The Effects of a High-Carbohydrate versus a High-Fat Shake on Biomarkers of Metabolism and Glycemic Control When Used to Interrupt a 38-h Fast: A Randomized Crossover Study

This study aimed to determine the impact of various fast-interrupting shakes on markers of glycemic control including glucose, β-hydroxybutyrate (BHB), insulin, glucagon, GLP-1, and GIP. Twenty-seven sedentary adults (twelve female, fifteen male) with overweight or obesity completed this study. One condition consisted of a 38-h water-only fast, and the other two conditions repeated this, but the fasts were interrupted at 24 h by either a high carbohydrate/low fat (HC/LF) shake or an isovolumetric and isocaloric low carbohydrate/high fat (LC/HF) shake. The water-only fast resulted in 135.3% more BHB compared to the HC/LF condition (p < 0.01) and 69.6% more compared to the LC/HF condition (p < 0.01). The LC/HF condition exhibited a 38.8% higher BHB level than the HC/LF condition (p < 0.01). The area under the curve for glucose was 14.2% higher in the HC/LF condition than in the water condition (p < 0.01) and 6.9% higher compared to the LC/HF condition (p < 0.01), with the LC/HF condition yielding 7.8% more glucose than the water condition (p < 0.01). At the 25-h mark, insulin and glucose-dependent insulinotropic polypeptide (GIP) were significantly elevated in the HC/LF condition compared to the LC/HF condition (p < 0.01 and p = 0.02, respectively) and compared to the water condition (p < 0.01). Furthermore, insulin, GLP-1, and GIP were increased in the LC/HF condition compared to the water condition at 25 h (p < 0.01, p = 0.015, and p < 0.01, respectively). By the 38-h time point, no differences were observed among the conditions for any of the analyzed hormones. While a LC/HF shake does not mimic a fast completely, it does preserve some of the metabolic changes including elevated BHB and glucagon, and decreased glucose and insulin compared to a HC/LF shake, implying a potential for improved metabolic health.

Time Spent Jogging/Running and Biological Aging in 4458 U.S. Adults: An NHANES Investigation

Telomere length is a good index of cellular aging. Longer telomeres are predictive of longer life, and healthy lifestyles are associated with longer telomeres. This study explored the relationship between time spent jogging or running each week and leukocyte telomere length (LTL) in 4458 randomly selected U.S. adults. The association was studied using data collected by the National Health and Nutrition Examination Survey (NHANES), and a cross-sectional design. Total weekly jog/run time was calculated from survey responses. From the minute totals, three categories were formed: <10 min/week, 10-74 min/week, and ≥75 min/week. Adults in the third category met the U.S. guidelines. Data were analyzed using one-way ANOVA. Partial correlation was used to adjust for differences in potential mediating factors, including demographic and lifestyle/medical factors. In the total sample, after adjusting for all the potential covariates, mean LTL significantly differed across the three jog/run categories (F = 4.1, p = 0.0272). Specifically, adults who met the guidelines via jogging and/or running had significantly longer telomeres than adults who performed no jogging/running. Adults in the middle category did not differ from the other two categories. A minimum of 75 min of jogging/running weekly is predictive of longer telomeres when compared to adults who do not jog or run regularly.

Weight Change over Ten Years Predicts Biological Aging in a Random Sample of 3070 U.S. Adults

This investigation was designed to study the relationship between weight change over 10 years and leukocyte telomere length (LTL) in a large sample of 3070 randomly selected U.S. adults, 36-70 years old. The National Health and Nutrition Examination Survey (NHANES) data were used to examine the relationship between percent weight change and LTL. Potential mediating variables were controlled using partial correlation. After adjusting for age, race, year, and housing status, the association between percent weight change over 10 years and LTL was significant in women (F = 6.9, p = 0.0138). Adjusting for the demographic and several other covariates weakened the relationship slightly (F = 4.7, p = 0.0392). With all the covariates controlled, for each one percentage point increase in weight over the previous 10 years, telomeres were, on average, 3.48 base pairs (bp) shorter in women. Given that each one-year increase in age was associated with telomeres that were 15.0 bp shorter in women, the median weight change in U.S. women over the previous 10 years (an increase of 10.4%) was predictive of LTLs that were 36 bp shorter, on average, or an increase of 2.4 years of biological aging. Percent weight change over 10 years was not associated with LTL in U.S. men. Percent weight change over 10 years is a strong predictor of biological aging in U.S. women, but not in men.

Relationship between Sitting Time and Insulin Resistance in 6931 U.S. Adults: The Mediating Role of Abdominal Adiposity

This cross-sectional investigation examined the relationship between sitting time and insulin resistance in 6931 U.S. adults. The mediating effects of several covariates were evaluated. Self-reported sitting time, measured in minutes per day, was the exposure variable. Insulin resistance (IR), indexed using the natural log of the homeostatic model assessment of insulin resistance (L-HOMA-IR), was the outcome variable. This study used data collected from the 2011-2018 National Health and Nutrition Examination Survey (NHANES). Results showed a strong, positive, dose-response association between sitting time and insulin resistance after adjusting for age, sex, race, and year of assessment (F = 12.6, p < 0.0001). Across the sitting time tertiles (low, moderate, and high), the L-HOMA-IR means (±SE) each differed from each other (0.37 ± 0.008, 0.40 ± 0.012, and 0.43 ± 0.012). Further controlling for cigarette smoking and physical activity did not alter the significance of the relationship. Adding body mass index (BMI) to the demographic covariates weakened the relationship, but it remained significant. However, the association was no longer significant after adjusting for the demographic covariates and waist circumference (F = 1.1, p = 0.3349). None of the L-HOMA-IR means (±SE) differed from each other (0.40 ± 0.007, 0.41 ± 0.009, and 0.41 ± 0.008). Overall, waist circumference was a powerful mediating variable between sitting time and insulin resistance. Apparently, time spent sitting is a powerful predictor of IR. However, much of the association between sitting time and IR is a function of differences in waist size. As a strong measure of abdominal adiposity and a significant predictor of multiple metabolic diseases, managing waist size is a health practice to consider when insulin resistance is a concern.

The Effects of Exercise on Appetite-Regulating Hormone Concentrations over a 36-h Fast in Healthy Young Adults: A Randomized Crossover Study

Hunger and satiety are controlled by several physiological mechanisms, including pancreatic and gastrointestinal hormones. While the influence of exercise and fasting have been described individually, in relation to these hormones, there is a paucity of work showing the effects of the two modalities (fasting and exercise) combined. Twenty healthy adults (11 males, 9 females) completed both conditions of this study, each consisting of a 36-h water-only fast. One of the fasts began with treadmill exercise, and the differences between the conditions on various appetite hormones were measured every 12 h. The difference in the area under the curve between conditions for ghrelin was 211.8 ± 73.1 pg/mL (F = 8.40, p < 0.0105), and, for GLP-1, it was -1867.9 ± 850.4 pg/mL (F = 4.82, p < 0.0422). No significant differences were noted for areas under the curve between conditions for leptin, PP, PYY, insulin, or GIP. Initiating a fast with exercise lowers ghrelin concentrations and elevates GLP-1 concentrations. Given that ghrelin elicits feelings of hunger and GLP-1 signals feelings of satiety, adding exercise to the beginning of a fast may reduce some of the biological drive of hunger, which could make fasting more tolerable, leading to better adherence and more significant health outcomes.

