Notions and practical tools to better manage the abdominally obese patient with excess visceral adiposity and related clustering abnormalities.
Targeting Traditional CVD Risk Factors in Patients With Abdominal Obesity
Numerous organizations have published an array of guidelines on managing acknowledged risk factors for cardiovascular disease. Among the management approaches used are treatment of hypertension and dyslipidemia (lowering LDL cholesterol in particular), smoking cessation, and better glycemic control. These measures can produce significant clinical benefits for the patient. This section provides useful links and information to help you better manage these risk factors.
Residual Cardiometabolic Risk of Treated Patients
Numerous clinical trials have shown the benefits of treating traditional risk factors to ward off cardiovascular events. For example, a wealth of lipid lowering trials have demonstrated that lowering LDL cholesterol concentrations with statins reduces the risk of first or recurrent cardiovascular events. However, statin trials that have been able to study subgroups of abdominally obese patients with features of the metabolic syndrome have generally shown the following:
- Patients in statin trials with the metabolic syndrome are more likely to develop cardiovascular complications than patients without the metabolic syndrome.
- Despite the fact that patients with the metabolic syndrome benefit from statin therapy, they are nevertheless at higher residual risk of cardiovascular disease (CVD) than statin-treated patients who do not have features of the metabolic syndrome.
These results suggest that the residual CVD risk of abdominally obese patients with features of the metabolic syndrome could be further reduced by lifestyle and/or additional pharmacological approaches. Morbidity and mortality trials will be required to test this hypothesis. See the Residual Risk Reduction initiative for further information.
Effects of Weight Loss on Adipose Tissue Distribution
It is well documented that weight loss has a positive effect on all obesity-related metabolic complications (blood pressure, lipids, insulin sensitivity and glucose tolerance, inflammation, etc.). However, because visceral fat is the fat with the strongest ties to the metabolic abnormalities of overweight/obesity, it is important to study the effects of weight loss on body fat distribution and on the amount of visceral fat in particular. Studies have shown that weight loss caused by a low-calorie diet or exercise program can significantly reduce visceral adiposity. The extent of this reduction depends on initial obesity: generally, the greater the initial amount of excess visceral fat, the more visceral fat will be reduced with weight loss. Several studies have reported that moderate weight loss (as little as 5 to 10% of initial body weight) can reduce visceral fat by 10 to 30%. Moreover, for a given amount of weight loss, exercise burns more visceral fat than caloric restriction while preserving lean body mass (skeletal muscle). It is therefore possible to reduce visceral fat without necessarily losing weight. Exercise can reduce visceral fat while increasing lean body mass, causing no change in body weight.
Read more on Effects of Weight Loss on Adipose Tissue Distribution.
Managing Cardiometabolic Risk in Abdominally Obese Patients
Despite evidence that visceral obesity is the most dangerous form of obesity, no study has shown that reducing visceral adipose tissue reduces the risk of cardiovascular outcomes and type 2 diabetes. However, the data available suggests that, regardless of the therapy used (diet, exercise), visceral fat generally decreases when patients with large amounts of this fat lose weight. Although randomized trials with hard endpoints are required to test this hypothesis, a selective reduction of visceral fat has been shown to improve metabolic markers predictive of type 2 diabetes and CHD risk.
Studies have shown that making dietary changes and limiting calorie intake can induce weight loss. The challenge now is to use this knowledge in clinical practice. Most physicians have limited access to additional nutritional expertise to help them reshape the nutritional habits of their patients. The same applies to reshaping exercise habits and prescribing physical activities. Although many studies have shown that regular exercise has a beneficial effect on numerous type 2 diabetes and cardiovascular disease risk factors, few studies have addressed how primary care physicians can implement a lifestyle modification program in the context of a busy clinical practice. However, trials such as the Finnish Diabetes Prevention Study and the American Diabetes Prevention Program have both demonstrated the relevance and value of a lifestyle modification program intended to turn sedentary, abdominally obese, and glucose-intolerant subjects (who are at high risk of type 2 diabetes) into physically active individuals with better nutritional habits. But to successfully lower the risk of diabetes, physicians must be able to refer patients to a multidisciplinary team of dietitians, exercise physiologists, and behaviourists. The move from theory to practice must be made to support patients in their attempts to improve their lifestyle. Providing a supportive, professional environment will enhance the effect of weight loss/waist loss and optimize improvements to cardiometabolic risk factors/markers.
Preventing Type 2 Diabetes
Obesity is a risk factor for type 2 diabetes. However, abdominal obesity has been more closely linked to metabolic complications that increase type 2 diabetes risk than excess body weight. Excess visceral fat has also been shown to precede the development of type 2 diabetes. In this regard, reducing visceral fat through weight loss can improve metabolic risk variables, including glucose-insulin parameters. Several intervention studies have reported that lifestyle modification programs stressing physical activity and healthy eating could substantially reduce the risk of type 2 diabetes in high-risk patients with abdominal obesity and impaired glucose tolerance. These lifestyle modification programs were shown to be remarkably effective despite the fact that they only produced less than a 5% weight loss. By itself, physical activity has a significant metabolic impact by improving indices of plasma glucose-insulin homeostasis, even in the absence of weight loss. Thus, healthcare professionals should focus on reshaping lifestyle habits through increased physical activity and improving overall nutritional quality in order to decrease visceral fat and prevent obesity-related health complications.
Read more on Preventing Type 2 Diabetes.