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 Obesity

september 2012

Obesity Weighs Heavily On Your Brain

Dr Sudhir Kumar 
 
The brain or the central nervous system has signals to ‘stimulate’ food intake as well as to ‘inhibit” it, but the dominant signals are the stimulatory ones.

Overweight and obesity are amongst the major public health issues of our day. Obesity for that matter is now referred to in epidemic parlance. It is the major risk factor for brain stroke, heart attack and cancer, the three leading causes of death in the world. India too has sufficient cause for alarm. According to the National Family Health Survey (2007), 16 per cent of Indian women and 12 per cent of Indian men are obese. Needless to say, it is important to understand the issues leading to obesity, to better address the management and treatment of obesity.

Neurological Aspects Of Obesity
The reasons for becoming obese are often oversimplified and cited as ‘higher intake of food’ or ‘burning fewer calories’. However, there are complex reasons behind it them. The centres for ‘satiety’ and ‘hunger’ are both located in the brain, implying that our urge to ‘eat’ or ‘not to eat’ is also controlled by the brain! No doubt, that the taste and aroma of the food in question dictates our initial urge to gorge, but the continued urge to overeat is controlled by signals from the brain. The brain or the central nervous system has signals to ‘stimulate’ food intake as well as to ‘inhibit’ it. The dominant signals are the stimulatory ones. That people tend to over eat chocolates and ice creams in a party or that most people always have enough space for desserts even after having a wholesome meal should prove it, sufficiently, for us.

The other aspect regarding brain and obesity is the link between stress and overeating. It has been noted that people with chronic stress and some forms of depression tend to overeat over long periods leading to obesity.

Obesity also has some adverse effects on brain. It has been found that obese people tend to have poorer memory and poorer cognitive functions, as compared to those with normal weight.

Also, obese individuals tend to remain isolated and are often made fun of in their peer group, leading to anxiety and behavioural problems.


Weight Regulating Mechanism
The regulation of body weight is coordinated by the interplay betweena food intake and energy expenditure. Leptin, the hormone secreted by adipocytes is the key regulator of both of these processes. Indeed, mutations in the genes encoding leptin and its cognate receptor cause severe obesity. Leptin’s actions are mediated principally by target neurons in the hypothalamus, where it acts to alter food intake, energy expenditure, and neuroendocrine-function. Recently, it has also become clear that a number of critical neuropeptides are regulated by leptin in the hypothalamus.

Weight Loss Treatments/ Medications: Pros & Cons
The growing awareness on the importance and obvious benefits of maintaining a healthy weight has also made weight loss treatments very popular. The cause for concern, however, is a certain misguided penchant of even those with normal body weight to take to rigorous weight loss programmes. The younger generation in particular is prone to this measure. Weight loss treatments can be hazardous or affect adversely too and a person has to be cautious and well-guided before embarking on one. Consult a doctor, always.

Crash diets are the commonest method employed to lose weight and they are typically low in carbohydrates. Some are even deficient in essential vitamins and nutrients. Diets rich in fat and low in cholesterol may lead to certain diseases in later life. Heart disease, high cholesterol, kidney problems and cancer are some to mention.

Weight loss pills are the other common method of reducing weight in the obese. Some points to be noted are:
  • Weight loss drugs have only been tested in obese people and not overweight people. So, these pills may not work in those who are overweight by say just 20-25 kg. Moreover, they may have side effects.
  • They have not yet been tested for long-term, so their efficacy beyond 1-2 years is unknown.
  • One weight reduction pill - fenfluramine/phentermine - was withdrawn from the market, after it was found to cause heart valve problems.
  • When you stop or get off the pills, a part or whole of the lost weight may be regained.
Indian Scenario
Obesity is a major factor that has led to an increase in the prevalence of type II diabetes, heart attack and brain stroke in India. Diet management and exercise remain the best methods to control body weight. Anti-obesity pills are not yet available in India. Moreover, they are costly (Rs 6,000-12,000 per month).

Drugs Approved For Treating Obesity
After what was a gap of 13 years, in the US, its FDA recently approved two drugs for treating obesity [Belviq - locaserin hydrochloride and Qsymia - a combination of phentermine and topiramate]. But these drugs too have not been tested in overweight people but the obese only. Regular counselling and exercise were part of the clinical trials to test them. Adverse effects that were noticed during the period were attention and memory problems and low sugar in diabetics (Belviq); increase in heart rate, tingling of hands and feet and increased risk of foetal malformations (Qsymia).

Therefore, anti-obesity pills should only be taken under strict medical supervision.

Dr Sudhir Kumar is Senior Consultant Neurologist, Apollo Health City, Hyderabad.