Biomedical subjects

Donald A Williamson

Publications and source records attributed to Donald A Williamson.

At least 19 recordsLinked to original sources

PubMed2006

Measurement of dietary restraint: validity tests of four questionnaires.

This study tested the validity of four measures of dietary restraint: Dutch Eating Behavior Questionnaire, Eating Inventory (EI), Revised Restraint Scale (RS), and the Current Dieting Questionnaire. Dietary restraint has been implicated as a determinant of overeating and binge eating. Conflicting findings have been attributed to different methods for measuring dietary restraint. The validity of four self-report measures of dietary restraint and dieting behavior was tested using: (1) factor analysis, (2) changes in dietary restraint in a randomized controlled trial of different methods to achieve calorie restriction, and (3) correlation of changes in dietary restraint with an objective measure of energy balance, calculated from the changes in fat mass and fat-free mass over a six-month dietary intervention. Scores from all four questionnaires, measured at baseline, formed a dietary restraint factor, but the RS also loaded on a binge eating factor. Based on change scores, the EI Restraint Scale was the only measure that correlated significantly with energy balance expressed as a percentage of energy required for weight maintenance. These findings suggest that, of the four questionnaires tested, the EI Restraint Scale was the most valid measure of the intent to diet and actual caloric restriction.

Adult↗

PubMed2006

Weight-related concerns associated with smoking in young children.

Studies have shown that weight concern is associated with smoking in adolescents. However, little is known about the relationship between weight concern and smoking in younger children. Analyses were conducted to determine whether children in elementary school who had tried smoking would possess greater weight concern than those who had not tried smoking. Results indicated that smokers possessed more general weight concern, F(1, 640)=5.619, p=.018, reported more dieting, F(1, 707)=11.757, p=.001, and endorsed greater concern with body size, F(1, 707)=4.113, p=.043, than non-smokers. Similar to adolescents, these results suggest that young children who have tried smoking are more concerned about weight than children who have not tried smoking.

Adolescent↗

PubMed2006

Effect of 6-month calorie restriction on biomarkers of longevity, metabolic adaptation, and oxidative stress in overweight individuals: a randomized controlled trial.

CONTEXT: Prolonged calorie restriction increases life span in rodents. Whether prolonged calorie restriction affects biomarkers of longevity or markers of oxidative stress, or reduces metabolic rate beyond that expected from reduced metabolic mass, has not been investigated in humans. OBJECTIVE: To examine the effects of 6 months of calorie restriction, with or without exercise, in overweight, nonobese (body mass index, 25 to <30) men and women. DESIGN, SETTING, AND PARTICIPANTS: Randomized controlled trial of healthy, sedentary men and women (N = 48) conducted between March 2002 and August 2004 at a research center in Baton Rouge, La. INTERVENTION: Participants were randomized to 1 of 4 groups for 6 months: control (weight maintenance diet); calorie restriction (25% calorie restriction of baseline energy requirements); calorie restriction with exercise (12.5% calorie restriction plus 12.5% increase in energy expenditure by structured exercise); very low-calorie diet (890 kcal/d until 15% weight reduction, followed by a weight maintenance diet). MAIN OUTCOME MEASURES: Body composition; dehydroepiandrosterone sulfate (DHEAS), glucose, and insulin levels; protein carbonyls; DNA damage; 24-hour energy expenditure; and core body temperature. RESULTS: Mean (SEM) weight change at 6 months in the 4 groups was as follows: controls, -1.0% (1.1%); calorie restriction, -10.4% (0.9%); calorie restriction with exercise, -10.0% (0.8%); and very low-calorie diet, -13.9% (0.7%). At 6 months, fasting insulin levels were significantly reduced from baseline in the intervention groups (all P<.01), whereas DHEAS and glucose levels were unchanged. Core body temperature was reduced in the calorie restriction and calorie restriction with exercise groups (both P<.05). After adjustment for changes in body composition, sedentary 24-hour energy expenditure was unchanged in controls, but decreased in the calorie restriction (-135 kcal/d [42 kcal/d]), calorie restriction with exercise (-117 kcal/d [52 kcal/d]), and very low-calorie diet (-125 kcal/d [35 kcal/d]) groups (all P<.008). These "metabolic adaptations" (~ 6% more than expected based on loss of metabolic mass) were statistically different from controls (P<.05). Protein carbonyl concentrations were not changed from baseline to month 6 in any group, whereas DNA damage was also reduced from baseline in all intervention groups (P <.005). CONCLUSIONS: Our findings suggest that 2 biomarkers of longevity (fasting insulin level and body temperature) are decreased by prolonged calorie restriction in humans and support the theory that metabolic rate is reduced beyond the level expected from reduced metabolic body mass. Studies of longer duration are required to determine if calorie restriction attenuates the aging process in humans. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT00099151.

