Mediators of Weight Loss Maintenance in the Keep It Off Trial.

Background: An important step toward enhancing the efficacy of weight loss maintenance interventions is identifying the pathways through which successful interventions such as the Keep It Off trial have worked. Purpose: This study aimed to assess the viability of mediated relationships between the Keep It Off Guided intervention, conceptually and empirically grounded potential mediators, and weight. Repeated measurement of mediators and weight enabled documentation of the temporal ordering of intervention delivery and changes in mediators and in weight among participants randomized to the Guided intervention or Self-Directed comparison group. Methods: Total, direct, and indirect effects of the Guided intervention on weight change were calculated and tested for significance. Indirect effects were comprised of the influence of the intervention on three change scores for each mediator and the relationship between mediator changes and weight changes 6 months later. Results: Guided intervention participants regained about 2% less weight over 24 months than Self-Directed participants. Starting daily self-weighing accounted for the largest share of this difference, followed by not stopping self-weighing. Conclusions: Daily self-weighing mediated 24-month weight loss maintenance. Trial Registration Number: The trial is registered with ClinicalTrials.gov (Identifier: NCT00702455 www.clinicaltrials.gov/ct2/show/NCT00702455).

Resilience to obesity among socioeconomically disadvantaged women: the READI study.

OBJECTIVE: This cross-sectional study aimed to identify sociodemographic and behavioural characteristics of 'overweight-resilient' women, that is, women who were in a healthy body weight range, despite living in socioeconomically disadvantaged neighbourhoods that place them at increased risk of obesity. The study also aimed to test a comprehensive theoretically derived model of the associations between intrapersonal, social and environmental factors and obesity among this target group. PARTICIPANTS: A total of 3235 women aged 18-45 years from 80 urban and rural neighbourhoods throughout Victoria, Australia, participated in the Resilience for Eating and Activity Despite Inequality study. MEASUREMENTS: Women reported height, weight, sociodemographic characteristics, leisure-time physical activity, dietary behaviours and a range of theoretically derived cognitive, social and neighbourhood environmental characteristics hypothesized to influence obesity risk. A theoretical model predicting body mass index (BMI) was tested using structural equation models. RESULTS: Women classified as 'resilient' to obesity tended to be younger, born overseas, more highly educated, unmarried and to have higher or undisclosed household incomes. They engaged in more leisure-time physical activity and consumed less fast foods and soft drinks than overweight/obese women. Neighbourhood characteristics, social characteristics and cognitive characteristics all contributed to explaining variation in BMI in the hypothesized directions. CONCLUSIONS: These results demonstrate several characteristics of women appearing 'resilient' to obesity, despite their increased risk conferred by residing in socioeconomically disadvantaged neighbourhoods. Acknowledging the cross-sectional study design, the results advance theoretical frameworks aimed at investigating obesity risk by providing evidence in support of a comprehensive model of direct and indirect effects on obesity of neighbourhood, as well as social, cognitive and behavioural characteristics.

Changes in C-reactive protein during weight loss and the association with changes in anthropometric variables in men and women: LIFE Study.

OBJECTIVE: To investigate whether sex differences exist in the pattern of change in C-reactive protein (CRP) levels during weight loss, and whether the associations between weight change and CRP change differ by the types of anthropometric variables. DESIGN: Longitudinal, prospective analysis of subjects participating in an intentional weight loss trial (the Lose It For Ever: LIFE Study) followed-up for 30 months. SUBJECTS: A total of 212 healthy, obese men and women (age: 23-77 years, body mass index (BMI): 30-39 kg m(-2)) took part in this study. MEASUREMENTS: BMI, waist and hip circumferences, and waist-to-hip ratio, CRP and lifestyle variables repeatedly measured at baseline, 6, 12, 18 and 30-month follow-up. RESULTS: Weight change was J shaped with a nadir at 12 months in both men and women (P for month(2) <0.0001). CRP level was consistently higher in women than in men, but the differences were less prominent and were not statistically significant at 12- and 18-month follow-up. CRP changes between any two consecutive visits were significantly associated with changes in BMI during the same period in women. However, the associations between CRP changes and changes in waist or hip circumference were not as consistent, especially between 18- and 30-month follow-up when CRP significantly increased. The associations in men were generally similar among the different anthropometric measures. The association between changes in BMI and CRP was stronger in men than in women. CONCLUSION: BMI change generally correlated well with CRP changes in both men and women in the course of follow-up. Significant sex difference in CRP level at baseline diminished at 12- and 18-month follow-up, when both sexes had maintained the lost weight.

