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Obesity, Weight Loss, and Cardiovascular Disease

Introduction

As you might already know, cardiovascular disease (CVD) is the most prevalent cause of disability and death in the western world. There are some risk factors for CVD that are beyond anyone’s control such as age and gender. For instance, men who are 55 years or older, and women who are 65 years or older, are at increased risk for getting coronary artery disease (CAD). CAD is caused by atherosclerosis which is hardening of the lining of the arteries that give the blood supply to the heart muscle. If one of these arteries becomes blocked, part of the heart muscle dies and a heart attack occurs.

On the other hand, there are multiple risk factors for CAD that are under the control of the individual. These include hypertension, diabetes mellitus, cigarette smoking, obesity and a sedentary lifestyle.

The topic of obesity is complicated by the interplay between genetic and environmental factors. For instance, one can find families where the parents and children are all obese. This clearly looks like a genetic predisposition. However, when one observes the family’s lifestyle, it may be that all family members eat a poor diet and get little exercise.

This article will explore the definition of obesity and will describe alternatives for weight reduction. Dietary information will be provided with links to multiple educational websites. Referral to professional dieticians will be made available. Information regarding exercise programs will be described. Finally, information regarding bariatric surgery and gastric banding will be provided in the event that conservative measures fail.

What is obesity?

When one comes to the office to be evaluated, the nurse takes one’s height and weight. This information is fed into a computer program that calculates the body mass index (BMI). This calculation is made as follows:

BMI = body weight (in kg) / square of height (in meters).

From this information one falls into categories as follows:

20-25 Kg/m2 = little or no risk
25-30 Kg/m2 = low risk
30-35 Kg/m2 = moderate risk
35-40 Kg/m2 = high risk
>40 Kg/m2 = very high risk
It should be noted that the distribution of fat is important. If it is concentrated primarily in the midsection, it is termed “visceral fat.” This places one at higher risk. If one’s belly is the first thing to go through the doorway as one enters a room, their cardiovascular risk is increased. (See http://www.cgh.org/body.cfm?id=148&fr=true for information on calculating BMI).

Another method for evaluating one’s cardiovascular risk with respect to obesity is the calculation of the waist to hip ratio (WHR). One’s waist and hip circumference is measured with a tape measure. A WHR of 0.7 for women and 0.9 for men predicts a more favorable cardiovascular outlook. Higher ratios predict adverse outcomes.

What are the consequences of obesity?

The American Heart Association has identified obesity as an independent risk factor for coronary artery disease. As one becomes more obese, there is also a direct effect on other risk factors for CAD as well. For instance, as the BMI increases there is an increase seen in blood pressure, LDL (bad) cholesterol and diabetes mellitus.

For example, The Nurses’ Health Study was performed in the United States which evaluated 115,195 women. This study noted a significant trend for increasing risk of death with increasing BMI. In fact, the study found that a weight gain of 4.5 lbs. or more after 18 years of age was associated with an increased risk of death in middle adulthood.

Why does obesity increase cardiovascular risk?

It appears that obesity increases risk by interacting with other risk factors in the individual patient.

Abdominal (visceral) obesity causes the insulin that is pumped into the blood stream from the pancreas to be less effective. This is called insulin resistance. When this is seen together with abnormal lipid levels (high LDL, low HDL and high triglycerides), hypertension and diabetes mellitus, the patient is considered to have the Metabolic Syndrome. This is associated with an increased risk of sustaining a cardiovascular event.

Obesity is associated with an increase in blood volume. This combines with high blood pressure to cause the heart muscle to thicken (left ventricular hypertrophy). When this occurs the risk of heart failure and death caused by a heart attack are increased.

Obesity is also associated with obstructive sleep apnea. This can result in high blood pressure and heart muscle dysfunction. This can result in increased death rates. (See cgh_sleepcenter_mailer.pdf for information on assessing sleep apnea).
What are the benefits of weight loss?

Weight loss has been shown to significantly improve one’s blood pressure, reduce the incidence of diabetes mellitus and improve one’s cholesterol profile. For example, in one study of over 28,000 women with no known heart disease, an intentional weight loss of 20 lbs. was associated with a decreased death rate due to cardiovascular disease or cancer.

What are the pitfalls associated with weight loss?

Unfortunately, even when one is successful in losing weight there is a significant tendency to regain the weight. This is called recidivism. When this occurs the patient is back where he started with the same level of risk as described above.

Management of obesity

Every patient that comes for an office visit can expect to have his height and weight measured so that the Body Mass Index (BMI) can be computed. Counseling on weight management will be offered. If necessary a referral to a registered dietician will be made. The plan will be to implement a diet that is appropriate for the individual taking into consideration whether or not the patient has diabetes mellitus. Each patient can expect counseling on an exercise program as this will be an important aspect of any weight loss strategy. Ultimately, if conservative measures fail and the patient is an appropriate candidate, gastric bypass surgery or banding might become a consideration. (See www.cgh.org/lifestyle for a life action plan run by dieticians at CGH).
(See  http://www.utdol.com/online/content/topic.do?topicKey=bariat/4797&selectedTitle=2%7E150&source=search_result for detailed information on bariatric surgery).