Legume Intake, Body Weight, and Abdominal Adiposity: 10-Year Weight Change and Cross-Sectional Results in 15,185 U.S. Adults

There were three objectives: (1) evaluate the relationship between legume intake and weight change across the previous 10 years, (2) examine the cross-sectional associations between legume consumption, BMI, and abdominal adiposity, and (3) determine if the relationship between legume intake and the outcomes were influenced by multiple covariates, particularly fiber intake. The sample included 15,185 randomly selected adults representative of the U.S. population. Percent change in weight was used as the outcome measure for the 10-year analysis. BMI, and waist circumference, corrected for height, were employed as the outcomes for the cross-sectional analyses. Legume, fiber, and energy intakes were measured using the average of two 24-h dietary recalls. Legume intake was divided into three categories. Five demographic and five lifestyle covariates were controlled statistically. There was an inverse dose-response relationship between legume intake and percent weight change over the previous 10 years after adjusting for 9 of the covariates (F = 6.5, p = 0.0028). However, after controlling for fiber with the other covariates, there were no differences across the three legume intake groups (F = 1.9, p = 0.1626). The cross-sectional findings showed similar inverse dose-response results until fiber intake was controlled. Then the associations became non-significant. In conclusion, legume intake is a good predictor of percent weight change over the previous 10 years, and it is also a significant predictor of BMI and abdominal adiposity cross-sectionally. These relationships are strongly influenced by fiber consumption. Evidently, legumes have dietary advantages, especially high fiber levels, that seem to be valuable in the battle against weight gain and obesity.

The effects of daily step goals of 10,000, 12,500, and 15,000 steps per day on neural activity to food cues: A 24-week dose-response randomized trial

INTRODUCTION

The purpose of this study was to examine the effect of different levels of sustained physical activity on neural reflections of attention allocated toward food cues in first year college women.

METHODS

Seventy-nine first-year college women (18.6 ± 0.5 years) were recruited to participate in the study. Women were randomly assigned to a daily step goal of 10,000, 12,500, or 15,000 for 24 weeks. Once during weeks 16-24, participants were shown pictures of plated meals or flowers with the neural response measured using the P300 and late positive potential (LPP) components of the scalp-recorded event-related potential. Diet was assessed using the automated 24-h recall.

RESULTS

Both the P300 and LPP amplitudes were significantly more positive to food versus flower pictures (ps < .001). There was no interaction between step group and picture condition for the P300 and LPP. However, the 12,500-step group showed a significantly elevated LPP amplitude in comparison to the other groups for both food and flowers (F(2,74) = 8.84; p < .001). The effect size for the combined results (food and flowers) was 0.56 between 10,000 and 12,500-step groups, and 0.75 between the 12,500- and 15,000-step groups. In addition, the 12,500 group reduced caloric consumption over the course of the intervention (t(1,74) = 3.35, p = .001, d_z  = 0.59).

CONCLUSION

Habitual physical activity of 10,000, 12,500, or 15,000 steps per day does not preferentially alter neural reflections toward food cues compared to flowers. There may be a nonlinear response to pleasant visual cues, with 12,500 steps per day eliciting higher LPPs than either 10,000 or 15,000.

Serum, Dietary, and Supplemental Vitamin D Levels and Insulin Resistance in 6294 Randomly Selected, Non-Diabetic U.S. Adults

The primary aim of this study was to determine the associations between serum, dietary, and supplemental vitamin D levels and insulin resistance in 6294 non-diabetic U.S. adults. A total of 8 years of data from the 2011−2018 National Health and Nutrition Examination Survey (NHANES) and a cross-sectional design were utilized to answer the research questions. Serum vitamin D levels were quantified using high-performance liquid chromatography−tandem mass spectrometry. Dietary and supplemental vitamin D intakes were assessed using the average of two 24 h dietary recalls taken 3−10 days apart. The homeostatic model assessment (HOMA), based on fasting glucose and fasting insulin levels, was employed to index insulin resistance. Demographic covariates were age, sex, race, and year of assessment. Differences in physical activity, body mass index (BMI), cigarette smoking, body weight, season, and energy intake were also controlled statistically. Serum levels of vitamin D differed significantly, and in a dose−response order, across quartiles of HOMA-IR, after adjusting for year, age, sex, and race (F = 30.3, p < 0.0001) and with all the covariates controlled (F = 5.4, p = 0.0029). Dietary vitamin D levels differed similarly across HOMA-IR quartiles, but to a lesser extent, respectively (F = 8.1, p = 0.0001; F = 2.9, p = 0.0437). Likewise, supplemental vitamin D levels also differed across the HOMA-IR quartiles, respectively (F = 3.5, p = 0.0205; F = 3.3, p = 0.0272). With all the covariates controlled, the odds of having insulin resistance were significantly greater for those in the lowest quartile of serum and supplemental vitamin D intake compared to the other quartiles combined. In conclusion, in this nationally representative sample, serum, dietary, and supplemental vitamin D were each predictive of insulin resistance, especially in those with low serum levels and those with no supplemental intake of vitamin D.

Macronutrient Intake and Insulin Resistance in 5665 Randomly Selected, Non-Diabetic U.S. Adults

The main goal of this investigation was to evaluate the relationships between several macronutrients and insulin resistance in 5665 non-diabetic U.S. adults. A secondary objective was to determine the extent to which the associations were influenced by multiple potential confounding variables. A cross-sectional design and 8 years of data from the 2011–2018 National Health and Nutrition Examination Survey (NHANES) were used to answer the research questions. Ten macronutrients were evaluated: total carbohydrate, starch, simple carbohydrate, dietary fiber, total protein, total fat, saturated, polyunsaturated, monounsaturated, and total unsaturated fat. The homeostatic model assessment (HOMA), based on fasting glucose and fasting insulin levels, was used to index insulin resistance. Age, sex, race, year of assessment, physical activity, cigarette smoking, alcohol use, and waist circumference were used as covariates. The relationships between total carbohydrate intake (F = 6.7, p = 0.0121), simple carbohydrate (F = 4.7, p = 0.0344) and HOMA-IR were linear and direct. The associations between fiber intake (F = 9.1, p = 0.0037), total protein (F = 4.4, p = 0.0393), total fat (F = 5.5, p = 0.0225), monounsaturated fat (F = 5.5, p = 0.0224), and total unsaturated fat (F = 6.5, p = 0.0132) were linear and inversely related to HOMA-IR, with 62 degrees of freedom. Starch, polyunsaturated fat, and saturated fat intakes were not related to HOMA-IR. In conclusion, in this nationally representative sample, several macronutrients were significant predictors of insulin resistance in U.S. adults.

10-Year Weight Gain in 13,802 US Adults: The Role of Age, Sex, and Race

PURPOSE

The primary objective of the present investigation was to identify 10-year weight gain patterns in 13,802 US adults and also to determine the extent that differences in 10-year weight gains were associated with the key demographic variables: age, sex, and race.