Are standard behavioral weight loss programs effective for young adults?

OBJECTIVE: To compare the enrollment, attendance, retention and weight losses of young adults in behavioral weight loss (BWL) programs with older participants in the same trials. METHODS: Data were pooled from three NIH-funded adult BWL trials from two clinical centers in different regions of the country (total N=298); young adults were defined as those aged 18-35 years. Both young adults and adults were compared on session attendance, retention at the 6-month assessment, weight loss and physical activity at 6 months. RESULTS: Young adults represented 7% of the sample, attended significantly fewer sessions than did adults (52 vs 74%, respectively; P<0.001) and were less likely to be retained for the 6-month assessment (67 vs 95%, respectively; P<0.05). Controlling for demographic variables, study and baseline weight, the mean weight losses achieved were significantly less for young adults compared with adults (-4.3 kg (6.3) vs -7.7 kg (7.0), respectively; P<0.05); fewer young adults achieved > or =5% weight loss at 6 months compared with older participants (8/21 (38%) vs 171/277 (62%); P<0.05). After controlling for session attendance, differences in the mean weight loss were not significant (P=0.81). Controlling for baseline values, study and demographics, changes in total physical activity over the initial 6 months of treatment were less for young adults compared with adults, but these differences only approached statistical significance (P=0.07). CONCLUSION: These data indicate that standard programs do not meet the weight control needs of young adults. Research is urgently required to improve recruitment and retention efforts with this high-risk group.

Adherence to a dietary fat intake reduction program in postmenopausal women receiving therapy for early breast cancer. The Women's Intervention Nutrition Study.

PURPOSE: To evaluate the feasibility of integrating a program based on dietary fat intake reduction into adjuvant treatment strategies for postmenopausal women receiving therapy for early breast cancer. PATIENTS AND METHODS: Two hundred ninety postmenopausal women with localized (stage I to IIIa) breast cancer receiving conventional systemic therapy provided informed consent and were randomized in a multicenter trial to either a dietary intervention group receiving a program of individualized instruction for reducing total fat intake or a dietary control group with minimal dietary counseling. RESULTS: Significantly reduced (P < .001) fat intake (in terms of percent calories derived from fat) was observed in the intervention group versus the control group at 3 months (20.3% +/- 2.4% v 31.5% +/- 2.6%, mean +/- SD, respectively) and maintained throughout 24 months of observation. The 50% reduction in daily fat-gram intake (from 66 +/- 23 to 33 +/- 14 g, P < .001) seen at 6 months was associated with reduced saturated fat, monounsaturated fat, polyunsaturated fat, and linoleic acid (P < .001). Significantly lower body weight was also seen in intervention compared with control patients at all observation periods, resulting in a 3.3-kg weight difference 18 months after randomization (P < .001). CONCLUSION: Substantial and sustained dietary fat reduction with associated weight change can be achieved at relatively low cost within the context of conventional multimodality clinical management of postmenopausal women with localized breast cancer. This result supports the feasibility of conducting a full-scale evaluation of the influence of dietary fat intake reduction on the clinical outcome of breast cancer patients.

A prospective study of effects of weight cycling on cardiovascular risk factors.

BACKGROUND: The possible adverse health effects of weight cycling (weight loss followed by weight regain) have been the subject of recent concern. To determine whether such weight cycling negatively influences cardiovascular risk factors, 153 overweight individuals were followed up prospectively through a 30-month weight loss and maintenance program. METHODS: Subjects were divided into seven groups according to their weight-change patterns during this 30-month study (steady weight loss of different magnitudes, weight gain, no change in weight, and different weight-cycling patterns). These weight-change groups were compared with regard to lipid levels, blood pressure measurements, waist-to-hip ratio, and percent body fat at 0, 6, 12, 18, and 30 months. RESULTS: No adverse effects of weight cycling on any of the cardiovascular risk factors were observed. Subjects who initially lost 9.0 kg or more and then regained it did not differ from those who had no change in weight with regard to any cardiovascular risk factor at month 30. Subjects who gained weight during the 30-month interval increased their risk factors, those who lost weight decreased their risk factors in proportion to the magnitude of weight loss, and, in general, cardiovascular risk factors at month 30 were related to the net weight loss achieved and not the route taken to achieve the weight loss. CONCLUSIONS: This study showed no negative effects of weight cycling on cardiovascular risk factors and confirmed previous findings of positive effects of weight loss on risk factors. Therefore, overweight individuals should be encouraged to lose weight and then maintain their weight loss.