Adult↗

PubMed2006

Two-year internet-based randomized controlled trial for weight loss in African-American girls.

OBJECTIVE: A randomized controlled trial tested the efficacy of an internet-based lifestyle behavior modification program for African-American girls over a 2-year period of intervention. RESEARCH METHODS AND PROCEDURES: Fifty-seven overweight (mean BMI percentile, 98.3) African-American girls (mean age, 13.2 years) were randomly assigned to an interactive behavioral internet program or an internet health education program, the control condition. Overweight parents were also participants in the study. Forty adolescent-parent dyads (70%) completed the 2-year trial. Outcome data including BMI, body weight, body composition, and weight loss behaviors were collected at baseline and at 6-month intervals. A computer server tracked use of the web sites. RESULTS: An intention-to-treat statistical approach was used, with the last observation carried forward. In comparison with the control condition, adolescents in the behavioral program lost more mean body fat (BF) (-1.12 +/- 0.47% vs. 0.43 +/- 0.47% BF, p < 0.05), and parents in the behavioral program lost significantly more mean body weight (-2.43 +/- 0.66 vs. -0.35 +/- 0.64 kg, p < 0.05) during the first 6 months. This weight loss was regained over the next 18 months. After 2 years, differences in fat for adolescents (-0.08 +/- 0.71% vs. 0.84 +/- 0.72% BF) and weight for parents (-1.1 +/- 0.91 vs. -0.60 +/- 0.89 kg) did not differ between the behavioral and control programs. DISCUSSION: An internet-based weight management program for African-American adolescent girls and their parents resulted in weight loss during the first 6 months but did not yield long-term loss due to reduced use of the web site over time.

Adipose Tissue↗

PubMed2006

Comparison of body composition methods in obese African-American women.

OBJECTIVE: To compare the accuracy of percentage body fat (%BF) estimates between bioelectrical impedance analysis (BIA) and DXA in obese African-American women. RESEARCH METHODS AND PROCEDURES: Fifty-five obese African-American women (mean age, 45 years; mean BMI, 38; mean %BF, 48%) were studied. BF was assessed by both BIA (RJL Systems BIA 101Q; RJL Systems, Clinton Township, MI) and DXA (Hologic QDR-2000 Bone Densitometer; Hologic Inc., Bedford, MA). Generalized and ethnicity- and obese-specific equations were used to calculate %BF from the BIA. Bland-Altman analyses were used to compare the agreement between the BIA and the DXA, with the DXA serving as the criterion measure. RESULTS: Two of the generalized equations provided consistent estimates across the weight range in comparison with the DXA estimates, whereas most of the other equations increasingly underestimated %BF as BF increased. One of the generalized and one of the ethnicity-specific equations had mean differences that were not significantly different from the DXA value. DISCUSSION: The findings show that the Lukaski equation provided the most precise and accurate estimates of %BF in comparison with the QDR 2000 and provide preliminary support for the use of this equation for obese African-American women.

Absorptiometry, Photon↗

PubMed2006

Psychological adjustment during Army basic training.

This study evaluated changes in depression, anxiety, and stress during Army basic training. During week 1 of training, 139 soldiers from two companies volunteered for participation. In week 8, 93 soldiers were available for retesting. Self-reports of depressive symptoms and perceptions of stressfulness at both assessments fell within the normative range for nonclinical samples, whereas endorsement of anxiety symptoms remained slightly elevated, in the mild range. Women endorsed higher levels of anxiety (F = 8.87, p < 0.01) than did men. No gender or ethnicity differences were noted for changes in psychological distress over time. Regression analyses showed that subjects with the highest levels of initial distress on the anxiety, depression, and stress measures had the most change at the end of 8 weeks of training (r values between 0.61 and 0.39; all p < 0.01). Results suggest that initial levels of psychological distress are slightly elevated for anxiety but most individuals adapt to the stress of basic training, with normal levels of distress by the last week.

