Obesity and Mental Disorders

Susan L. McElroy, David B. Allison, George A. Bray, Susan L. McElroy, David B. Allison, George A. Bray

• Publisher: CRC Press
• Year: 2006
• Print ISBN: 9780367453893
• eBook ISBN: 9781000611366
• Topic: Medicine
• Subtopic: Endocrinology & Metabolism

Currently, there are a limited amount of guidelines to help clinicians manage patients with obesity and comorbid mental disorders. This expertly written source fills the gap in the literature by providing a clear overview of obesity and its relationship to mental illness while reviewing the most recent methods to manage and control the condition wi

Part I: Overview of Obesity

1

Obesity Is a Major Health Problem: Causes and Natural History

George A. Bray

Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, Louisiana, U.S.A.

OVERVIEW OF OBESITY

How fat are we? Before we can answer this question and discuss its implications, we need a definition of what we mean by fatness or obesity. Obesity means too much body fat, but because body fat is affected by age and sex, it has proven more effective to use a surrogate relating height and weight called the body mass index (BMI). This is measured as the weight in kilograms (kg) divided by the stature in meters (m) squared (kg/m²). The BMI is largely independent of height and provides a reasonable assessment of fatness. The normal range of BMI is 18.5 to 24.9 kg/m². Overweight is defined as a BMI between 25 and 29.9 kg/m², and obesity as a BMI >30 kg/m² (1,2).

Using the BMI, the prevalence of obesity can be assessed around the world. In the United States, 60.4% of the adult population aged 20 to 74 is overweight and 30.5% are obese in the most recent survey of the American population by the National Center of Health Statistics (3,4). The epidemic is worldwide and is affecting children as well as adults (1,5). It is against this background of a rising prevalence of obesity that strategies to prevent and treat obesity need to be developed.

A careful analysis of the shifting distribution curves for body weight shows that most of the increase is in the upper half of the distribution curve, which skews body weight to the heavy side. This would suggest that the people at risk for obesity in the current epidemic are people in the upper part of the body weight distribution curve who have a genetic susceptibility to store fat in our society of nutritional abundance. These people probably begin to gain weight in childhood and then continue into adult life (6,7). This environmental response of genetically susceptible people to nutritional abundance has been labeled as a “toxic environment” (8).

In this overview of obesity, it is important to start with a number of realities for obesity that underlie the problem. These are briefly summarized below:

• Obesity is a chronic, relapsing, stigmatized disease that is increasing in prevalence.
• It is due to an imbalance between energy intake and energy expenditure.
• Treatments rarely cure obesity.
• The therapeutic armamentarium of physicians is limited and labors under the negative halo of treatment mishaps.
• Drugs do not work when they are not taken.
• Weight loss plateaus on any treatment when compensatory mechanisms come into play.
• Frustration with plateaued weight that often averages less than 10% leads to discontinuing therapy, then to weight regain and labeling the weight loss program as a failure.

The current epidemic of obesity is a time bomb for future development of diabetes and its many complications. As such, it deserves efforts at prevention and, where needed, treatment. The disease of obesity has its pathology rooted in the enlargement of fat cells. Secretory products of these enlarged fat cells produce most of the pathogenetic changes that result in the complications associated with obesity. Physicians and the health care system have two strategies to deal with this problem. The first is to prevent the development of obesity, or to reverse it before the complications develop. Alternatively, the health care system can wait until the complications develop and then institute appropriate therapy. With the current high quality therapies available to treat hypertension, diabetes mellitus, and hypercholesterolemia, many physicians would prefer this latter strategy. However, if treatment for obesity were effective, the former approach would clearly be preferable. In one long-term trial, the incidence of new cases of diabetes was reduced to zero over two years in patients who lost and maintained a weight loss of 12% or more compared to an incidence of 8.5% for new cases of diabetes in those who did not lose weight. Thus, effective treatment can have a major impact in reducing the risk of developing serious diseases in the future.