Behavioral science research in diabetes: lifestyle changes related to obesity, eating behavior, and physical activity.

Lifestyle factors related to obesity, eating behavior, and physical activity play a major role in the prevention and treatment of type 2 diabetes. In recent years, there has been progress in the development of behavioral strategies to modify these lifestyle behaviors. Further research, however, is clearly needed, because the rates of obesity in our country are escalating, and changing behavior for the long term has proven to be very difficult. This review article, which grew out of a National Institute of Diabetes and Digestive and Kidney Diseases conference on behavioral science research in diabetes, identifies four key topics related to obesity and physical activity that should be given high priority in future research efforts: 1) environmental factors related to obesity, eating, and physical activity; 2) adoption and maintenance of healthful eating, physical activity, and weight; 3) etiology of eating and physical activity; and 4) multiple behavior changes. This review article discusses the significance of each of these four topics, briefly reviews prior research in each area, identifies barriers to progress, and makes specific research recommendations.

Does weight cycling present a health risk?

I review research on the hypothesis that weight fluctuations caused by unsuccessful dieting are hazardous to one's health. Recent epidemiologic findings show that weight variability over time is associated with increased total and cardiovascular mortality (relative risk: 1.5-2.0), independent of a variety of possible confounding variables. Although these findings are consistent across studies, methodologic limitations of a lack of a uniform or standard definition of weight cycling, and the linking of weight variability to unsuccessful dieting raise serous questions about whether these findings should be interpreted as supporting the weight-cycling hypothesis. The absence of data identifying a plausible biological mediator for weight fluctuation per se as a health hazard is also a problem. It is concluded that, although epidemiologic data on weight variability and health are intriguing, they are at present insufficient to alter public health recommendations regarding weight control.

Population perspectives on the prevention and treatment of obesity in minority populations.

Possible causes of population differences in obesity prevalence are discussed: biologic susceptibility, treatment availability or effectiveness, and shared behavior patterns leading to caloric imbalance. It is argued that obesity in minority groups in the United States is best understood as a variation on a larger cultural theme, the creation of an environment in which highly palatable foods are accessible to all at low cost and physical activity is not required. Inequities in access to health education, treatment services, and environmental opportunities are probably responsible for the exacerbation of obesity and its attendant health conditions in some minority groups. Programs for the prevention of obesity in minority populations need to address these inequities and also to consider ways to counteract the historical trends in the United States toward nutritional excess in the population as a whole.

Weight cycling and cardiovascular risk factors in obese men and women.

This study examined the relationship between weight cycling and cardiovascular risk factors in 101 obese men and 101 obese women. Weight cycling was defined in three ways by retrospective self-report: 1) number of previous weight losses of greater than or equal to 4.5 kg, 2) total weight lost in prior weight-loss attempts, and 3) the difference between highest and lowest weight as an adult. Cardiovascular risk factors included blood pressure, total and high-density-lipoprotein cholesterol, triglycerides, fasting and 2-h glucose values, waist-to-hip ratio, and percent of dietary calories from fat. Results did not support the hypothesis that weight cycling increased cardiovascular risk factors in either men or women. Of 88 associations examined, only 7 showed differences with P less than 0.05 and of these, 6 were opposite in direction to that hypothesized. We conclude that warnings about the health hazards of repeated dieting may be premature.

Hypertension prevention trial: do 24-h food records capture usual eating behavior in a dietary change study?

The Hypertension Prevention Trial (HPT) was a randomized unmasked multicenter trial designed to address questions concerning the feasibility and efficacy of dietary intervention in the primary prevention of hypertension. Participants in the diet treatments were given counseling to achieve and sustain changes in calorie, sodium, and/or potassium intake. Diet composition, sodium and potassium excretion, and body weight were assessed for all participants at 6-mo intervals over 3 y. This paper provides information about extent and possible sources of bias in the dietary assessment methodology used in the HPT. Estimates of nutrient intake were derived from food records, urinalysis, and measurement of body weight. Reported potassium intake increased and sodium intake declined to a greater degree during the study than did potassium and sodium excretion. Our results indicate that repeated assessments of diet, which depend upon participant recording, may not accurately represent usual diet in a dietary trial.

