Effects of high-sugar and high-fiber meals on physical activity behaviors in Latino and African American adolescents

Vigorous-intensity exercise as a modulator of cardiac adipose tissue in women with obesity: a cross-sectional and randomized pilot study

Cardiac adipose tissue (CAT) has become an important target for the reduction of disease risk. Supervised exercise programs have shown potential to "significantly" reduce CAT; however, the impact of different exercise modalities is not clear, and the relationships between CAT, physical activity (PA) levels and fitness (PFit) remain unknown. Therefore, the purpose of this study was to analyze the relationships between CAT, PA and PFit, and to explore the effects of different exercise modalities in a group of women with obesity. A total of 26 women (age: 23.41 ± 5.78 years-old) were enrolled in the cross-sectional study. PA, cardiorespiratory fitness, muscular strength, body composition and CAT were evaluated. The pilot intervention included 16 women randomized to a control (CON, n=5), high intensity interval training (HIIT, n = 5) and high-intensity circuit training (HICT, n=6) groups. Statistical analysis showed negative correlations between CAT and vigorous PA (VPA) (r s=-0.41, p=0.037); and between percent body fat (%BF), fat mass (FM), and all PA levels (r s=-0.41- -0.68, p<0.05); while muscle mass was positively associated with moderate-to-vigorous PA, and upper-body lean mass with all PA levels (r s =0.40-0.53, p<0.05). The HICT intervention showed significant improvements (p<0.05) in %BF, FM, fat free mass, and whole-body and lower extremities lean mass and strength after three weeks; however, only leg strength and upper extremities' FM improved significantly compared to CON and HICT. In conclusion, although all types of PA showed a positive influence on body fat content, only VPA significantly impacted on CAT volume. Moreover, three weeks of HICT induced positive changes in PFit in women with obesity. Further research is needed to explore VPA levels and high-intensity exercise interventions for short- and long-term CAT management.

The Acute Relationship between Affective States and Stress Biomarkers in Ethnic Minority Youths

Background: Whether affective states acutely predict the hypothalamic–pituitary–adrenal (HPA) axis activities and whether energy balance-related behaviors moderate the affect–HPA axis relationship in obese youths are not well-understood. Methods: 87 mostly obese (94.3% obese) minority adolescents (mean: 16.3 ± 1.2 years old; 56.8% Latino and 43.2% African American) participated in a randomized crossover trial in an observation laboratory, where they received either high-sugar/low-fiber (HSLF) or low-sugar/high-fiber (LSHF) meals first and then crossed over in the next visit 2–4 weeks later. During each visit, they rated five affective states and provided a saliva sample every 30 min for the first 5 h and wore a waist-worn accelerometer. The association between the affect ratings and cortisol levels in the subsequent 30 min and the moderation effect of energy balance-related behavior were examined using multilevel models. Results: Within-person negative affect (β = 0.02, p = 0.0343) and feeling of panic (β = 0.007, p = 0.004) were acutely related to the subsequent cortisol level only during the HSLF condition. The time spent in moderate-to-vigorous physical activity did not moderate the acute relationship between affect and the subsequent cortisol level. Conclusions: Negative affect could be acutely related to heightened HPA axis activities in youths, but only when they were exposed to meals with high sugar and low fiber content. These results suggest that the meals’ sugar and fiber content may modulate HPA axis reactivity to negative affect in youths.

Estimating individualized treatment regimes from crossover designs

The field of precision medicine aims to tailor treatment based on patient-specific factors in a reproducible way. To this end, estimating an optimal individualized treatment regime (ITR) that recommends treatment decisions based on patient characteristics to maximize the mean of a prespecified outcome is of particular interest. Several methods have been proposed for estimating an optimal ITR from clinical trial data in the parallel group setting where each subject is randomized to a single intervention. However, little work has been done in the area of estimating the optimal ITR from crossover study designs. Such designs naturally lend themselves to precision medicine since they allow for observing the response to multiple treatments for each patient. In this paper, we introduce a method for estimating the optimal ITR using data from a 2 × 2 crossover study with or without carryover effects. The proposed method is similar to policy search methods such as outcome weighted learning; however, we take advantage of the crossover design by using the difference in responses under each treatment as the observed reward. We establish Fisher and global consistency, present numerical experiments, and analyze data from a feeding trial to demonstrate the improved performance of the proposed method compared to standard methods for a parallel study design.

