Albert J. Stunkard

The Body-Mass Index of Twins Who Have Been Reared Apart

To assess the relative importance of genetic and environmental effects on the body-mass index (weight in kilograms divided by the square of the height in meters), we studied samples of identical and fraternal twins, reared apart or reared together. The samples consisted of 93 pairs of identical twins reared apart, 154 pairs of identical twins reared together, 218 pairs of fraternal twins reared apart, and 208 pairs of fraternal twins reared together. The intrapair correlation coefficients of the values for body-mass index of identical twins reared apart were 0.70 for men and 0.66 for women. These are the most direct estimates of the relative importance of genetic influences (heritability) on the body-mass index, and they were only slightly lower than those for twins reared together in this and earlier studies. Similar estimates were derived from maximum-likelihood model-fitting analyses--0.74 for men and 0.69 for women. Nonadditive genetic variance made a significant contribution to the estimates of heritability, particularly among men. Of the potential environmental influences, only those unique to the individual and not those shared by family members were important, contributing about 30 percent of the variance. Sharing the same childhood environment did not contribute to the similarity of the body-mass index of twins later in life. We conclude that genetic influences on body-mass index are substantial, whereas the childhood environment has little or no influence. These findings corroborate and extend the results of earlier studies of twins and adoptees.

An adoption study of human obesity.

We examined the contributions of genetic factors and the family environment to human fatness in a sample of 540 adult Danish adoptees who were selected from a population of 3580 and divided into four weight classes: thin, median weight, overweight, and obese. There was a strong relation between the weight class of the adoptees and the body-mass index of their biologic parents - for the mothers, P less than 0.0001; for the fathers, P less than 0.02. There was no relation between the weight class of the adoptees and the body-mass index of their adoptive parents. Cumulative distributions of the body-mass index of parents showed similar results; there was a strong relation between the body-mass index of biologic parents and adoptee weight class and no relation between the index of adoptive parents and adoptee weight class. Furthermore, the relation between biologic parents and adoptees was not confined to the obesity weight class, but was present across the whole range of body fatness - from very thin to very fat. We conclude that genetic influences have an important role in determining human fatness in adults, whereas the family environment alone has no apparent effect.

Mood Disorders in the Medically Ill: Scientific Review and Recommendations

OBJECTIVE The purpose of this review is to assess the relationship between mood disorders and development, course, and associated morbidity and mortality of selected medical illnesses, review evidence for treatment, and determine needs in clinical practice and research. DATA SOURCES Data were culled from the 2002 Depression and Bipolar Support Alliance Conference proceedings and a literature review addressing prevalence, risk factors, diagnosis, and treatment. This review also considered the experience of primary and specialty care providers, policy analysts, and patient advocates. The review and recommendations reflect the expert opinion of the authors. STUDY SELECTION/DATA EXTRACTION Reviews of epidemiology and mechanistic studies were included, as were open-label and randomized, controlled trials on treatment of depression in patients with medical comorbidities. Data on study design, population, and results were extracted for review of evidence that includes tables of prevalence and pharmacological treatment. The effect of depression and bipolar disorder on selected medical comorbidities was assessed, and recommendations for practice, research, and policy were developed. CONCLUSIONS A growing body of evidence suggests that biological mechanisms underlie a bidirectional link between mood disorders and many medical illnesses. In addition, there is evidence to suggest that mood disorders affect the course of medical illnesses. Further prospective studies are warranted.

Depression and obesity.

The prevalence of depression (10%) and overweight (65%) indicates that there is a probability that they will co-occur, but are they functionally related? This report used the moderator/mediator distinction to approach this question. Moderators, such as severity of depression, severity of obesity, gender, socioeconomic status (SES), gene-by-environment interactions and childhood experiences, specify for whom and under what conditions effects of agents occur. Mediators, such as eating and physical activity, teasing, disordered eating and stress, identify why and how they exert these effects. Major depression among adolescents predicted a greater body mass index (BMI = kg/m(2)) in adult life than for persons who had not been depressed. Among women, obesity is related to major depression, and this relationship increases among those of high SES, while among men, there is an inverse relationship between depression and obesity, and there is no relationship with SES. A genetic susceptibility to both depression and obesity may be expressed by environmental influences. Adverse childhood experiences promote the development of both depression and obesity, and, presumably, their co-occurrence. As most knowledge about the relationship between these two factors results from research devoted to other topics, a systematic exploration of this relationship would help to elucidate causal mechanisms and opportunities for prevention and treatment.

Eating patterns and obesity.

SummaryThis report deals with certain theoretical and clinical aspects of the problem of overeating and obesity. It considers the advantages, especially in psychiatric research, if obesity were found to represent, not one disease, but the end stage of a variety of different conditions with differing etiologies. Experimentally-induced obesity in animals serves as a model of such a contingency since it can be produced by different methods, which result in different types of obesity. Some of the most striking differences have been found in the field of behavior, a recent study having demonstrated characteristic differences between the feeding patterns of obese and non-obese mice, and even between the feeding patterns of mice afflicted with different forms of obesity.The eating behavior of obese human subjects is considered from this point of view, and three distinctive eating patterns are described. The first of these patterns is that of the night-eating syndrome, characterized by morning anorexia, evening hyperphagia, and insomnia. The second pattern is that of the eating binge, in which large amounts of food are consumed in an orgiastic manner at irregular intervals. The third pattern is that of eating-without-satiation which has been observed in persons suffering from damage to the central nervous system.

Parental feeding attitudes and styles and child body mass index: prospective analysis of a gene-environment interaction.