Adaptation, Psychological↗

PubMed2006

The effect of proposed improvements to the Army Weight Control Program on female soldiers.

OBJECTIVE: To comply with Army Regulation 600-9, The Army Weight Control Program (AWCP), soldiers must meet age-adjusted body fat standards, regardless of whether they meet or exceed weight-for-height allowances. Recent revisions to Department of Defense (DoD) policies require changes to the AWCP. Specifically, we assessed the effects of increasing weight-for-height allowances and adoption of the DoD body fat equation on compliance with the AWCP in women. METHODS: Weight, height, circumferences (neck, forearm, wrist, waist, and hip) to measure body fat, and Army Physical Fitness Test results were obtained from 909 female soldiers (mean (SD) age, 26.2 (6.5) years; body mass index, 24.6 (3.3) kg/m2; body fat, 29.7% (5.0)). RESULTS: Increasing the screening weight-for-height allowances resulted in a 20% reduction in those requiring a body fat measurement (from 55% [n = 498) to 35% [n = 319]). Adopting the DoD body fat equation did not change the proportion of overfat women, i.e., noncompliant with the AWCP, (from 26% [n = 232] to 27% [n = 246]). More women with a waist circumference > 35 inches (i.e., at increased disease risk) were identified as noncompliant with the AWCP by the proposed body fat equation (from 76% [n = 61] to 96% [n = 77]). CONCLUSIONS: Proposed changes reduce the proportion of women unnecessarily measured for body fat and do not change the proportion of women on the AWCP, yet select more women at increased disease risk and most in need of an effective intervention.

Adipose Tissue↗

PubMed2005

Effects of consuming mycoprotein, tofu or chicken upon subsequent eating behaviour, hunger and safety.

This study tested if: (1) a preload of mycoprotein and tofu consumed before a lunch meal have a greater effect on satiety when compared to a chicken preload, (2) the mycoprotein and tofu preloads, compared to chicken, are not associated with compensation or eating more food at a subsequent dinner meal. These hypotheses were tested in a controlled laboratory study using universal eating monitors to measure food intake and visual analogue scales to monitor hunger and satiety. Forty-two overweight adult females consumed three meals in the laboratory on 3 test days. At lunch, isocaloric pasta preloads, containing mycoprotein, tofu, or chicken, varied across the days in a balanced order. The findings of the study supported the two hypotheses. Mycoprotein and tofu preloads, in comparison to the chicken preload, were associated with lower food intake shortly after consuming the preload at lunch. Food intake following consumption of mycoprotein and tofu did not differ, and participants did not compensate for lower food intake at lunch by consuming more food at dinner. The findings suggest that mycoprotein and tofu have satiating properties that persist for several hours after a meal. These findings have significant implications for the development of foods that are low in kilojoules, but are also filling.

Adolescent↗

PubMed2005

The diet and health knowledge survey: development of a short interview format.

The primary aim of this study was to create a condensed short-form version of the structured interview named the Diet and Health Knowledge Survey (DHKS 1994-1996) via factor analysis. Data from 5765 participants of the 1994-1996 Diet and Health Knowledge Survey were used in the factor analysis. Appropriate sampling weights were used in the multivariate analyses (n=5233) that compared subgroups (i.e., ethnic group, sex, etc.) on the subscales of the DHKS. A 50-item, 12-factor condensed version of the 149-item original DHKS was derived from the analyses. Multivariate analyses, using age and education as covariates, indicated significant differences in dietary beliefs, practices, and behaviors for individuals of different ethnic groups, sex, dieting status, and BMI. Based on our analyses, the condensed short-form version of the Diet and Health Knowledge Survey appears to be a convenient and efficient tool, used in sections or in its entirety, for examining various dietary practices and beliefs of adults. The results from analysis of the short-form DHKS indicate that although a very large proportion of adults in the U.S. are overweight or obese, only a small proportion report current dieting. Examination of the DHKS indicates that although adults varied in their dietary beliefs and practices, dieters tended to report healthier dietary practices and attitudes than non-dieters. BMI level was positively related to self-reported amount of fat, cholesterol, and calories consumed.

Adult↗

PubMed2005

Consistency of food intake over four eating sessions in the laboratory.

