Normal weight obesity and unaddressed cardiometabolic health risk-a narrative review.

Normal weight obesity (NWO) is defined as having a normal body mass index (BMI), but a high body fat mass. There is growing interest in individuals with NWO, which is an underdiagnosed and understudied group, because of their increased risk for cardiometabolic morbidity and mortality. In this review, we summarized the definition, prevalence, etiology, pathophysiology, and cardiovascular outcomes seen in NWO. We have also summarized the available literature on interventions for NWO. There is a wide variation in the body fat percent cutoffs used to diagnose excess body fat. Hence, the prevalence rates of NWO vary between different populations and studies. It is estimated that about 30 million Americans have NWO and the worldwide prevalence ranges from 4.5% to 22%. Genetics, diet, and physical activity are related to NWO. However, etiological factors are not clear. Changes in body composition, inflammation, oxidative stress are present in NWO in comparison to normal weight lean (NWL) who have a normal BMI and normal body fat amount. Furthermore, cardiometabolic changes are observed and some are subclinical. Thus, screening for NWO will enhance the primary prevention of cardiovascular disease. Due to the use of various body fat percent cutoffs and methods to measure body fat, it is challenging to compare between studies. Researchers working in this field should ideally work towards developing standard body fat percent cutoffs for diagnosing NWO. There are many gaps in the literature on NWO unlike for overt obesity and future studies should explore the etiology, molecular mechanisms, and adipose tissue changes of NWO as well as conduct well planned and executed randomized controlled trials testing dietary, physical, and behavioral interventions for NWO in both males and females of different racial and age groups.

A short, attribution theory-based video intervention does not reduce weight bias in a nationally representative sample of registered dietitians: a randomized trial.

BACKGROUND/OBJECTIVES: Weight bias among registered dietitians (RDs) is a concern and effective interventions to reduce weight bias are sparse. Our objective was to determine if a short, attribution theory-based online video intervention would reduce weight bias in RDs. SUBJECTS/METHODS: Dietitians from a nationally representative sample were recruited for a randomized, parallel-arm study with online surveys at pre-, post-intervention and 1-month follow-up. One hundred and forty-seven RDs who watched one of three videos embedded in an online survey from June to August 2019 were considered for the analysis. RDs were randomized to watch either the intervention, positive control, or negative control video. The primary outcome was the change in the "blame" component of the Anti-Fat Attitude Test (AFAT) from pre-to immediate post-intervention. Differences in changes in AFAT and Implicit Association Test (IAT) scores across treatment groups were assessed via linear models; multiple imputation were performed for missing data. RESULTS: Baseline demographics, AFAT and IAT scores of the 147 participants who watched a video were not significantly different between the study groups (p > 0.05). The intervention group's AFAT-blame score reduced by an average of 0.05 between pre- and immediate post-intervention but was not statistically significant (p = 0.76, confidence intervals (CI) = -0.40, 0.30). Furthermore, there were no significant changes for AFAT-social, AFAT-physical subscores, and IAT within or between groups between pre- and immediate post-intervention (p > 0.05). Due to high attrition rates, the changes at 1-month follow-up are not reported. CONCLUSIONS: This study was the first to explore the effectiveness of an online video intervention to reduce weight bias in RDs. This study was unable to detect a significant impact of a short, attribution theory-based video intervention on weight bias in practicing RDs and future larger studies are needed to confirm our findings.

The effects of a teaching intervention on weight bias among kinesiology undergraduate students.