One reason that most physicians are reluctant to treat obese patients is that their treatments are limited in number and effectiveness. At this writing, there are only two drugs approved by the United States Food and Drug Administration for long-term use in obesity. As monotherapy, both agents can produce a weight loss of 8% to 10%. However, to achieve the reduction in the rate of new cases of diabetes noted above, the weight loss needs to exceed 12%, a goal that cannot be easily achieved with current monotherapy. Thus, there is a great need for new treatment to be used when prevention fails.

Obesity is a stigmatized disease. One commonly held view is that obese people are lazy and weak-willed. If fat people just had willpower, they would push themselves away from the table and not be obese. This widely held view is shared by the public and by health professionals alike. The clamoring of women to be lean and well proportioned supports this view. The declining relative weight of centerfold models in Playboy and of women who are winners of the Miss America contest also supports this view. Many physicians just do not like to see obese patients come into their offices. Dealing with this problem will pose a major challenge to any efforts to improve the lot of people who are obese.

Two other issues aggravate the problem of treating obesity. The first is the “negative halo” that surrounds the use of appetite suppressants because amphetamine is addictive. There was never any evidence that dexfenfluramine was addictive. Nonetheless, the drug was scheduled by the United States Drug Enforcement Agency as a Schedule IV drug because on paper it had chemical similarities to amphetamine.

The second issue is the concern about the plateau of body weight that is reached when homeostatic mechanisms in the body come into play and stop further weight loss. There is an analogy with treatment of hypertension. When an antihypertensive drug is given, blood pressure drops and then stops falling within a few weeks to reach a “plateau” at a new lower level. The antihypertensive drug has not lost its effect when the plateau occurs, but its effect is being counteracted by physiological mechanisms designed to maintain blood pressure. In the treatment of obesity, a similar plateau in body weight is often viewed as a therapeutic failure for the weight loss drug. This is particularly so when weight is regained when the drug is stopped. These attitudes and biases need to change before any effective new therapy will become widely accepted.

The final issue is the disaster that recently befell many patients who took the combination of fenfluramine and phentermine. Aortic regurgitation occurred in up to 25% of the patients treated with this combination of drugs and led many physicians to say “I told you so” and “I’m certainly glad I did not use those drugs.” Much of this will subside with time, but there will remain a residue of concern among some physicians and among regulators about the potential problems that might surface when new treatments for obesity are made available to the public.

THE CAUSES OF OBESITY

Etiologic Classification

A number of specific etiologies that cause obesity are described further.

Psychological and Social Factors

Psychological factors in the development of obesity are widely recognized, although attempts to define a specific personality type that causes obesity have been unsuccessful. One condition linked to weight gain is seasonal affective disorder, which refers to the depression that occurs during the winter season in some people living in the north, where days are short. These patients tend to increase body weight in winter. This can be effectively treated by providing higher-intensity artificial lighting in the winter (9).

Behavioral Patterns of Eating

Restrained eating: A pattern of conscious limitation of food intake is called “restrained” eating (10). It is common in many, if not most, middle-age women of “normal weight.” It may also account for the inverse relationship of body weight to social class; women of upper socioeconomic status often use restrained eating to maintain their weight. In a weight-loss clinic, higher restraint scores were associated with lower body weights (11). Weight loss was associated with a significant increase in restraint, indicating that higher levels of conscious control maintain lower weight. Greater increases in restraint correlate with greater weight loss, but also with higher risk of “lapse” or loss of control and overeating.

Binge eating disorder: Binge eating disorder is a psychiatric illness characterized by uncontrolled episodes of overeating, usually in the evening (12). The patient may respond to treatment with drugs that modulate serotonin.

Night eating syndrome: Night eating syndrome is the consumption of at least 25% (and usually more than 50%) of energy between the evening meal and the next morning (13,14). It is one pattern of disturbed eating in the obese. It is related to sleep disturbances and may be a component of sleep apnea, in which day-time somnolence and nocturnal wakefulness are...

Table of contents

• Cover
• Half Title
• Series Page
• Title Page
• Copyright Page
• Preface
• Table of Contents
• Contributors
• Part I: Overview of Obesity
• Part II: Relationship Between Obesity and Psychopathology
• Part III: Behavioral Treatments of Obesity with and Without Psychopathology
• Part IV: Medical Treatments of Obesity with and Without Psychopathology
• Index
• About the Editors