Obesity, especially "central", "visceral", "truncal", "android" (i.e. abdominal) is a major (AHA/NHLBI) or sine qua non (IDF) criteria for the diagnosis of the Metabolic Syndrome. Whilst its presence is an absolute requirement for the diagnosis of the metabolic syndrome as per the IDF guidelines, it is only one out of five criteria, the presence of any three of which leads to a diagnosis of the metabolic syndrome as per the modified ATP-III guidelines.

Atherosclerosis is now considered in part to be a consequence of chronic low-grade inflammation and this is also considered to play an important role in leading to T2DM.

Visceral adiposity leads to an increase in the proinflammatory and prothrombotic state. It leads to an exacerbation of insulin resistance and drives the progression of multiple cardiometabolic risk factors independently of body mass index.

For a list of the Metabolic and Cardiovascular Risk Factors Associated With Visceral Obesity, see Appendix 15a.

At the same time, generalized obesity is also associated with many other disorders and increases to the morbidity as well as even mortality associated with these disorders. Thus, the management strategy has to be a decrease in all obesity, but special attention must be paid to reducing the abdominal obesity.

Generalised obesity is best measured by estimation of the Body Mass Index (BMI)

Body Mass Index (BMI)

                     Weight in Kg
BMI = -------------------------
                 Height in meters2

Normal: 20-23; > 23-25 = Overweight; > 25 = Obese (for people from the Indian subcontinent)

Care must be taken that the weight is not decreased below the lower limits, as a BMI of 18.5 signifies low body weight.

For BMI charts, see Appendix 2a

Central or visceral obesity is best measured by the waist circumference.

For the method to measure the waist circumference and also the national/ethnic specific waist measures see Appendix 1c.

Goals

The management strategy has to be a decrease in all obesity, but special attention must be paid to reducing the abdominal or visceral obesity.

Lifestyle Management

Effective weight loss requires a combination of caloric restriction, physical activity, and motivation; effective lifelong maintenance of weight loss essentially requires a balance between caloric intake and physical activity.

Aim initially at slow reduction of 7% to 10% from baseline weight. Even small amounts of weight loss are associated with significant health benefits. Continue weight loss thereafter to extent possible with goal to ultimately achieve desirable weight.

Weight loss at the rate of 1 to 2 lb/week (calorie deficit of 500 to 1,000 kcal/day) commonly occurs for up to 6 months.

After 6 months, the rate of weight loss usually declines and weight plateaus because of a lesser energy expenditure at the lower weight and the lifestyle prescription may need to be revised.

Experience reveals that lost weight usually will be regained unless a weight maintenance program consisting of dietary therapy, physical activity, and behavior therapy is continued indefinitely.

Many of these aspects have been discussed in detail in the section dealing with diet therapy.

Increased physical activity along with regular exercise is recommended as an important component of all lifestyle management regimens to prevent and manage the metabolic syndrome as well as all diabetes management regimen.

Increasing physical activity assists in weight reduction, reduces insulin resistance, has beneficial effects on metabolic risk factors; and importantly, it reduces overall ASCVD risk beyond that provided by weight reduction alone.

Many of these aspects have been discussed in detail in the section dealing with exercise therapy.

Pharmacotherapy

Lifestyle therapy should be considered before drug therapy and should be continued during the pharmacotherapy.

Weight loss drugs may be used as part of a comprehensive weight loss program for patients with a significantly raised BMI or significantly increased waist circumference.

Avoid use of drugs without accompanying lifestyle modification.

Avoid medications which are known to be associated with weight gain.

For a partial list of medications which have weight gain as a side effect see Appendix 15b.

The two drugs which are presently available and most commonly used weight reducers are Orlistat and Sibutramine.

Characteristics of the Commonly used Antiobesity Medications

Metformin was used in the past as a weight reducing agent even in people with normal glucose levels. But its use has decreased with the availability of sibutramine and orlistat.

With the increasing awareness of the critical role played by insulin resistance, which leads to many disorders such as Polycystic Ovary Syndrome (PCOS), etc., as well as being a serious risk factor for diabetes and premature cardiovascular disease, its use especially in patients with impaired glucose tolerance, and this is especially so in patients with a family history of diabetes and premature cardiovascular disease.

Many trials have shown that a 20 mg dose of rimonabant, which is used in the management of obese diabetics, can lead to an average weight loss of approximately 6 kg over a year when accompanied with lifestyle therapies. Importantly, it leads to a decrease in abdominal obesity and improves cardiovascular risk factors. The most common reported side effects include depression, anxiety, and nausea and should not be used in patients on anti-depressives. It is NOT accepted for use by the U.S. FDA.

GLP-1 analogues have been shown to be associated with weight loss, although the DPP-IV inhibitors are weight neutral.

The glitazones tend to increase the weight. But it is now being increasingly realized that whilst the glitazones may slightly increase the fat levels in the body, they very significantly decrease the levels of central or visceral obesity. At the same time questions have been raised about the cardiovascular safety of rosiglitazone and it remains to be seen whether this is a class effect and applies to pioglitazone as well.

Other drugs including sympathomimetics are now rarely used.

Although some other drugs such as bupropion and topiramate are being "pushed" as agents to use in obesity, but are not widely accepted as antiobesity drugs.

Phentermine by itself continues to be occasionally used.

Drugs such as fenfluramine, ephedra and phenylpropanolamine should NEVER be used. One has to be very careful as many OTC drugs and herbal products contain them or similar agents and can be dangerous in the long term.

Weight loss surgery is an option in carefully selected patients with clinically severe obesity with comorbid conditions when less invasive methods have failed and the patient is at high risk for obesity-related morbidity and mortality.