact exist and that is involved a hormone from the adipose tissue acting on the hypothalamus. The details of this phenomenon is now becoming clear, and is leading to an understanding of the problem of obesity.
What does exactly OBESITY mean?
Obesity has been variously defined as an "excess of body fat" or "body weight" that is 20% over the ideal. This phrases "excess" and "ideal" left us with the problem of defining obesity exactly.
The nutritionist achieved more precision: Body Mass Index (BMI). The BMI is body mass (kg) divided by the square of the height (meters). It is highly co related with body fat. The healthy people have BMI of 20-25, those with a BMI of 25-30 are deemed to be over weight and those with, BMI more than 30 are said to be OBESE and those with more than 40 BMI are said to be Morbidly Obese.
The level of BMI obviously depends on the energy balance and operational definition of obesity would be that, it is a multi factorial disorder of energy balance in which, calorie intake over the long term has been greater than the energy output, resulting in excessively large BMI.
Pharmacological Approaches to Obesity:
- Carefully controlled diet and physical exercise are the main therapeutic approaches towards obesity
- But increasing number of patients may also need anti obesity drugs whose aim is to suppress food intake, increase expenditure or increase break down of stored fat (lipolysis)
- At present only two drugs have been shown to reduce the body weight of obese individual:
- ORLISTAT-which decreases fat absorption by preventing the breakdown of dietary fat in GIT and
- Sibutramine - It acts as an inhibitor at CNS sites that stimulates food intake
- Neither is ideal as most Orlistat is excreted through faeces and only minute amounts being absorbed with adverse effects like abdominal cramp, faecal incontinence can occur but surprisingly the drug is well tolerated but supplementary therapy with fat-soluble vitamins may be needed
- Sibutramin originally intended to be used as an antidepressant, as recently been shown to have anti obesity action also. It acts by inhibiting of neuronal 5HT (hydroxyl tryptamine) / noradrenaline reuptake at hypothalamic sites that regulate food intake but with adverse drug reaction reported as increase in heart rate, hypertension and contraindicated if cardiovascular disorder is present.
So, why not take a safer side to fight obesity? Those people who are tending to obese, why not to follow the proverb: Prevention is better that cure and those people who are already obesed or morbidly obesed be alert and are advised to take the given advise and maintaining it continuously which will surely lead you towards the path of healthy life, after all Health is Wealth
Learn vital mechanism of obesity & related factors
The homeostatic mechanism of controlling energy balance:
The energy balance depends on food intake and storage of energy in body fat and energy expenditure. The regulation of energy balance requires:
- A mechanism for sensing the level of energy stored in the body fat and relaying the information to control sites of hypothalamus.
- Secondly, the integration of the information in hypothalamus and thus determining the energy balance through control of food intake and energy expenditure
- It involves many interacting factors - endocrine, autonomic mediators, GIT Peptides, CNS Transmitters etc. All these impinging on the hypothalamus that in turn releases mediators that acts on CNS, autonomic and endocrine system. This then affects food intake and energy balance.
For many years it had been known that mice can become Obese as proposed by Kennedy in 1953 through mutation of certain genes. At least five of which have been identified, including ob obesity) genes, db (diabetes) genes, agouti yellow, tubby and fat. This version of genes occurs in humans also.