METHODS

The study design was cross-sectional and included the years 2011-2018. Data for 2019-2020 were not available because of COVID. A multistage random sampling strategy was employed. Specifically, individual sample weights and randomly selected clusters and strata were used with each statistical model, allowing the results to be generalized to the US adult population.

RESULTS

Mean (±SE) 10-year weight gain was 4.2 ± 0.2 kg or 6.6 ± 0.2% of initial body weight. A total of 51% of the participants gained 5% or more body weight, 36% gained 10% or more, and 16% gained 20% or more across the 10-years. Age was linearly and inversely associated with 10-year weight gain, expressed in kg (F = 166.4, P < 0.0001) or percent weight gain (F = 246.9, P < 0.0001), after adjusting for sex and race. For each 1-year increase in age, 10-year weight gain decreased by 0.20 ± 0.02 kg and 0.28 ± 0.02 percent. After adjusting for age and race, 10-year weight gain (kg) was significantly greater (F = 73.6, P < 0.0001) in women (5.4 ± 0.3) than in men (2.6 ± 0.2). Weight gain also differed across races, kg (F = 27.7, P < 0.0001) and % (F = 28.5, P < 0.0001). Non-Hispanic Blacks gained more weight and NH Asians gained less weight than the other races.

CONCLUSION

Without question, 10-year weight gain is a serious problem within the US adult population. Younger adults, women, and Non-Hispanic Blacks, particularly Black women, seem to experience the highest levels of 10-year weight gain. Consequently, obesity and weight gain prevention programs focusing on these at-risk individuals should be a public health priority.

The Effects of Exercise on β-Hydroxybutyrate Concentrations over a 36-h Fast: A Randomized Crossover Study

PURPOSE

This study assessed β-hydroxybutyrate (BHB) concentration during a short-term fast and the degree to which an initial bout of exercise influences the rate of ketogenesis.

METHODS

Twenty subjects (11 male, 9 female) completed two 36-h fasts, with one protocol requiring the subject to complete a treadmill exercise session at the beginning of the fast. BHB levels were assessed via portable meter every 2 h, along with mood and hunger ratings. Venipuncture was performed every 12 h.

RESULTS

The mean (SD) areas under the curve for BHB concentration were 19.19 (2.59) mmol·L-1 (nonexercised) and 27.49 (2.59) mmol·L-1 (exercised), yielding a difference of 8.30 mmol·L-1 between conditions (95% posterior probability interval (PPI), 1.94 to 14.82 mmol·L-1; posterior probability (PP) = 0.99). The mean (SD) times to BHB concentration of 0.5 mmol·L-1 were 21.07 (2.95) h (nonexercised) and 17.5 (1.69) h (exercised), a 3.57-h difference (95% PPI, -2.11 to 10.87 h; PP = 0.89). The differences in area under the curve between conditions were 5.07 μU·mL-1 (95% PPI, -21.64 to 36.18 μU·mL-1; PP = 0.67) for insulin, 97.13 pg·mL-1 (95% PPI, 34.08 to 354.21 pg·mL-1; PP = 0.98) for glucagon, and 20.83 (95% PPI, 4.70 to 24.22; PP = 0.99) for the insulin/glucagon ratio.

CONCLUSIONS

Completing aerobic exercise at the beginning of a fast accelerates the production of BHB throughout the fast without altering subjective feelings of hunger, thirst, stomach discomfort, or mood. Insulin and the insulin/glucagon ratio experience a marked reduction within the first 12 h of fasting and was not altered with exercise. Thus, exercising at the beginning of a fast may improve the metabolic outcomes of fasting.

Acute after-school screen time in children decreases impulse control and activation toward high-calorie food stimuli in brain regions related to reward and attention

The purpose of this study was to examine the effects of after-school sedentary screen time on children's brain activation in reward and cognitive control regions in response to pictures of high- and low-calorie foods. Thirty-two children participated in a randomized crossover study with counterbalanced treatment conditions. Conditions took place on separate days after school and included three hours of active or sedentary play. After each condition, neural activation was assessed using functional magnetic resonance imaging (fMRI) while participants completed a go/no-go task involving pictures of high- and low-calorie foods. General response inhibition was also measured using the Stroop task. Hunger was measured upon arrival to the testing facility and just prior to fMRI scans. Mixed effects models were used to evaluate main effects and interactions. Significant stimulus by condition interactions were found in the right superior parietal cortex, and left anterior cingulate cortex (Ps ≤ 0.05). High-calorie pictures elicited significantly more activation bilaterally in the orbitofrontal cortex compared to low-calorie pictures (Ps ≤ 0.05). Stroop task performance diminished significantly following the sedentary condition compared to the active (P ≤ 0.05). Subjective feelings of hunger were not different between conditions at any point. Sedentary screen time was associated with significantly decreased response inhibition and a reversed brain activation pattern to pictures of high- and low-calorie foods compared to active play, in areas of the brain important to the modulation of food intake. Decreased attention, and impulse control following sedentary screen time may contribute to disinhibited eating that can lead to overweight and obesity.

Limited Agreement between Classifications of Diabetes and Prediabetes Resulting from the OGTT, Hemoglobin A1c, and Fasting Glucose Tests in 7412 U.S. Adults

This investigation was designed to determine the degree of concordance resulting from tests of fasting plasma glucose (FPG) and hemoglobin A1c (A1c) compared to the oral glucose tolerance test (OGTT) for detecting prediabetes and diabetes in undiagnosed adults. Another objective was to measure concordance within subsamples of women and men, and within three age groups. Lastly, the value of combining the FPG and A1c for detecting diabetes was compared to the OGTT. A total of 7412 randomly selected adults from the National Health and Nutrition Examination Survey (NHANES) were included. With outcomes classified as normal, prediabetes, or diabetes, according to standard guidelines, overall test agreements were low. With an OGTT diagnosis of diabetes, concordance was only 34% for the A1c assessment and 44% for the FPG assay. Delimited to older adults, agreement between the OGTT and A1c was only 25%, and between the OGTT and FPG, concordance was only 33.5%. Given the large percentage of discordant results associated with the FPG and A1c, clinicians should be cautious about employing these tests as lone assessments. Using both the FPG and A1c helped with accurately diagnosing diabetes and normal glycemia, but not prediabetes. The OGTT is a good choice to reduce misdiagnosis.

Walking and biologic ageing: Evidence based on NHANES telomere data

The length of telomeres is an objective measure of biologic ageing. This study evaluated the extent minutes of walking per week are associated with leukocyte telomere length (LTL) in a random sample of 5,823 U.S. adults. The investigation was cross-sectional and data were obtained from the National Health and Nutrition Examination Survey (NHANES). LTL was measured by the quantitative polymerase chain reaction method. Walking minutes was calculated from walking frequency and duration measures. Results showed that for each year of chronological age, telomeres were 15.6 base pairs shorter (P < 0.0001). With walking minutes and LTL treated as continuous variables, the relationship was quadratic, not linear (F = 11.2, P = 0.0023). With walking time divided into three categories, adults who performed ≥ 150 minutes of walking per week had longer telomeres than those who did no regular walking, and those who did some, but less than the recommendation (F = 5.0, P = 0.0137). Regular walkers were estimated to have a biologic ageing advantage associated with 6.5-7.6 years less biologic ageing compared to non-walkers, after adjusting for covariates. Additional investigations designed to study causality and the mechanisms associated with the walking and LTL relationship are needed.