OBJECTIVE: The aim of this study was to test the consistency (repeatability) of laboratory measures of food intake, including eating microstructure (cumulative food intake curves), in non-obese humans across four eating sessions, each separated by 1 week. A secondary aim was to test the effect of dietary restraint on the food intake of female participants. METHODS: Mixed model analyses were used to compare average food intake across sessions, and intraclass correlation coefficients (ICC) were employed to compare within subject variability to total variance. High and low restraint females and low restraint males consumed four lunches in a Universal Eating Monitor (UEM) laboratory. The lunches consisted of one type of sandwich (chicken salad sandwich squares) or three types of sandwiches (chicken salad, ham, and turkey sandwich squares) presented in counterbalanced order. RESULTS: Measures of food intake were stable for men and women, regardless of sandwich variety. In females, level of dietary restraint (high vs. low) did not significantly affect food intake. DISCUSSION: The results indicate that eating behavior in the laboratory is sufficiently stable over time to justify evaluation of interventions designed to alter food intake using within subject designs.

Adolescent↗

PubMed2005

Categorical versus dimensional models of eating disorders: an examination of the evidence.

OBJECTIVE: Eating disorders have been conceptualized as discrete syndromes or categories and as dimensions that differ in degree among individuals. Until recently, researchers have not directly addressed which of these models, categorical versus dimensional, is most valid. METHODS: The primary objective of this review was to examine the evidence related to the validity of dimensional versus categorical models of eating disorders. RESULTS: Findings from a series of taxometric studies have suggested that a conceptual representation of eating disorders may involve a latent taxon, related to binge eating (and possibly purging), and one or more dimensions. These studies found that binge eating was identified as a factor that does not occur on a continuum with anorexia nervosa, restricting subtype. Restricting subtype anorexia is continuous with normalcy, however. DISCUSSION: These findings should be viewed as preliminary evidence that may have implications for the etiology, assessment, prevention, and treatment of eating disorders.

Factor Analysis, Statistical↗

PubMed2005

Microanalysis of eating behavior of three leptin deficient adults treated with leptin therapy.

Leptin deficiency has been associated with extreme obesity and hyperphagia in rodents and humans. A rare genetic disorder in humans yields the absence of the hormone leptin, extreme obesity, and a ravenous appetite. Reports on these rare cases have indicated that therapy using leptin injections can yield significant weight loss and changes in appetite. The aim of this report on acute leptin therapy in three leptin deficient adults was to provide a microanalysis of changes in eating behavior and ratings of hunger and satiety. In addition to substantial weight loss, 15 weeks of leptin therapy was associated with approximately 50% reduction in food intake and substantial changes in ratings of hunger and satiety before most meals. After short-term leptin therapy, the three participants ate until ratings indicated they were satiated, which was comparable to the ratings before leptin therapy. These findings suggest that one of the primary effects of acute leptin therapy may be to reduce the ravenous hunger associated with leptin deficiency, resulting in reduced food intake and significant weight loss. These results are discussed in the context of the scientific literature pertaining to leptin and its effects on appetite and obesity.

Adult↗

PubMed2005

Behavior and lifestyle: approaches to treatment of obesity.

The increasing prevalence of overweight and obesity in adults and children demonstrates a steadily growing epidemic. This rising rate of obesity is associated with obesity related comorbidities including cardiovascular disease, hypertension, some cancers, joint disease, and particularly, type 2 diabetes. Modest weight loss (5% to 10% of total body weight) through lifestyle intervention approaches has been found to have a beneficial effect on comorbid conditions, particularly hypertension and type 2 diabetes. Effective behavioral treatment of obesity involves modification of eating and physical activity patterns to yield negative energy balance. Research studies have found that interventions that combine a low-calorie diet, increased physical activity, and behavior therapy are most effective for weight loss and maintenance. Furthermore, extended length of treatment contact, weight loss satisfaction, and social support may promote positive long-term outcomes in obese adults and children.

Adolescent↗

PubMed2004

Psychological aspects of eating disorders.

Eating disorders (anorexia nervosa, bulimia nervosa, and binge eating disorder) are regarded as psychiatric syndromes that have some relationship to obesity. This review describes current clinical and scientific knowledge concerning the clinical descriptions of these disorders, etiology of each disorder, diagnostic signs, and treatment approaches that have been found to be efficacious. Anorexia nervosa is a very serious eating disorder that is associated with severe medical complications. Anorexia nervosa is very difficult to successfully treat, even when intensive inpatient methods are used. Bulimia nervosa and binge eating disorder are typically less severe eating disorders and are more easily treated using outpatient therapy. Pharmacotherapy has not been found to be an effective treatment for anorexia nervosa, but it has been used successfully with bulimia nervosa and binge eating disorder. Psychotherapy approaches have been successfully employed for all three eating disorders. The review concludes with an integrative perspective that illustrates the similarities and differences of the eating disorders and obesity.

