Fat lot of good

Bariatric or gastric binding surgery,which drastically cuts down the amount of food a person can consume has gained popularity as an effective weight-loss measure and the scientific community hopes to make an obesity vaccine too.

According to recently released WHO statistics,11 per cent of India’s population is overweight and nearly 24 million people (2 per cent of population) are obese.

In the last five years,two so-called obesity panaceas have been banned in India. There is only one approved anti-obesity drug in India,which is only mildly effective.

Doctors often vouch for the safety of orlistat,which has been available in the market for around 10 years,even though it is known to cause diarrhoea at times. It is effective on only 20 per cent of patients,those who have a high fat intake. It is a prescription drug,just like lorcaserin (the newly-approved drug). Drugs approved in the US normally take a year or two to reach Indian chemist shops.

Lorcaserin has been approved for healthy adults with a body mass index (BMI) of 30 or above. Those with a BMI of 27 and one obesity related health condition (like hypertension) can also be prescribed the drug. The drug acts on brain receptors associated with satiety. So,a person who takes the drug would feel satiated with less amounts of food.

BMI is a measure of the fatness of a person,a ratio of body weight and the square of height in the same measurement system.

“Any anti-obesity drug is welcome,but given the dismal history of anti-obesity drugs,I am not enthusiastic about these. I may still use it for want of anything better,but not too frequently,” says Dr Amrish Mithal,chairman and head of the department of endocrinology and diabetes at Medanta Medicity.

The real deal,according to Dr S K Wangnoo,consultant endocrinologist at Indraprastha Apollo,would be a drug that converts inert white fat to the metabolically active brown fat. Lorcaserin can lead to weight loss of up to 15 per cent in a year,which is what most such drugs can achieve. So there is little reason to expect miracles from the new anti-obesity drug,he says.

Dr Wangnoo’s prescription of an ideal obesity drug is one that takes care of the basal metabolic rate (BMR) issues associated with obesity. BMR is the amount of energy expended by the body of a healthy person per hour per square metre of body surface 10-12 hours after a meal,while in a state of complete mental and physical rest but not sleep. BMR is often believed to be lower for obese people because of the presence of excess metabolically inert fat cells that add mass but do not spend energy. This,coupled with the excess intake of food,causes further weight gain,and low BMR is not always offset by higher body mass and its associated increase in BMR.

It is an accepted fact that anti-obesity drugs are tricky business. In the 1990s,an anti-obesity drug combining fenfluramine and phentermine — popularly known as fen-phen — is known to have invited around 50,000 product liability lawsuits amounting to claims of $14 billion. Fen-phen was associated with pulmonary hypertension and heart valve problems,and was withdrawn later.

What is it about anti-obesity drugs that makes them so difficult to get right? They attempt to suppress appetite or activate physiological processes that seem inevitably to lead to cardiac problems. Rimonaband was banned because it caused depression and suicidal tendencies,sibutramine because it caused an increase in heart rate and accentuated the action of the sympathetic nervous system. Companies like Merck have now closed down their research divisions dealing with anti-obesity drugs because of persistent issues related to side-effects,says Dr Anoop Misra,director and head,department of diabetes and metabolic diseases,Fortis Hospital.

The fact that it does not act through either of these two routes could be the secret of the apparent success of orlistat. It acts locally on the intestine to decrease fat absorption but weight loss is only about three to five kg over six months.