Temporal trends in energy intake in the United States: an ecologic perspective.

BACKGROUND: The causes of recent increases in the prevalence of overweight in the United States are perplexing because national survey data do not show clear patterns of change in energy intake or expenditure. OBJECTIVE: Ecologic data regarding the quantities and types of foods and nutrients available in the United States between 1970 and 1998 were reviewed to provide an alternative perspective on trends in energy intake. DESIGN: Literature searches in agriculture, business, and medical library databases were conducted to identify data regarding the quantities and types of foods and nutrients available in the United States between 1970 and 1998. RESULTS: Per capita energy availability estimates from the US Department of Agriculture, US Food Supply Series, indicate that energy availability increased by 15% between 1970 and 1994. Data regarding trends in food purchasing and preparation suggest that Americans are eating more meals outside the home, relying more heavily on convenience foods, and consuming larger food portions. Americans appear, in some cases, to be selecting lower-fat foods over higher-fat alternatives. In addition, availability and sales of reduced-energy and reduced-fat products have increased. CONCLUSION: Consistent with trends in overweight, most of the ecologic data reviewed suggest that energy intake has increased over the past several decades and is likely a major contributor to increases in average body weight.

Unexpected decrease in plasma high density lipoprotein cholesterol with weight loss.

High density lipoprotein (HDL) cholesterol is inversely related to coronary heart disease prevalence. Despite the fact that obese patients have lower plasma HDL-cholesterol concentrations, there are few prospective studies on the effect of weight loss on HDL-cholesterol. Consequently, plasma lipoprotein levels were measured in 15 obese females before and after a 10 week weight loss program. Mean weight loss was 8.6 +/- 3.9 kg (P less than 0.001). Total plasma cholesterol and low density lipoprotein-cholesterol did not change significantly. Plasma triglyceride levels decreased (P less than 0.05) as did HDL-cholesterol (P less than 0.02). A subgroup of 11 of the subjects had repeat lipid measurements 8 months after the start of treatment. Mean weight loss at this time was 12.8 +/- 0.8 kg (P less than 0.01). No subject had returned to her pretreatment weight but mean weight loss was not significantly different from the 10 week value. At 8 months all lipid values, including HDL-cholesterol, had returned to their pretreatment value. By multiple regression analysis HDL-cholesterol decreased with increasing relative weight but also decreased with increasing rate of weight loss. These results suggest that negative caloric balance produces a decrease in HDL-cholesterol that in prospective studies may obscure the inverse relationship between HDL-cholesterol and indices of obesity.

Change in waist-hip ratio with weight loss and its association with change in cardiovascular risk factors.

We investigated whether weight loss decreases the waist-hip ratio (WHR) in overweight men and women, and whether changes in WHR relates to change in cardiovascular risk factors, independent of change in weight. Weight loss correlated significantly with decreases in the circumference of the waist and hips, and decreases in WHR in men and women. At comparable levels of weight loss, men had greater decreases in the waist, and smaller decreases in the hips than women, resulting in greater decreases in WHR. Cardiovascular risk factors improved significantly with weight loss. However, after controlling for weight loss, there was no evidence that change in WHR or change in circumference measures were related to change in risk factors. These data suggest that WHR is modifiable by weight loss, especially in men, but that change in WHR may not be independently related to changes in cardiovascular risk factors.

Weight-loss induced changes in plasma factor VII coagulant activity and relation to the factor VII Arg/Gln353 polymorphism in moderately obese adults.

Elevated plasma factor VII coagulant activity (factor VIIc) may be an independent risk factor for coronary heart disease. Several cross-sectional studies suggest that a polymorphism of the factor VII gene (Arg-Gln353) interacts with plasma triglyceride level in determining factor VIIc, but prospective data are lacking. Factor VII genotype, factor VIIc, and triglyceride level were measured in moderately obese adults aged 25 to 45 who underwent a six-month clinical trial to evaluate strategies for weight loss. A total of 48 men and 50 women who experienced substantial weight loss (mean: 10 kg) provided samples for genetic analysis. Overall, 78% of participants were homozygous for the Arg353 allele, while the remaining 22% were heterozygous (Arg/Gln353). At the baseline examination, heterozygotes had lower mean factor VIIc than Arg353 homozygotes (92% vs. 112%; p<0.001), and genotype explained 18% of the variance of factor VIIc. Average six-month weight loss was similar in both genotypes; mean reductions in factor VIIc following weight loss were greatest among Arg353 homozygotes with high initial values (> 120%). Cross-sectional and longitudinal associations between plasma factor VIIc and triglyceride level were not dependent on genotype. These data confirm that the Gln353 allele is associated with lower factor VII coagulant activity in moderately obese adults, but they do not support the hypothesis that the Arg-Gln353 polymorphism interacts with plasma triglyceride level in determining factor VIIc.