OBJECTIVES: Weight bias is present among kinesiology professionals and this may cause a significant negative impact on their clients with obesity. Thus, our objective was to test if learning about uncontrollable cause of obesity and about weight bias would reduce explicit and implicit weight bias among kinesiology undergraduate students compared to the traditional curriculum which is more focused on controllable causes of weight gain. METHODS: We recruited undergraduates from two classes of the same kinesiology major course taught by the same instructor. In-class teaching activities consisted of 80 min lecture on day 1, video watching session and a group activity on day 3 for both groups. Intervention group (n = 33) learned about uncontrollable causes of obesity and about weight bias and had activities to evoke empathy. Control group (n = 34) learned the traditional curriculum where they learned the role of exercise and diet in weight management. We measured explicit and implicit weight bias using Anti-Fat Attitude Test (AFAT) and Implicit Association Test (IAT), respectively pre-intervention, immediate post intervention and 1 month later. RESULTS: In mixed model analysis, AFAT Blame scores had significant group by time interaction (p < 0.001). Blame scores significantly reduced with mean differences (standard error (SE)) of -0.35 (0.08) post intervention (p < 0.001) and persisted to be reduced with mean differences (SE) of -0.39 (0.08) even after 4-week follow-up (p < 0.001) only in the intervention group. Odds of having less implicit weight bias was significantly lower at 4-week follow-up than pre-intervention (odds ratio = 0.4; 95% CI: 0.22-0.73) in the control group but no changes were seen in the intervention group. CONCLUSIONS: "Blame" component of explicit weight bias significantly decreased when students learned about controllable causes of obesity and weight bias, but implicit bias did not reduce. However, implicit weight bias appears to increase when education on obesity is limited to diet and exercise interventions as taught in the traditional curriculum.

A randomized cross-over trial to determine the effect of a protein vs. carbohydrate preload on energy balance in ad libitum settings.

BACKGROUND: Although high protein diets have been tested in controlled environments for applications to weight management, it is not understood if adding high protein foods to the diet would impact ad libitum energy balance in the absence of other lifestyle changes. METHODS: This double-blinded randomized crossover trial compared the effects of a protein shake (PS) to a carbohydrate shake (CS), consumed prior to each major meal to equate to 20% of total energy needs over the course of the day, on energy balance over two 5-day treatment periods in healthy adults with BMI 20-30 kg/m2. Tri-axial accelerometers estimated physical activity energy expenditure. Ad libitum energy intake was measured in a laboratory kitchen. RESULTS: Energy balance was positive during both treatment periods but was not different between periods. There were no interactions between treatment and preload caloric dose or treatment and BMI status on energy balance. Satiety ratings did not differ for any pairwise comparisons between treatment and caloric dose. Controlling for gender and basal metabolic rate, thermic effect of food was greater for PS than CS. CONCLUSIONS: Preload periods significantly altered the macronutrient composition of the overall diet. This study found limited evidence that carbohydrate or protein preloads have differential effects on energy balance in short-term ad libitum settings. TRIAL REGISTRATION: This trial was pre-registered on clinicaltrials.gov as NCT02613065 on 11/30/2015.

Subjective social status is associated with compensation for large meals - A prospective pilot study.

OBJECTIVES: Subjective social status (SSS) is known to be inversely associated with obesity. Our objective was to determine if SSS is associated with eating behaviors that would predispose to weight gain, specifically, with inadequate compensation for excess energy consumed during a single large meal. Therefore, we conducted a pilot study to determine the association of SSS with 24-h energy balance, 24-h and post-lunch energy intake, changes in body composition and changes in adjusted resting energy expenditure on days when a high-energy lunch was consumed in free-living human subjects. METHOD: Female participants (7 normal weight and 10 overweight) consumed 60% of' estimated 24-h energy requirements as a lunchtime meal in the laboratory for 14 days. Subjective social status was measured at baseline using the MacArthur Scale. Remote Food Photography Method was used to record food intake outside of the lab on days 1-2, 7-8, and 12-13. Associations of 24-h energy balance, 24-h and post-lunch energy intake, changes in adjusted resting energy expenditure and changes in percent body fat (measured by dual x-ray absorptiometry) with SSS were studied. RESULTS: Mean (standard deviation) age and BMI were 36.29 (8.25) years and 26.43 (2.32) kg/m2, respectively. Lower SSS was significantly associated with positive energy balance (p for trend 0.002), and higher post-lunch energy intake (p = 0.02) when controlled for age and initial body mass index. CONCLUSIONS: Our pilot data show that lower SSS is associated with higher post-lunch energy intake, which is indicative of poor energy compensation following a large meal. Over a longer time period, this could result in fat mass gain. Studies that are of longer duration and well-powered are warranted to confirm our findings.

Future Research Directions for the Insurance Hypothesis regarding Food Insecurity and Obesity.