Strength Training and Insulin Resistance: The Mediating Role of Body Composition

The main objective of the present study was to assess the association between participation in strength training and insulin resistance. Another goal was to assess the influence of several potential confounding variables on the strength training and insulin resistance relationship. Lastly, the influence of waist circumference, fat-free mass (kg), body fat percentage, and the fat-free mass index on the association between strength training and insulin resistance was assessed. This cross-sectional study included 6,561 randomly selected men and women in the U.S. Data were collected using the precise protocol established by NHANES. HOMA-IR was used as the outcome variable to index insulin resistance. Both time spent strength training and frequency of strength training bouts were used as exposure variables. There was not a statistically significant relationship between strength training and insulin resistance in women. However, before and after controlling for 11 potential confounding variables, men who reported no strength training had significantly higher levels of HOMA-IR compared to men who reported moderate or high levels of strength training (F = 9.87, P < 0.0001). Odds ratios were also assessed. Men reporting no strength training had 2.42 times the odds of having insulin resistance compared to men reporting moderate levels of strength training (95% CI: 1.19-4.93). Similarly, men reporting no strength training had 2.50 times the odds of having insulin resistance compared to men reporting high levels of strength training (95% CI: 1.25-5.00). In conclusion, there was a strong relationship between strength training and insulin resistance in U.S. men, but not in U.S. women. Differences in waist circumference, fat-free mass (kg), body fat percentage, and the fat-free mass index, as well as demographic and lifestyle measures, do not appear to mediate the relationship. The present study was not a clinical trial.

Physical Activity and Insulin Resistance in 6,500 NHANES Adults: The Role of Abdominal Obesity

This cross-sectional investigation studied differences in insulin resistance across levels of physical activity in 6,500 US adults who were randomly selected as part of the National Health and Nutrition Examination Survey (NHANES). Another important objective was to determine the influence of abdominal obesity on the physical activity and insulin resistance relationship. MET-minutes were utilized to quantify total activity based on participation in 48 different physical activities. Two strategies were employed to categorize levels of physical activity: one was based on relative MET-minutes (quartiles), and the other approach was based on the US physical activity guidelines. Insulin resistance was indexed using the homeostatic model assessment (HOMA). Abdominal obesity was indexed using waist circumference. Effect modification was tested by dividing waist circumferences into sex-specific quartiles and then evaluating the relationship between physical activity and HOMA-IR within each quartile separately. Results showed that relative physical activity level was associated with HOMA-IR after controlling for demographic and demographic and lifestyle covariates (F = 11.5, P < 0.0001 and F = 6.0, P=0.0012, respectively). Adjusting for demographic and demographic and lifestyle covariates also resulted in significant relationships between guideline-based activity and HOMA-IR (F = 8.0, P < 0.0001 and F = 4.9, P=0.0017, respectively). However, statistically controlling for differences in waist circumference with the other covariates nullified the relationship between total physical activity and HOMA-IR. Effect modification testing showed that when the sample was delimited to adults with abdominal obesity (Quartile 4), relative (F = 5.6, P=0.0019) and guideline-based physical activity (F = 3.7, P=0.0098) and HOMA-IR were significantly associated. Physical activity and HOMA-IR were not related within the other three quartiles. In conclusion, it appears that differences in physical activity may play a meaningful role in insulin resistance in those with abdominal obesity, but total activity does not seem to account for differences in insulin resistance among US adults with smaller waists.

The Impact of Step Recommendations on Body Composition and Physical Activity Patterns in College Freshman Women: A Randomized Trial

PURPOSE

Transitioning from high school to college generally results in reduced physical activity and weight gain at a rate that is higher than the general population. The purpose of this study was to examine the effects of three progressively higher step recommendations over 24 weeks on changes in body weight and body composition.

METHODS

Ninety-two freshmen college women wore a multifunction pedometer for 24 weeks after being randomly assigned to a daily step level: 10,000, 12,500, or 15,000. Pedometer data were downloaded every two weeks and participants were counseled on meeting their step recommendation. Body weight and body composition were assessed at baseline and 24 weeks. Body composition was assessed by dual X-ray absorptiometry.

RESULTS

On average, women took 10,786 ± 1501, 12,650 ± 2001, and 13,762 ± 2098 steps per day for the 10,000-, 12,500-, and 15,000-step groups, respectively (F = 15.48, P < 0.0001). Participants gained 1.4 ± 2.6, 1.8 ± 2.1, and 1.4 ± 2.1 kg for the 10,000-, 12,500-, and 15,000-step groups, respectively (F = 37.74, P < 0.0001). Weight gain was not significantly different between groups (F = 0.18, P=0.8385). There was also no difference in fat weight gain (F = 0.41, P=0.7954).

DISCUSSION

A step recommendation beyond 10,000 does not prevent weight or fat gain over the first year of college. Future research should focus on either intensity of physical activity or the addition of dietary interventions to prevent weight gain during the first year of college.

Sagittal Abdominal Diameter, Waist Circumference, and BMI as Predictors of Multiple Measures of Glucose Metabolism: An NHANES Investigation of US Adults

The objective was to compare associations between sagittal abdominal diameter (SAD), waist circumference, and BMI to the oral glucose tolerance test (OGTT), along with fasting glucose, HbA1c, and HOMA-IR, in a nationally representative sample of 3582 US adults. The study also analyzed the effect of multiple covariates on the anthropometric and glucose metabolism associations. A cross-sectional design was used. SAD was assessed using an abdominal caliper. All other data were collected following strict NHANES protocols. The OGTT was the primary variable used to index glucose metabolism. Fasting glucose, HbA1c, and HOMA-IR were also evaluated. Results showed that mean ± SE values were as follows: SAD: 22.3 ± 0.1 cm, waist circumference: 98.0 ± 0.4 cm, BMI: 28.6 ± 0.2 kg/m2, OGTT: 113.9 ± 1.0 mg/dL, fasting glucose: 99.6 ± 0.3 mg/dL, HbA1c: 5.4 ± 0.01%, and HOMA-IR: 3.2 ± 0.1. Compared to waist circumference and BMI, SAD consistently emerged as the best predictor of glucose metabolism, before and after adjusting for the covariates, and with the sample stratified by gender, race, or age. SAD was not a better predictor of OGTT among normal-weight adults or non-Hispanic Black adults. Due to the ease of taking SAD measurements, we recommend that healthcare providers use this simple method to more precisely predict diabetes risk, especially among overweight and obese adults.