Nutritional Status as a Mediator of Fatigue and Its Underlying Mechanisms in Older People

Fatigue is an often-neglected symptom but frequently complained of by older people, leading to the inability to continue functioning at a normal level of activity. Fatigue is frequently associated with disease conditions and impacts health status and quality of life. Yet, fatigue cannot generally be completely explained as a consequence of a single disease or pathogenetic mechanism. Indeed, fatigue mirrors the exhaustion of the physiological reserves of an older individual. Despite its clinical relevance, fatigue is typically underestimated by healthcare professionals, mainly because reduced stamina is considered to be an unavoidable corollary of aging. The incomplete knowledge of pathophysiological mechanisms of fatigue and the lack of a gold standard tool for its assessment contribute to the poor appreciation of fatigue in clinical practice. Inadequate nutrition is invoked as one of the mechanisms underlying fatigue. Modifications in food intake and body composition changes seem to influence the perception of fatigue, probably through the mechanisms of inflammation and/or mitochondrial dysfunction. Here, we present an overview on the mechanisms that may mediate fatigue levels in old age, with a special focus on nutrition.

Objectively-Measured Physical Activity and Sedentary Time are Differentially Related to Dietary Fat and Carbohydrate Intake in Children

Background: Research on the clustering of physical activity, sedentary, and dietary intake behaviors in children has relied on retrospective and parent-report measures, which may obscure true associations. The current study combined objectively-measured moderate-to-vigorous intensity physical activity (MVPA) and sedentary time (ST) data from waist-worn accelerometers, with multiple child-report 24-h dietary recalls to assess specific components of dietary intake (i.e., dietary fat, carbohydrates, protein; glycemic load, fruits and vegetables) in children.

Methods: Participants (n = 136, ages 8–12 years) wore an accelerometer for 7 days. On two of those days, children completed 24-h recall phone interviews to assess dietary intake.

Results: After adjusting for child age, sex, ethnicity, annual household income, and body mass index (BMI) percentile; ST was positively associated with percent dietary fat intake, and negatively associated with percent dietary carbohydrate intake and glycemic load (p's < 0.01). MVPA was positively associated with percent dietary carbohydrate intake and daily glycemic load, and negatively associated with percent dietary fat intake (p's < 0.05).

Conclusion: Despite its direct health benefits, physical activity may be associated with consuming greater proportion of total intake from carbohydrates, especially those with a higher glycemic index. Further research is needed to understand the differential implications of these unique behavioral interrelations for diabetes, cardiovascular, and obesity risk.

The impact of sugar sweetened beverage intake on hunger and satiety in minority adolescents

Limited research has examined the effects of habitual SSB consumption on hunger/fullness ratings and gut hormones. This study hypothesized that high versus low intakes of habitual SSBs would result in greater hunger, decreased fullness, and a blunted gut hormone response, however the high versus low fiber group would exhibit decreased hunger and increased fullness. This was a randomized crossover feeding trial with 47 African American and Hispanic adolescents. The experiment included three 24-hour recalls to assess habitual dietary intake. During the test meal phase, subjects were served breakfast and lunch. During the ad libitum meal phase, subjects were fed an ad libitum dinner. During the test meal phase, blood was drawn every 30 minutes for 3 hours. During the ad libitum meal phase, hunger and fullness visual analogue scales were completed. For this analysis, subjects were grouped into the following habitual SSB categories: low SSB (≤1 SSB serv/day), medium SSB (>1 - <2 serv/day), and high SSB (≥2 serv/day). Fiber categories were created based on quartiles of intake. Mixed modeling was used to explore how SSB and fiber categories predicted ghrelin/PYY values and hunger/fullness ratings across time within and between test meals. The following a priori covariates included: sex, ethnicity, age, and obesity status. The low SSB group had higher fullness ratings over the ad libitum meal compared to the high SSB group (β =-0.49, CI=(-0.89, -0.08), p=0.02) and higher ghrelin concentrations than the medium and high SSB group over the test meal phase (β =-1.86, CI=(-2.81, -0.92), p<0.01). Habitual SSB intake appears to play a key role in moderating fullness responses possibly via ghrelin.