Continuity of Patient Care↗

PubMed2004

Mediators of weight loss in a family-based intervention presented over the internet.

OBJECTIVE: To assess the process variables involved in a weight loss program for African-American adolescent girls. Several process variables have been identified as affecting success in in vivo weight loss programs for adults and children, including program adherence, self-efficacy, and social support. The current study sought to broaden the understanding of these process variables as they pertain to an intervention program that is presented using the Internet. It was hypothesized that variables such as program adherence, dietary self-efficacy, psychological factors, and family environment factors would mediate the effect of the experimental condition on weight loss. RESEARCH METHODS AND PROCEDURES: Participants were 57 adolescent African-American girls who joined the program with one obese parent; family pairs were randomized to either a behavioral or control condition in an Internet-based weight loss program. Outcome data (weight loss) are reported for the first 6 months of the intervention. RESULTS: Results partially supported the hypotheses. For weight loss among adolescents, parent variables pertaining to life and family satisfaction were the strongest mediating variables. For parental weight loss, changes in dietary practices over the course of 6 months were the strongest mediators. DISCUSSION: The identification of factors that enhance or impede weight loss for adolescents is an important step in improving weight loss programs for this group. The current findings suggest that family/parental variables exert a strong influence on weight loss efforts for adolescents and should be considered in developing future programs.

Absorptiometry, Photon↗

PubMed2004

A new dental approach for reducing food intake.

OBJECTIVE: A behavioral recommendation for weight loss is reduction of size of bites of food. This "proof of concept" study tested the efficacy of a new, patented, dental approach, the DDS System, for reducing food intake. This removable tool is inserted into the upper palate of the mouth, reducing the size of the oral cavity, thereby potentially reducing bite size. RESEARCH METHODS AND PROCEDURES: Thirty-two adults (18 to 65 years) with BMI between 27 and 40 were randomly assigned to the control or experimental conditions. Participants ate all meals and stayed between meals at a research center. Day 1 served as baseline for both groups. On Day 2, experimental participants utilized the tool during meals. Changes in subjective ratings of hunger and satiety were measured using visual analog scales before and after each meal. RESULTS: Food intake difference scores were calculated for each participant (Day 2 - Day 1). Analysis of covariance on difference scores, using baseline as a covariate, showed that the experimental group ate significantly less (p < 0.05) on the second day (M = -659.2 kcal/d) compared with the control group (M = -125.9 kcal/d). Analysis of covariance, with ratings on Day 1 as a covariate, revealed that the experimental and control group did not differ on visual analog scale difference scores (premeal - postmeal) from Day 1 to Day 2. DISCUSSION: These findings suggest that use of this tool during meals significantly reduced food intake. This reduction of food intake was not associated with changes in ratings of hunger or satiety.

Adult↗

PubMed2004

Cognitive-behavioral theories of eating disorders.

This article presents an integrated cognitive-behavioral theory of eating disorders that is based on hypotheses developed over the past 30 years. The theory is evaluated using a selected review of the eating disorder literature pertaining to cognitive biases, negative emotional reactions, binge eating, compensatory behaviors, and risk factors for eating disorders. In general, hypotheses derived from cognitive-behavioral theories have been supported by a variety of research studies. The implications of these findings for treatment and prevention of eating disorders are discussed. This review of the literature serves as a conceptual base for some of the other articles that are included in this special issue of Behavior Modification. The article concludes with an introduction to six articles that discuss issues related to psychiatric classification, assessment, treatment, and prevention of eating disorders.

Cognitive Behavioral Therapy↗

PubMed2004

Multidisciplinary treatment of eating disorders--Part 2: Primary goals and content of treatment.

This article describes the program content of a multidisciplinary, hospital-based program for severe eating disorders. Common goals for treatment of patients with eating disorders are discussed. Details about the specific therapeutic strategies used in individual and group therapy are provided. Also, information about dietary counseling and exercise prescription is described. This article is the second in a two-part article. The first article (Stewart & Williamson, 2004, this issue) described the structural organization and costs associated with this multidisciplinary treatment program.

Counseling↗