Fiber Intake and Insulin Resistance in 6374 Adults: The Role of Abdominal Obesity

A cross-sectional design was used to evaluate the relationship between fiber intake and insulin resistance, indexed using HOMA (homeostatic model assessment), in a National Health and Nutrition Examination Study (NHANES) sample of 6374 U.S. adults. Another purpose was to test the influence of covariates on the association. A third aim was to compare HOMA levels between two groups based on the recommended intake of 14 grams of fiber per 1000 kilocalories (kcal). Fiber intake was measured using a 24-hour recall. With demographic variables controlled, results showed that HOMA differed across High, Moderate, and Low fiber categories (F = 5.4, p = 0.0072). Adjusting for the demographic variables, the possible misreporting of energy intake, smoking, and physical activity strengthened the relationship (F = 8.0, p = 0.0009), which remained significant after adjusting for body fat (F = 7.0, p = 0.0019) and body mass index (BMI) (F = 4.9, p = 0.0108), with the other covariates. However, the fiber-HOMA relationship was eliminated after adjusting for waist circumference (F = 2.3, p = 0.1050). Dividing participants based on the recommended 14-gram standard resulted in meaningful HOMA differences (F = 16.4, p = 0.0002), and the association was not eliminated after controlling for waist circumference. Apparently, adults with high fiber consumption have less insulin resistance than their counterparts. However, much of the association is due to differences in waist circumference, unless the recommended intake of fiber is attained.

Physical activity and telomere length in U.S. men and women: An NHANES investigation

The principal objective was to determine the extent to which physical activity (PA) accounts for differences in leukocyte telomere length (LTL) in a large random sample of U.S. adults. Another purpose was to assess the extent to which multiple demographic and lifestyle covariates affect the relationship between PA and LTL. A total of 5823 adults from the National Health and Nutrition Examination Survey (NHANES 1999-2002) were studied cross-sectionally. Employing the quantitative polymerase chain reaction method, LTL was compared to standard reference DNA. PA was indexed using MET-minutes using self-reported frequency, intensity, and duration of participation in 62 physical activities. Covariates were controlled statistically. Telomeres were 15.6 base pairs shorter for each year of chronological age (F=723.2, P<0.0001). PA was inversely related to LTL after adjusting for all the covariates (F=8.3, P=0.0004). Telomere base pair differences between adults with High activity and those in the Sedentary, Low, and Moderate groups were 140, 137, and 111, respectively. Adults with High activity were estimated to have a biologic aging advantage of 9years (140 base pairs÷15.6) over Sedentary adults. The difference in cell aging between those with High and Low activity was also significant, 8.8years, as was the difference between those with High and Moderate PA (7.1years). Overall, PA was significantly and meaningfully associated with telomere length in U.S. men and women. Evidently, adults who participate in high levels of PA tend to have longer telomeres, accounting for years of reduced cellular aging compared to their more sedentary counterparts.

Alpha- and Gamma-Tocopherol and Telomere Length in 5768 US Men and Women: A NHANES Study

Antioxidants have a number of potential health benefits. The present investigation was designed to determine the relationship between serum alpha- and gamma-tocopherol levels (powerful antioxidants), and leukocyte telomere length (a biomarker of biological aging). A cross-sectional design was employed to study 5768 adults from the National Health and Nutrition Examination Survey (NHANES). DNA was obtained via blood samples. Telomere length was assessed using the quantitative polymerase chain reaction method. Serum concentrations of alpha- and gamma-tocopherol were measured using high performance liquid chromatography (HPLC). Results showed that for each one-year increase in age, telomeres were 15.6 base pairs shorter (F = 410.4, p < 0.0001). After adjusting for differences in the demographic covariates, for each µg/dL higher level of gamma-tocopherol, telomeres were 0.33 base pairs shorter (F = 7.1, p = 0.0126). Telomeres were approximately 1 year shorter (15.6 base pairs) for each increment of 47.3 to 55.7 µg/dL of gamma-tocopherol in the blood, depending on the variables controlled. Adults at the 75th percentile of gamma-tocopherol had 2.8–3.4 years greater cellular aging than those at the 25th percentile, depending on the covariates in the model. However, alpha-tocopherol was not related to telomere length. Evidently, gamma-tocopherol levels, but not alpha-tocopherol, account for meaningful increases in biological aging.

Strength training and body composition in middle-age women

BACKGROUND

Strength training is a sound method to improve body composition. However, the effect of age, diet, menopause, and physical activity on the relationship between strength training and body composition in women remains unknown. The purpose of this study was to examine the intricacies of the relationship between strength training and body composition in 257 middle-age women and to quantify the effect of these factors on the association.

METHODS

The study was cross-sectional. Five variables were used to index strength training participation. Body composition was assessed by dual-energy X-ray absorptiometry. Diet was assessed by 7-day weighed food records, and physical activity was measured objectively using accelerometers.

RESULTS

There were 109 strength trainers in the sample. For each day per week of strength training, body fat was 1.3 percentage points lower (F=14.8, P<0.001) and fat-free mass was 656 g higher (F=18.9, P<0.001). Likewise, the more time women spent lifting and the more intensely they trained, the better their body composition tended to be. Differences in age, energy and protein consumption had little effect on the associations. However, adjusting for differences in physical activity, and to a lesser extent, menopause status, weakened the relationships significantly.

CONCLUSIONS

The more days, time, and effort women devote to strength training, the lower their body fat and the higher their fat-free mass tend to be. A significant portion of the differences in body composition seems to result from lifters participating in more physical activity than non-lifters. Menopause status also contributes significantly to the relationship.

Disparity in neural and subjective responses to food images in women with obesity and normal-weight women

OBJECTIVE

Self-reports tend to differ from objective measurements of food intake, particularly in adults with obesity; however, no studies have examined how neural responses to food (an objective measure) and subjective ratings of food differ by BMI status. This study tested normal-weight women (NWW) and women with obesity (OBW) for group differences in neural indices of attention towards food pictures, subjective ratings of these pictures, and the disparity between objective and subjective measurements.

METHODS

Twenty-two NWW (21.8 ± 1.7 kg/m² ) and 22 OBW (37.0 ± 5.7 kg/m² ) viewed food and flower pictures while late positive potential amplitude, an event-related potential, was recorded. Participants rated pictures for arousal and valence.

RESULTS

Late positive potential amplitude was larger toward food than flower pictures. OBW self-reported flower pictures as more pleasant than food; NWW showed no difference for pleasantness. There were no significant main effects or interactions for arousal. Standardized scores showed that only on subjective, but not objective, measures did OBW compared with NWW disproportionately indicate food pictures as less pleasant than flowers.

CONCLUSIONS

Compared with NWW, OBW showed larger discrepancies between neural and subjective reports of attention towards food. Inaccurate self-reports of attention towards food may reduce the efficiency of health interventions.

Caffeine consumption and telomere length in men and women of the National Health and Nutrition Examination Survey (NHANES)

BACKGROUND

The investigation evaluated the relationship between caffeine intake and coffee consumption and leukocyte telomere length, a biomarker of the senescence of cells.

METHODS

A total of 5826 adults from the National Health and Nutrition Examination Survey (NHANES) were studied cross-sectionally. Using the quantitative polymerase chain reaction method, telomere length was compared to standard reference DNA. Caffeine intake from foods and beverages and coffee consumption were measured using a validated, multi-pass, computer-assisted, 24-h recall system administered by NHANES interviewers. The following covariates were controlled: age, gender, race, marital status, education, housing, smoking, BMI, physical activity, alcohol use, and coffee intake (or caffeine consumption).