Exercise

Physical exercise is the act of using major muscle groups to perform activities of daily living or for the goal of improving or maintaining physical fitness. Routine activities could include the ability to walk in a store or to climb stairs. On the other hand, exercise to improve physical fitness is the process one goes through to attain the ability to perform tasks with ample energy and to avoid fatigue. This allows one to pursue leisure activities.

In the United States there is an epidemic of obesity and diabetes mellitus. One reason for this is the sedentary lifestyles many Americans lead. Statistics show that approximately 24% of adults in the United States do any leisure time physical activity. The recommended amount of physical activity is considered to be at least 30 minutes of moderate physical activity at least 5 days per week. However, this is actually done by slightly less than half of all Americans. To improve physical fitness, decrease obesity and aid in treatment of diabetes mellitus:

 

 ( See http://www.uptodate.com/patients/content/topic.do?topicKey=~..V.7xZpjMS5xF for an excellent review of patient information on physical exercise).

Behavioral management of obesity

The initial management of obesity involves life style intervention. In addition to diet and exercise, this is required for long term success with weight loss.

The purpose of behavioral management is to make long term changes in one’s eating behavior. One has to learn to modify and monitor their food intake. Regular exercise must be involved as noted above. One must learn what cues in the environment trigger eating behavior and ways in which these stimuli can be controlled.

It must be recognized that while behavioral management of obesity is considered to be essential to any weight loss program, there are significant challenges to success with this approach. Weight loss utilizing behavioral programs range from 7 % to 10% of initial body weight. However, maintenance of the weight lost has been difficult.

One way in which the success of behavioral weight loss programs has improved is by increasing the length of treatment. By increasing the duration of treatment, the amount of weight loss can be up to 18.7 lbs. after 21 weeks.

In order to implement behavioral treatment for the overweight patient, one has to examine certain assumptions and expectations. Obese individuals have learned eating and exercise patterns that have contributed to and that have maintained their overweight state. The hope of the behavioral management of obesity is that through long term changes in diet, exercise and behavioral conditioning successful long term weight loss can be achieved.

Many obese people have tried to lose weight on almost an annual basis. However, despite searching for and trying to implement new ways to lose weight the long term result is often unsatisfactory. A cycle develops characterized by failure and renewal of effort. Failure occurs because the person’s expectations often exceed what is feasible. They have unrealistic predictions that change will occur more easily than is possible. People also tend to overestimate their abilities or are unaware that they are inaccurate. It is common for people to believe that making a change will improve their lives more than can reasonably be expected.

Given these road blocks, there are several elements of a behavioral strategy that can be employed with the hope of accomplishing significant weight loss. People should learn methods of self-monitoring. Food diaries and activity records should be kept. The stimuli that activate eating behavior should be controlled. A goal of learning to slow down the eating process should be set. Nutritional education and meal planning are essential to success. A program of physical exercise needs to be implemented and maintained. It is certainly helpful to have a social support system in place.

With these principles in mind, lifestyle intervention is considered to be essential in the treatment of obesity. A combination of diet, exercise and behavioral treatment needs to be implemented for success.
(See http://www.aafp.org/afp/2001/0601/p2185.html for an excellent article on the behavioral management of weight loss.)

Surgical management of severe obesity

If your body mass index (BMI) is >30 kg/m2, you are considered to be obese. Obesity is a chronic disease that has increased in prevalence in the U.S. and worldwide. For instance, statistics show that the percentage of obese men doubled between 1991 and 1998. The number of obese women increased by 50% in the same time frame.

A general principal that doctors adhere to when treating a patient with a disease is to first, “Do No Harm.” The second principal is to start with treatments that are easily administered with low risk. If the treatment is not effective and more needs to be done, a more extensive strategy is devised that may entail more risk.

These principles apply to weight management. Diet and exercise are always tried first. However, if the patient is obese and these conservative measures fail, the surgical management for severe obesity becomes an option.

What is the effectiveness of bariatric surgery?

The goal of bariatric surgery is to head off the complications that occur from being obese and ultimately to reduce the risk of death. This can be achieved with successful surgery as metabolic and organ function improves. Other benefits that accrue from successful surgery include reducing monthly medication costs, reducing the number of sick days, and an overall improvement in the quality of life.

Studies have shown that the average overall weight loss from surgery is 61%. Diabetes completely resolves in 77% of patients, or at least improves in 86%. Hyperlipidemia (high cholesterol) improves in 70%. Hypertension completely resolves in 62% and improves in 79%. Obstructive sleep apnea resolves in 86%.

What are the risks of bariatric surgery?

Depending on the type of operation, the risk of death with surgery ranges from 0.1% to 1.1%.

What are the indications for the surgical management of obesity?

A candidate for this type of surgery needs to be well-informed and motivated.
The BMI should be>40.
The risk of surgery should be acceptable.
Non-surgical attempts at weight loss should have been tried without success.
Patients with a BMI of >35 should also be considered for surgery if the have diabetes, sleep apnea, and other comorbidities.

For a comprehensive discussion of the surgical management of obesity (See http://www.weightlosssurgeryoptions.com/). For a good consumer guide to bariatric surgery (See http://www.yourbariatricsurgeryguide.com/).

Mark A. Rothschild, MD, FACC