This commentary discusses Nettle et al.'s "The Insurance Hypothesis" linking food insecurity to a high body mass index (BMI). Discussion about how the relationship between race/ethnicity and obesity in the United States is consistent with this hypothesis is presented. Potential ways forward to elucidate the validity of this hypothesis in humans through rigorous controlled trials is highlighted.

Propagation of obesity across generations: the roles of differential realized fertility and assortative mating by body mass index.

BACKGROUND/AIMS: To quantify the extent to which the increase in obesity observed across recent generations of the American population is associated with the individual or combined effects of assortative mating (AM) for body mass index (BMI) and differential realized fertility by BMI. METHODS: A Monte Carlo framework is formed and informed using data collected from the National Longitudinal Survey of Youth (NLSY). The model has 2 portions: one that generates childbirth events on an annual basis and another that produces a BMI for each child. Once the model is informed using the data, a reference distribution of offspring BMIs is simulated. We quantify the effects of our factors of interest by removing them from the model and comparing the resulting offspring BMI distributions with that of the baseline scenario. RESULTS: An association between maternal BMI and number of offspring is evidenced in the NLSY data as well as the presence of AM. These 2 factors combined are associated with an increased mean BMI (+0.067, 95% CI: 0.056; 0.078), an increased BMI variance (+0.578, 95% CI: 0.418; 0.736) and an increased prevalence of obesity (RR 1.032, 95% CI: 1.023; 1.041) and BMIs >40 (RR 1.083, 95% CI: 1.053; 1.118) among offspring. CONCLUSION: Our investigation suggests that both differential realized fertility and AM by BMI appear to play a role in the increasing prevalence of obesity in America.

Potential contributors to variation in weight-loss response to liraglutide.

Obesity treatment requires a chronic state of negative energy balance. Obesity medications can help with this, increasing long-term dietary compliance by promoting satiety or reducing hunger. However, efficacy and safety of obesity medications vary for individuals. Early identification of non-responders to obesity medications may limit drug exposure while optimizing benefits for responders. This review summarizes factors that impact weight-loss response to liraglutide. Factors linked to greater weight loss on liraglutide include being female, not having diabetes, having relatively high baseline weight, and losing at least 4% of initial weight after 16 weeks of treatment. Other covariates that may predict treatment response but require further confirmation include central effects, nausea, gastric emptying of solids, and genotype. Baseline body mass index, race, and age seem less relevant for predicting weight-loss response to liraglutide. Lesser known and harder-to-measure factors such as cerebral blood flow, food cue reactivity, gut hormone levels, and dietary adherence possibly impact variability of response to liraglutide. This information should assist healthcare providers with establishing realistic weight-loss probability for individual patients. Future research should improve the ability to identify responders to liraglutide. Importantly, this review may provide a framework to identify responders to other obesity medications.

Biobehavioural approaches to prevention and treatment: A call for implementation science in obesity research.

Much progress has been made in the last 30 years in understanding the causes and mechanisms that contribute to obesity, yet widely available and successful strategies for prevention and treatment remain elusive at population levels. This paper discusses the biobehavioural framework and provides suggestions for applying it to enable greater progress in the science of obesity prevention and treatment, including an increased focus on implementation of science strategies. The objective is to promote a re-evaluation of current views about preventing and treating obesity within a unified biobehavioural framework. Further integration of research exploring how both behavioural and biological components interact is a critical step forward.

Experimentally Manipulated Low Social Status and Food Insecurity Alter Eating Behavior Among Adolescents: A Randomized Controlled Trial.