RESULTS

Caffeine consumption was inversely related to telomere length (F = 15.1, P = 0.0005). For each 100 mg of caffeine consumed, telomeres were 35.4 base pairs shorter, after adjusting for the covariates. For each 100 mg of caffeine consumed among coffee drinkers only, telomeres were 36.7 base pairs shorter (F = 9.0, P = 0.0054), and among non-coffee drinkers only, 40.0 base pairs shorter (F = 8.5, P = 0.0067). Conversely, coffee intake was positively related to telomere length (F = 12.6, P = 0.0013), independent of the covariates.

CONCLUSIONS

Results suggest that caffeine consumption accounts for shorter telomeres in U.S. adults, independent of numerous covariates, whereas coffee intake predicts longer telomeres.

Expanded Normal Weight Obesity and Insulin Resistance in US Adults of the National Health and Nutrition Examination Survey

This study aims to expand the evaluation of normal weight obesity (NWO) and its association with insulin resistance using an NHANES (1999-2006) sample of US adults. A cross-sectional study including 5983 men and women (50.8%) was conducted. Body fat percentage (BF%) was assessed using dual-energy X-ray absorptiometry. Expanded normal weight obesity (eNWO) categories, pairings of BMI and body fat percentage classifications, were created using standard cut-points for BMI and sex-specific median for BF%. Homeostatic model assessment-insulin resistance (HOMA-IR) levels were used to index insulin resistance. Mean ± SE values were BMI: 27.9 ± 0.2 (women) and 27.8 ± 0.1 (men); body fat percentage: 40.5 ± 0.2 (women) and 27.8 ± 0.2 (men); and HOMA-IR: 2.04 ± 0.05 (women) and 2.47 ± 0.09 (men). HOMA-IR differed systematically and in a dose-response fashion across all levels of the eNWO categories (F = 291.3, P < 0.0001). As BMI levels increased, HOMA-IR increased significantly, and within each BMI category, higher levels of body fat were associated with higher levels of HOMA-IR. Both high BMI and high BF% were strongly related to insulin resistance. Insulin resistance appears to increase incrementally according to BMI levels primarily and body fat levels secondarily. Including a precise measure of body fat with BMI adds little to the utility of BMI in the prediction of insulin resistance.

Consumption of Nuts and Seeds and Telomere Length in 5,582 Men and Women of the National Health and Nutrition Examination Survey (NHANES)

OBJECTIVES

Consumption of nuts and seeds is associated favorably with all-cause mortality. Nuts and seeds could reduce disease and prolong life by influencing telomeres. Telomere length is a good indicator of the senescence of cells. The purpose of the present study was to determine the relationship between nuts and seeds intake and leukocyte telomere length, a biomarker of biologic aging.

DESIGN

Cross-sectional.

SETTING AND PARTICIPANTS

A total of 5,582 randomly selected men and women from the National Health and Nutrition Examination Survey (NHANES), 1999-2002, were studied.

MEASUREMENTS

DNA was obtained via blood samples. Telomere length was assessed using the quantitative polymerase chain reaction method. A validated, multi-pass, 24-h recall dietary assessment, administered by NHANES, was employed to quantify consumption of nuts and seeds.

RESULTS

Nuts and seeds intake was positively and linearly associated with telomere length. For each 1-percent of total energy derived from nuts and seeds, telomere length was 5 base pairs longer (F=8.6, P=0.0065). Given the age-related rate of telomere shortening was 15.4 base pairs per year (F=581.1, P<0.0001), adults of the same age had more than 1.5 years of reduced cell aging if they consumed 5% of their total energy from nuts and seeds.

CONCLUSIONS

Consumption of nuts and seeds accounts for meaningful decreases in biologic aging and cell senescence. The findings reinforce the recommendations of the 2015-2020 Dietary Guidelines for Americans, which encourage the consumption of nuts and seeds as part of a healthy diet.

Effect of two jumping programs on hip bone mineral density in premenopausal women: a randomized controlled trial

PURPOSE

To determine the effect of two jumping programs on hip bone mineral density (BMD) in women.

DESIGN

Randomized controlled trial.

SETTING

Approximately 20 cities in the Mountain West.

SUBJECTS

Sixty premenopausal women, aged 25 to 50 years, completed the intervention.

INTERVENTION

Subjects were randomly assigned to a control group or one of two jumping groups. The Jump 10 group performed 10 jumps with 30 seconds rest between jumps, twice daily for 16 weeks, while the Jump 20 group performed the same protocol but with 20 jumps.

MEASURES

Hip BMD was measured by using dual-energy x-ray absorptiometry.

ANALYSIS

Analysis of variance and covariance.

RESULTS

At 8 weeks, unadjusted percentage change in hip BMD was significantly different among groups (F = 5.4, p = .0236). Specifically, compared with controls, the Jump 20 women had significantly greater gains in hip BMD and the Jump 10 women had marginally greater improvements. Following 16 weeks of jumping, differences between the Jump 10 and the Jump 20 groups compared with controls were significant (F = 4.2, p = .0444), especially after adjusting for the covariates (F = 7.3, p = .0092).

CONCLUSION

After 16 weeks of high-impact jump training, hip BMD can be improved in premenopausal women by jumping 10 or 20 times, twice daily, with 30 seconds of rest between each jump, compared with controls.

Internal Structure, Factor Satisfaction, and Reliability of the Body Cathexis Scale

The primary purpose of this study was to examine the internal structure and dimensionality of the Body Cathexis Scale, while secondary problems were to compare the relative satisfaction of each factor and to determine the test-retest reliability of the instrument. The scale was administered on a pretest-posttest basis to a sample of 83 college males. Using a factor analytic strategy with varimax rotation, four independent factors emerged: (1) Health and Physical Fitness, (2) Face and Over-all Appearance, (3) Subordinate and Independent Body Features, and (4) Physique and Muscular Strength. Analysis of the relative satisfaction reported for each axis indicated significant differences among the factors. The items of the first two factors were rated significantly more favorably than the variables of the second two dimensions. Test-retest reliability coefficient was .87, suggesting that the Body Cathexis Scale is stable over time.

Weight Training Experience and Psychological Well-Being

The Tennessee Self-concept Scale, Body Cathexis Scale, and Eysenck Personality Inventory were administered to 113 university males who were also asked to report the total number of months they had trained with weights in the past. Analysis showed that as weight-training experience increased, measures of self-concept, body satisfaction, and extraversion increased commensurately and lie-scale scores decreased proportionately.

Fitness and bone density in women: the role of age, weight, calcium, vitamin D, and menopause

BACKGROUND

The purpose of the present study was to evaluate the relationship between manifold measures of fitness and bone mineral density (BMD) of the hip and spine in 233 middle-aged women. An additional objective was to determine the effect of several potential confounding variables, including age, body weight, calcium consumption, vitamin D intake, and menopause status on the relationships between fitness and BMD.

METHODS

A cross-sectional design was used. Fitness was indexed using multiple variables: bench press, sit-ups, best jump, VO2max, and total fitness. Total fitness was indexed using the mean Z-score of the other fitness tests. Hip and spine BMD were assessed using dual energy X-ray absorptiometry.