Background. Parental feeding styles were linked to child weight in cross-sectional studies, which were unable to test the direction of effect. Prospective studies can best establish causal relationships among such variables. Objective. We tested the 2-year stability of parental feeding attitudes and styles and investigated whether these variables predict child body mass index (BMI) z scores 2 years later. We evaluated whether these associations were dependent on children’s predisposition to obesity. Methods. Participants were 57 families enrolled in an Infant Growth Study of children born at high risk or low risk for obesity, on the basis of maternal prepregnancy overweight or leanness. Children were evaluated for weight and height at 3, 5, and 7 years of age. Measures of parental feeding attitudes and styles were ascertained with the Child Feeding Questionnaire at 5 and 7 years of age. Correlation and multiple regression analyses tested whether parental feeding styles at age 5 predicted increased child BMI z scores 2 years later. Results. Parental feeding attitudes and styles were stable for child ages of 5 to 7 years. With respect to feeding attitudes, perceived responsibility at age 5 predicted reduced child BMI z scores at age 7 among low-risk families, whereas child weight concern and perceived child weight predicted increased child BMI z scores among high-risk families. With respect to feeding styles, monitoring predicted reduced child BMI z scores at age 7 among low-risk children. In contrast, restriction predicted higher BMI z scores and pressure to eat predicted reduced BMI z scores among high-risk children. These associations remained significant after controlling for child weight status at age 3. Conclusions. The relationship between parental feeding styles and child BMI z scores depends on child obesity predisposition, suggesting a gene-environment interaction. Among children predisposed to obesity, elevated child weight appears to elicit restrictive feeding practices, which in turn may produce additional weight gain. Parenting guidelines for overweight prevention may benefit from consideration of child characteristics such as vulnerability to obesity and current weight status.

Psychological aspects of severe obesity.

Studies of several overweight persons conducted before their undergoing antiobesity surgery have shown 1) that there is no single personality type that characterizes the severely obese; 2) that this population does not report greater levels of general psychopathology than do average-weight control subjects; and 3) that the complications specific to severe obesity include body image disparagement and binge eating. Studies conducted after surgical treatment and weight loss have shown 1) that self-esteem and positive emotions increase; 2) that body image disparagement decreases; 3) that marital satisfaction increases, but only if a measure of satisfaction existed before surgery; and 4) that eating behavior is improved dramatically. The results of surgical treatment are superior to those for dietary treatment alone. Practitioners should be aware that severely obese persons are subjected to prejudice and discrimination and should be treated with an extra measure of compassion and concern to help alleviate their feelings of rejection and shame.

Validation of the flexible and rigid control dimensions of dietary restraint

OBJECTIVE Two subscales for the Eating Inventory (Three-Factor Eating Questionnaire) are developed and validated: Rigid and Flexible control of eating behavior. METHOD Study I is an analysis of questionnaire data and a 7-day food diary of 54,517 participants in a computer-assisted weight reduction program. Study II is a study of 85 subjects used to develop a final item pool. Study III is a questionnaire survey of a random sample (N = 1,838) from the West German population aged 14 years and above used to validate the developed subscales. RESULTS Rigid control is associated with higher scores of Disinhibition, with higher body mass index (BMI), and more frequent and more severe binge eating episodes. Flexible control is associated with lower Disinhibition, lower BMI, less frequent and less severe binge eating episodes, lower self-reported energy intake, and a higher probability of successful weight reduction during the 1-year weight reduction program. DISCUSSION Rigid and flexible control represent distinct aspects of restraint having different relations to disturbed eating patterns and successful weight control.

Social and Psychological Consequences of Obesity

The strong prejudice in this country against obese persons is evident in children as young as 6 years of age. There is discrimination against obese persons in both academic and work settings. Despite this discrimination, overweight persons in the general population show no greater psychological disturbance than do non-obese persons. Similarly, obese patients seen for medical or surgical procedures generally show no more psychopathology than do non-obese patients. Serious psychiatric disturbances associated with obesity include disparagement of body image and negative emotional reactions to dieting. Dieting may also be responsible for the increased incidence of bulimia observed in this country in recent years. Women, adolescent girls, and the morbidly obese appear to suffer the most deleterious consequences of societys contempt for the obese.

Relating body mass index to figural stimuli: population-based normative data for Caucasians.

OBJECTIVE: To establish body mass index (BMI) norms for standard figural stimuli using a large Caucasian population-based sample. In addition, we sought to determine the effectiveness of the figural stimuli to identify individuals as obese or thin.DESIGN: All Caucasian twins born in Virginia between 1915 and 1971 were identified by public birth record. In addition, 3347 individual twins responded to a letter published in the newsletter of the American Association of Retired Persons (AARP). All adult twins (aged 18 and over) from both of these sources and their family members were mailed a 16 page ‘Health and Lifestyle’ questionnaire.SUBJECTS: BMI and silhouette data were available on 16 728 females and 11 366 males ranging in age from 18–100.MEASUREMENTS: Self-report information on height-weight, current body size, desired body size and a discrepancy score using standard figural stimuli.RESULTS: Gender- and age-specific norms are presented linking BMI to each of the figural stimuli. Additional norms for desired body size and discrepancy scores are also presented. Receiver operating curves (ROC) indicate that the figural stimuli are effective in classifying individuals as obese or thin.CONCLUSIONS: With the establishment of these norms, the silhouettes used in standard body image assessment can now be linked to BMI. Differences were observed between women and men in terms of desired body size and discrepancy scores, with women preferring smaller sizes. The figural stimuli are a robust technique for classifying individuals as obese or thin.