OBJECTIVE: This randomized trial experimentally manipulated social status to assess effects on acute eating behavior and 24-hour energy balance. METHODS: Participants (n = 133 Hispanics; age 15-21 years; 60.2% females) were randomized to low social status ("LOW") or high social status ("HIGH") conditions in a rigged game of Monopoly (Hasbro, Inc.). Acute energy intake in a lunchtime meal was measured by food scales. Twenty-four-hour energy balance was assessed via summation of resting metabolic rate (metabolic cart), physical activity energy expenditure (accelerometer), thermic effect of food, and subtraction of twenty-four-hour energy intake (food diary). RESULTS: In the total sample, no significant differences were observed by study condition at lunchtime. LOW females consumed a greater percent of lunchtime daily energy needs (37.5%) relative to HIGH females (34.3%); however, this difference was not statistically significant (P = 0.291). In males, however, LOW consumed significantly less (36.5%) of their daily energy needs relative to HIGH males (45.8%; P = 0.001). For 24-hour energy balance, sex differences were nearly significant (P = 0.057; LOW females: surplus +200 kcal; HIGH males: surplus +445 kcal). Food-insecure individuals consumed a nearly significant greater lunchtime percent daily energy than those with food security (40.7% vs. 36.3%; P = 0.0797). CONCLUSIONS: The data demonstrate differential acute and 24-hour eating behavior responses between Hispanic male and female adolescents in experimentally manipulated conditions of low social status.

Turning Chutes into Ladders for Women Faculty: A Review and Roadmap for Equity in Academia.

Despite significant progress in recent decades, the recruitment, advancement, and promotion of women in academia remain low. Women represent a large portion of the talent pool in academia, and receive >50% of all PhDs, but this has not yet translated into sustained representation in faculty and leadership positions. Research indicates that women encounter numerous "chutes" that remove them from academia or provide setbacks to promotion at all stages of their careers. These include the perception that women are less competent and their outputs of lesser quality, implicit bias in teaching evaluations and grant funding decisions, and lower citation rates. This review aims to (1) synthesize the "chutes" that impede the careers of women faculty, and (2) provide feasible recommendations, or "ladders" for addressing these issues at all career levels. Enacting policies that function as "ladders" rather than "chutes" for academic women is essential to even the playing field, achieve gender equity, and foster economic, societal, and cultural benefits of academia.

Riding into Health: A Case Study on an Equine-Assisted Childhood Obesity Intervention.

In this article, we present an exploratory case study that describes the initial outcomes of the Equine-Assisted Positively Fit (EAPF) program. Children with obesity and their caregivers were recruited to participate in the eight-session program. Results indicated that treatment completers (n = 2) had a decrease in fat mass and fat mass percentage and an increase in fat-free mass and fat-free mass percentage. Moreover, results from accelerometer measurements of physical activity indicated that participants increased their moderate to vigorous physical activity, as well as reported increased self-efficacy for physical activity. Qualitative data from the post-intervention focus group suggested children perceived the treatment acceptable and enjoyable. Findings from this study provide support for future investigations on the feasibility and potential efficacy of pairing children and their caregivers with horses to accomplish health-related goals.

Youth Subjective Social Status (SSS) is Associated with Parent SSS, Income, and Food Insecurity but not Weight Loss Among Low-Income Hispanic Youth.

OBJECTIVE: Subjective social status (SSS), perceived rank in the social ladder, is associated with weight, but determinants of SSS in youth remain unknown. Relationships between youth SSS and income, food insecurity, parent SSS, and BMI change were investigated during an obesity intervention. METHODS: Data came from a family-centered, community-based obesity intervention for low-income families. Parent and youth SSS were assessed using a validated, age-appropriate SSS scale. Food insecurity and socioeconomic factors were assessed in parents; child and parent weight-related data were measured at baseline and post intervention. RESULTS: Participants included 110 primarily Hispanic (97%) low-income youth and their parents. Food insecurity was reported in 66.4% of families. Youth SSS was positively associated with parent SSS (P = 0.0014). In both parents and children, the association between income and SSS was moderated by food insecurity such that lower income was more strongly associated with lower SSS among food-insecure households (P = 0.0286 and P = 0.0327, respectively). Youth SSS was not associated with youth BMI reduction. CONCLUSIONS: Youth SSS was not predictive of weight loss in this intervention. Intriguingly, the association between income and SSS was modified by food insecurity, suggesting that food insecurity shapes the contribution of socioeconomic factors to one's perceived social status.

Body Mass Index and Subjective Social Status: The Coronary Artery Risk Development in Young Adults Study.