The association of job strain and health behaviours in men and women.

BACKGROUND: This study examined whether self-reported job strain, defined by the Karasek model was associated with some early, potentially modifiable cardiovascular (CVD)-related health characteristics. METHODS: Data were gathered in a 1989 cross-sectional survey of 3843 randomly selected men and women employees of 32 worksites in Minnesota. Sex-stratified crude and multivariate analyses examined the independent association of job psychological demands, latitude, and the combination of these two job domains (i.e. strain), to body mass index (BMI), smoking, exercise, and dietary fat intake. RESULTS: Job demands was positively associated with smoking, smoking intensity, and high fat intake in men and with BMI and smoking intensity in women. Job latitude was positively associated with exercise in men and women. High-strain men smokers smoked more than other workers and high-strain women had higher BMI than other women. CONCLUSIONS: Overall, self-reported job demands, latitude, and job strain were associated with some CVD-related health characteristics, but the effects were not similar in magnitude or direction for all characteristics and they varied by sex.

Payroll contracting for smoking cessation: a worksite pilot study.

Twenty-one men and 38 women participated in a worksite smoking cessation/smoking reduction program that combined financial contracts, organized through payroll deduction, and biweekly group treatment sessions. At the end of the program the smoking cessation rate was 51%, validated by expired air carbon monoxide. Six months later the validated cessation rate was 12%. We conclude that payroll incentives may be effective in helping workers quit smoking and offer suggestions for ways to promote better maintenance of this important behavior change.

Community attitudes toward public policies to control alcohol, tobacco, and high-fat food consumption.

We report the results of a survey conducted in upper-midwestern communities to assess public attitudes toward policy level interventions to moderate the use of alcohol, tobacco, and high-fat food. Four hundred thirty-eight women and 383 men were asked to indicate how much they favored or did not favor 29 policy proposals. Results showed that regulatory controls in all three areas were favored by the general public. Support was strongest for alcohol and tobacco controls, less so for high-fat food. Interventions designed to protect children and youths were most strongly endorsed, followed by restrictions on advertising and direct control over conditions of sale. Women favored all interventions more than men. There was a strong positive association between age and support for measures to moderate alcohol use. Individuals reporting least personal use of alcohol, tobacco, and high-fat foods were most in favor of control policies. The results of this survey indicate specific measures that might be most readily enacted and what segments of the population are likely to be most and least receptive.

Consequences of dieting to lose weight: effects on physical and mental health.

Concern has been raised that negative physiological and psychological effects of dieting may outweigh aesthetic and health benefits. This review of the literature concludes the following: (a) The measurement of dieting is an important unresolved issue; (b) current dieting, chronic dieting, desire to lose weight, specific weight control behaviors, and weight changes may have different effects on health and need to be distinguished; (c) dieting is usually not associated with nutritional deficiencies, adverse physiologic adaptations, severe psychological reactions, or the development of eating disorders; and (d) recommendations against weight loss efforts involving moderate changes in eating and exercise habits are not warranted.

Correspondence programs for smoking cessation and weight control: a comparison of two strategies in the Minnesota Heart Health Program.

Mailed invitations to participate in weight loss and/or smoking cessation correspondence programs to 31,400 households in a suburban community. Two programs were offered to randomized subsets of households, a 6-month correspondence program costing +5 and the same program for free but requiring a +60 deposit to be refunded based on success in weight loss or smoking cessation. Overall, sign-up included 1,304 people for weight loss and 142 for smoking cessation. The +5 program was about 5 times as popular as the incentive program. Validated weight change after 6 months averaged about 4 lb for the +5 program and 8 lb for the incentive program. Corresponding rates of smoking cessation were about 9% and 20%, respectively. We conclude that correspondence programs for the promotion of weight control and smoking cessation are potentially cost-effective methods for reaching individuals in the community at large, many of whom would not be interested in clinic-based programs. Issues meriting further research include recruitment, especially of smokers, and evaluation of the relative trade-offs in recruitment success versus efficacy of differing treatment approaches.