RESULTS

The associations between hip BMD and bench press (F=5.3, P=0.0219), sit-up (F=7.5, P=0.0065), best jump (F=11.6, P=0.0008), VO2max (F=9.3, P=0.0025), and Total Fitness (F=16.1, P≤0.0001) were statistically significant. Relationships between spine BMD and four of the dimensions of fitness were significant: bench press (F=9.4, P=0.0025), sit-up (F=11.7, P=0.0007), best jump (F=6.9, P=0.0093), and the composite fitness score (F=13.4, P=0.0003). VO2max was not predictive of spine BMD (F=2.0, P=0.1610). Age had the strongest confounding effect on the hip BMD associations, whereas menopause status had the strongest influence on the spine BMD relationships.

CONCLUSIONS

In conclusion, findings suggest that objectively measured fitness is a strong predictor of differences in BMD of the hip and spine in middle-aged women, before and after adjusting for differences in several potential confounding variables.

Reduced Sleep Acutely Influences Sedentary Behavior and Mood But Not Total Energy Intake in Normal-Weight and Obese Women

Using a crossover design, 22 normal-weight and 22 obese women completed two free-living sleep conditions: (a) Normal Sleep: night of ~8 hr time in bed; and (b) Reduced Sleep: night of < 5 hr time in bed). Outcome measures were energy intake, physical activity and sedentary time, and mood. Sleep time was 7.7 ± 0.3 and 4.8 ± 0.2 hrs during the Normal Sleep and Reduced Sleep conditions, respectively (F = 1791.94; p < 0.0001). Energy intake did not differ between groups or as a function of sleep condition (F = 2.46; p = 0.1244). Sedentary time was ~ 30 min higher after the Reduced Sleep condition (F = 4.98; p = 0.0318); other physical activity outcomes were not different by condition (p > 0.05). Total mood score, depression, anger, vigor, fatigue, and confusion were worse after Reduced Sleep (p < 0.05). Reducing sleep acutely and negatively influenced sedentary time and mood in normal-weight and obese women.

Predictors of Grades Assigned by Graduate Teaching Assistants in Physical Education

To determine possible predictors of grades assigned by graduate teaching assistants in physical education service programs, average grade assignments of 20 assistants for one quarter, collected over 2 yr., were compared with demographic data, teaching experience, GRE scores, total score on the Tennessee Self-concept Scale, and teachers' ratings. Bivariate correlations indicated that the average grade assigned by assistants was related significantly to sex, marital status, and global self-concept; however, age, teaching experience in public schools, total GRE scores, and students' ratings of teachers' effectiveness were not related significantly to the mean grades assigned to students.

Relationship between Perceived Somatotype and Body Cathexis of College Males

The primary purpose of this study was to determine if males grouped according to self-perceived somatotype differ significantly in body concept, while a subordinate purpose was to identify the perceived somatotype response trends of a college male population. The Perceived Somatotype Scale and the Body Cathexis Scale were administered to 88 male undergraduates, and the data were analyzed by multiple regression. The somatotype the males perceived as their own, and the body build perceived as ideal accounted for 27.9% and 4.3% of the variance in body-cathexis scores, respectively. A measure of discrepancy between the perceived somatotype-self and ideal indices accounted for 22.7% of the variance in the criterion. As self-perception of somatotype deviates from mesomorphic and moves toward the ectomorphic and endomorphic poles, especially the latter, self-concept relative to the body tends to decline rapidly. Moreover, males who perceive their physiques differ from their perceived ideals tend to report significantly less body satisfaction than those who perceive no such discrepancy.

Effect of a Weight-Training Program on the Self-Concepts of College Males

This study was conducted to determine the effect of a weight-training program on the self-concepts of 105 college males and whether or not success in the lifting program affected self-concepts. Subjects were randomly selected by a duster-sampling strategy, divided by self-selection into an experimental and a control group, and assessed on the Tennessee Self-concept Scale. The weight-training program required two intense 50-min. total-body workouts per week for 16 wk. Significant differences between groups were found on five of the nine self-concept measures including the Total Positive score; this supported the hypothesis that regular weight-training positively influences self-concept. The experimental group also showed significant improvement from pre- to posttest on eight of the nine self-concept indices, yet control subjects displayed no significant changes on any of the measures. Level of success in the lifting program was not determined to be a significant moderator variable.

A Prospective Study of Physical Activity Intensity and Change in Adiposity in Middle-Aged Women

Purpose.

To determine the extent to which objectively measured intensity of physical activity (PA) predicts change in body fat (BF%) in women.

Design.

Prospective cohort study of PA intensity and body composition in middle-aged women.

Setting.

The study took place in a metropolitan Mountain West community.

Subjects.

Two hundred and twenty-eight women participated in two assessment periods separated by 20 months.

Measures.

Each assessment period consisted of seven consecutive days of monitoring, followed by body composition testing.

Analysis.

The general linear model using partial correlations and Mantel-Haenszel χ2 tests were performed.

Results.

At baseline and follow-up, women who participated in vigorous PA were leaner than women who participated in moderate or light PA (p < .05). Longitudinal results indicated that a greater proportion of women who decreased PA intensity over the 20 months also increased BF% (66%), compared to participants who increased or maintained PA intensity (47%) (p < .05).

Conclusions.

PA intensity seems to play a role in long-term weight maintenance. Reducing PA intensity increases the risk of BF% gain in women. Efforts to help women maintain PA intensity along with other weight management strategies may prove beneficial in preventing unwanted body fat gain in middle-aged women.

Cardiovascular Fitness and Absenteeism in 8,301 Employed Adults

The purpose of this study was to determine the extent of the relationship between cardiovascular fitness and absenteeism in the workplace. A total of 8,301 adult males and females who were employed by corporations which participated in a health screening program were used in the study. Absenteeism due to illness, demographic variables, and smoking status were assessed using a written questionnaire, while body fat was measured using skinfold calipers and cardiovascular fitness was assessed using a step test. Results indicated that high levels of cardiovascular fitness were associated significantly with low levels of absenteeism. The relationship remained strong after adjusting for differences in age, gender, income, cigarette smoking, and percent body fat. The association was stronger in females than males.

Television Viewing Time and Measured Cardiorespiratory Fitness in Adult Women

Purpose.

This study assessed the relationship between television viewing time and measured cardiorespiratory fitness and the influence of various potential confounders.

Design.

Cross-sectional.

Setting.

Intermountain West.

Subjects.

The sample was composed of 302 nonsmoking women aged 40.2 ± 3.0 years, with ∼90% Caucasian and 82% married.

Measures.

TV viewing was assessed by using a questionnaire, and cardiorespiratory fitness was measured by using a graded, maximum treadmill test. Physical activity (PA) was evaluated by using accelerometers for 7 days, and body fat percentage (BF%) was measured by using the Bod Pod.

Analysis.

Analysis of variance and partial correlation.

Results.