OBJECTIVE: Subjective social status (SSS), or perceived social status, may explain, in part, the relationship between socioeconomic status (SES) and obesity. The objective of this study was to test whether SSS mediates the relationship between two indicators of SES (income and education) and body mass index (BMI). METHODS: A cross-sectional, structural equation path analysis was applied to the Coronary Artery Risk Development in Young Adults (CARDIA) study (n = 2,624). The analysis tested whether SSS (MacArthur scale), education, and income were associated with BMI at the year 20 examination (adjusting for sex, age, and race), and it was hypothesized that the associations of education and income with BMI would be at least partly mediated by SSS. RESULTS: SSS had a significant direct effect on BMI (-0.21, P = 0.018). Education had a significant direct relationship with SSS (0.11, P < 0.001) and a small but significant indirect relationship with BMI through SSS (-0.02, P = 0.022). Although income did not have a significant direct relationship with BMI, it did have a significant indirect relationship through SSS (b = -0.05, P = 0.019). CONCLUSIONS: Results are consistent with the hypothesized model in which SSS partially mediates the relationship between SES indicators and BMI.

Longitudinal associations between body mass index, physical activity, and healthy dietary behaviors in adults: A parallel latent growth curve modeling approach.

BACKGROUND: Physical activity (PA) and healthy dietary behaviors (HDB) are two well-documented lifestyle factors influencing body mass index (BMI). This study examined 7-year longitudinal associations between changes in PA, HDB, and BMI among adults using a parallel latent growth curve modeling (LGCM). METHODS: We used prospective cohort data collected by a private company (SimplyWell LLC, Omaha, NE, USA) implementing a workplace health screening program. Data from a total of 2,579 adults who provided valid BMI, PA, and HDB information for at least 5 out of 7 follow-up years from the time they entered the program were analyzed. PA and HDB were subjectively measured during an annual online health survey. Height and weight measured during an annual onsite health screening were used to calculate BMI (kg·m2). The parallel LGCMs stratified by gender and baseline weight status (normal: BMI<25, overweight BMI 25-29.9, and obese: BMI>30) were fitted to examine the longitudinal associations of changes in PA and HDB with change in BMI over years. RESULTS: On average, BMI gradually increased over years, at rates ranging from 0.06 to 0.20 kg·m2·year, with larger increases observed among those of normal baseline weight status across genders. The increases in PA and HDB were independently associated with a smaller increase in BMI for obese males (b = -1.70 and -1.98, respectively), and overweight females (b = -1.85 and -2.46, respectively) and obese females (b = -2.78 and -3.08, respectively). However, no significant associations of baseline PA and HDB with changes in BMI were observed. CONCLUSIONS: Our study suggests that gradual increases in PA and HDB are independently associated with smaller increases in BMI in overweight and obese adults, but not in normal weight individuals. Further study is warranted to address factors that check increases in BMI in normal weight adults.

True, true, unrelated? A review of recent evidence for a causal influence of breakfast on obesity.

PURPOSE OF REVIEW: It has long been known that breakfast skipping is associated with obesity; however, well controlled clinical trials have only recently been conducted to determine a causative relationship. RECENT FINDINGS: Skipping breakfast is likely to be detrimental for insulin sensitivity; however, randomized trials suggest that it does not play a large role in weight gain or weight loss. Specific breakfast strategies such as certain types of breakfast, and consuming more calories in the morning relative to the evening, however, may produce greater weight loss. SUMMARY: The act of eating breakfast, compared to skipping it, does not appear to have a large impact on body weight. More specific strategies regarding the size and type of breakfast may be required for a substantial effect on weight loss, and improving glycemic regulation may be an important reason to consume breakfast rather than skipping it.

The food-insecurity obesity paradox: A resource scarcity hypothesis.

Food insecurity is paradoxically associated with obesity in the United States. Current hypotheses to explain this phenomenon are descriptive regarding the low food security population's dietary and physical activity habits, but are not mechanistic. Herein it is proposed that a resource scarcity hypothesis may explain this paradox, such that fattening is a physiologically regulated response to threatened food supply that occurs specifically in low social status individuals. Evidence that this may be occurring, the implications for addressing the food insecurity-obesity paradox, and future areas of research, are reviewed and discussed.