VO2max of Frequent (≥3 h/d) TV viewers (32.6 ± 6.4 mL/kg/min) was significantly lower than that of both Moderate (1–2 h/d) (36.2 ± 7.2 mL/kg/min) or Infrequent (<1 h/d) (36.5 ± 6.5 mL/kg/min) viewers (F= 8.0, p = .0004). The Infrequent and Moderate groups did not differ in VO2max. Age, education, body mass index, and season of assessment had no influence on the relationship when controlled statistically. Adjusting for PA (F = 4.2, p = .0157) and BF% (F = 5.0, p = .0071) weakened the relationship by 59% and 58%, respectively, but the relationships remained significant. After controlling for both PA and BF% simultaneously (F = 2.9, p = .0572), the relationship was weakened by 81% and was only borderline significant.

Conclusion.

Female Frequent TV viewers have significantly lower cardiorespiratory fitness levels than Moderate or Infrequent viewers. This association appears to be largely a function of differences in levels of PA and BF%.

Dietary Patterns as Predictors of Body Fat and BMI in Women: A Factor Analytic Study

Purpose.

To identify independent patterns of diet using factor analysis to determine the extent to which dietary patterns account for differences in body fat percentage (BF%) and body mass index (BMI). Also, to ascertain the extent to which the associations are influenced by age, education, menopause, energy intake, and physical activity.

Design.

Study design was cross-sectional.

Setting.

Study setting was approximately 20 cities in the Mountain West.

Subjects.

The study included 281 apparently healthy female nonsmokers.

Measures.

Diet was assessed using 7-day weighed food records, and foods were categorized using the American Diabetes and American Dietetic Associations Exchange Lists and expressed as servings per 1000 kcal. BF% was measured using the Bod Pod, and physical activity was estimated using accelerometers worn for 1 week.

Analysis.

We used factor analysis, general linear models, and partial correlations.

Results.

Three dietary patterns were identified: (1) Prudent Pattern, (2) Low-fat Milk, and (3) Meat. Higher consumption of the Prudent Pattern corresponded with significantly lower BF% (F = 8.5, p = .0038) and BMI (F = 4.4, p = .0363). The Low-fat Milk pattern was inversely related to BF% (F= 5.4, p = .0207) and BMI (F= 9.5, p = .0023). Higher intake of the Meat pattern was related to higher levels of BF% (F= 4.5, p= .0346) and BMI (F= 4.2, p = .0418).

Conclusion.

These findings support an association between dietary patterns and body composition. Dietary patterns reflect the complex interrelationships inherent in day-to-day eating and are strongly related to differences in BF% and BMI in women.

Meat Intake and Insulin Resistance in Women without Type 2 Diabetes

PURPOSE

To examine the relationship between meat intake and insulin resistance (IR) in 292 nondiabetic women.

METHODS

IR was evaluated using the homeostasis model assessment (HOMA). Diet was assessed via 7-day weighed food records. Servings of very lean meat (VLM) and regular meat (meat) were indexed using the ADA Exchange Lists Program. Physical activity was assessed using accelerometers and body fat was measured using the Bod Pod.

RESULTS

Meat intake was directly related to HOMA (F = 7.4; P = 0.007). Women with moderate or high meat intakes had significantly higher HOMA levels than their counterparts. Adjusting for body fat weakened the relationship (F = 1.0; P = 0.3201). Odds ratio results showed that the low meat quartile had 67% lower odds of being IR (75th percentile) compared to their counterparts (OR = 0.33; 95% CI = 0.16-0.71). These findings changed little after adjusting for all covariates simultaneously (OR = 0.34; 95% CI = 0.14-0.83). Conversely, VLM intake was not related to HOMA, with or without the covariates.

CONCLUSION

Moderate and high meat intakes are associated with increased insulin resistance in nondiabetic women. However, differences in body fat contribute significantly to the relationship. VLM is not predictive of IR. Prudence in the amount and type of meat consumed may be helpful in decreasing the likelihood of IR.

Dairy consumption and insulin resistance: the role of body fat, physical activity, and energy intake

The relationship between dairy consumption and insulin resistance was ascertained in 272 middle-aged, nondiabetic women using a cross-sectional design. Participants kept 7-day, weighed food records to report their diets, including dairy intake. Insulin resistance was assessed using the homeostatic model assessment (HOMA). The Bod Pod was used to measure body fat percentage, and accelerometry for 7 days was used to objectively index physical activity. Regression analysis was used to determine the extent to which mean HOMA levels differed across low, moderate, and high dairy intake categories. Results showed that women in the highest quartile of dairy consumption had significantly greater log-transformed HOMA values (0.41 ± 0.53) than those in the middle-two quartiles (0.22 ± 0.55) or the lowest quartile (0.19 ± 0.58) (F = 6.90, P = 0.0091). The association remained significant after controlling for each potential confounder individually and all covariates simultaneously. Adjusting for differences in energy intake weakened the relationship most, but the association remained significant. Of the 11 potential confounders, only protein intake differed significantly across the dairy categories, with those consuming high dairy also consuming more total protein than their counterparts. Apparently, high dairy intake is a significant predictor of insulin resistance in middle-aged, nondiabetic women.

Adherence to the 2010 Dietary Guidelines for Americans and the relationship to adiposity in young women

OBJECTIVE

To determine the relationship between adherence to the 2010 Dietary Guidelines for Americans and adiposity in young women with and without statistical adjustment for physical activity (PA).

METHODS

Participants included 324 young women (aged 17-25 years). The researchers measured dietary intake using the Dietary History Questionnaire and determined diet quality using the 2010 Healthy Eating Index (HEI-2010). BOD POD (Cosmed, Rome, Italy, 2006) and accelerometry were used to assess body fat and PA, respectively.

RESULTS

Women in the top quartile of HEI-2010 had significantly lower percent body fat than women in the lowest 3 quartiles (F = 3.36; P = .03). Controlling for objectively measured PA weakened this relationship by 20%. These young women (top quartile of HEI-2010) also had 0.37 odds (95% confidence interval, 0.16-0.85) of having body fat > 32%.

CONCLUSIONS AND IMPLICATIONS

Young women whose diets most closely meet the 2010 Dietary Guidelines for Americans have lower adiposity.

Cardiorespiratory Fitness and Hip Bone Mineral Density in Women: A 6-Year Prospective Study

Cross-sectional studies and short term interventions focusing on fitness and bone mineral density (BMD) are common. However, few investigations have studied the effect of fitness on BMD over an extended period of time. The present study was conducted to determine the extent to which cardiorespiratory fitness influences risk of BMD loss at the hip over 6 yr. A prospective cohort design was used with 245 healthy, middle-aged women. Hip BMD was assessed using dual energy x-ray absorptiometry. Calcium and vitamin D were measured using the Block Food Frequency Questionnaire. Menopause status was measured by a questionnaire. Results showed that fit and unfit women experienced similar changes in hip BMD over time. Specifically, unfit women experienced a non-significant 7% increased risk of losing hip BMD compared to their counterparts (RR = 1.07, 95% CI = 0.66, 1.73). Adjusting statistically for differences in age, initial body weight, and hip BMD, weight change, menopause status, calcium and vitamin D intake, and time between assessments had little effect on the relationship. Fitness level did not influence risk of hip BMD loss over time.