Total daily energy expenditure in free-living older African-Americans and Caucasians

Dietary intake of polish organic and conventional fruit growers and their life partners - a pilot study

Diet is one of the elements that contribute to health and quality of life. There are significant discrepancies between the diets of people living in different regions, with different beliefs, or with different approaches to sustainability and ecology. There is a lack of research on dietary intake among organic and conventional fruit growers. The aim of our study was to examine the diets of orchardists and their immediate life partners in terms of meeting energy requirements, nutrient intake and fulfillment of dietary recommendations in this group. Fifty-three participants (28 in the organic group and 25 in the conventional group) took part in the study. Dietary data were obtained using the 3-day dietary record. Body mass and height were measured and BMI was calculated. Physical activity was estimated using a questionnaire method. The study group was aged 44 ± 8 years, with a body weight of 84 ± 16 kg and a height of 172 ± 9 cm. The mean BMI was 28 ± 4 kg/m2. Mean energy intake with diet was 2170 ± 606 kcal/day with needs of 3002 (1991-5144) kcal/day. A significant proportion of the study group did not fulfill their calcium and vitamin D requirements. In addition, a significant proportion of the conventional fruit growers did not cover their needs for potassium, magnesium and vitamins: E, C, and folate. Both groups had too high an intake of cholesterol and saturated fatty acids, and too low an intake of polyunsaturated fatty acids. In conclusion, the orchardists' diets mostly provided adequate amounts of nutrients, with inadequate intakes of calcium, vitamin D, cholesterol, and fatty acids. The diets of organic fruit growers were significantly richer in selected nutrients.

Racial Variations in Appetite-Related Hormones, Appetite, and Laboratory-Based Energy Intake from the E-MECHANIC Randomized Clinical Trial

African Americans (AAs) have a higher obesity risk than Whites; however, it is unclear if appetite-related hormones and food intake are implicated. We examined differences in appetite-related hormones, appetite, and food intake between AAs (n = 53) and Whites (n = 111) with overweight or obesity. Participants were randomized into a control group or into supervised, controlled exercise groups at 8 kcal/kg of body weight/week (KKW) or 20 KKW. Participants consumed lunch and dinner at baseline and follow-up, with appetite and hormones measured before and after meals (except leptin). At baseline, AAs had lower peptide YY (PYY; p < 0.01) and a blunted elevation in PYY after lunch (p = 0.01), as well as lower ghrelin (p = 0.02) and higher leptin (p < 0.01) compared to Whites. Despite desire to eat being lower and satisfaction being higher in AAs relative to Whites (p ≤ 0.03), no racial differences in food intake were observed. Compared to Whites, leptin increased in the 8 KKW group in AAs (p = 0.01), yet no other race-by-group interactions were evident. Differences in appetite-related hormones between AAs and Whites exist; however, their influence on racial disparities in appetite, food intake, and obesity within this trial was limited.

Total energy expenditure is comparable between patients with and without diabetes mellitus: Clinical Evaluation of Energy Requirements in Patients with Diabetes Mellitus (CLEVER-DM) Study

OBJECTIVE

Assessment of total energy expenditure (TEE) is essential for appropriate recommendations regarding dietary intake and physical activity in patients with and without diabetes mellitus (DM). However, few reports have focused on TEE in patients with DM, particularly in Asian countries. Therefore, we evaluated TEE in Japanese patients with DM using the doubly labeled water (DLW) method and physical activity level (PAL).

RESEARCH DESIGN AND METHODS

In this cross-sectional observational study, we evaluated 52 patients with type 2 DM and 15 patients without DM. Free-living TEE was measured over 12-16 days by the DLW method, and PAL was calculated as TEE divided by the basal metabolic rate (BMR) as assessed by indirect calorimetry. The equivalence margin was defined as 5 kcal/kg/day.

RESULTS

The numbers of patients with DM treated with insulin, oral antidiabetic drugs, and diet were 18 (34.6%), 20 (38.5%), and 14 (26.9%), respectively. The mean±SD level of glycated hemoglobin was 6.9%±0.8% and 5.5%±0.3% in the DM and non-DM group, respectively (p<0.001). The mean body mass index was 23.3±3.0 and 22.7±2.1 kg/m² in the DM and non-DM group, respectively. The mean TEE per kilogram body weight adjusted for sex and age was 36.5 kcal/kg/day and 37.5 kcal/kg/day in the DM and non-DM group, respectively, with no significant difference (mean difference, -1.0 kcal/kg/day; 95% CI -4.2 to 2.3 kcal/kg/day). The BMR tended to be higher in the DM than in the non-DM group (mean difference, 33 kcal/day; 95% CI, -15 to 80 kcal/day). The mean PAL adjusted for sex and age was 1.71 and 1.81 in the DM and non-DM group, respectively, without a significant difference (mean difference, -0.10; 95% CI -0.21 to 0.01).

CONCLUSION

TEE was comparable between Japanese patients with and without DM.

TRIAL REGISTRATION NUMBER

UMIN000023051.

Mitochondrial Respiration is Associated with Lower Energy Expenditure and Lower Aerobic Capacity in African American Women

OBJECTIVE

Reasons for the higher obesity prevalence in African American women (AAW) compared with Caucasian women (CW) are unknown. Energy expenditure and maximal aerobic capacity (VO₂ max) are lower in AAW. It was hypothesized that these differences are explained by skeletal muscle characteristics, particularly mitochondrial content and function.

METHODS

Multivariate regression analyses were used to examine the relationships between energy expenditure (resting and during a hyperinsulinemic-euglycemic clamp) and VO₂ max versus body composition, physical activity, and skeletal muscle mitochondrial measurements in AAW and CW.

RESULTS

In AAW, VO₂ max was lower (P < 0.0001). Body-composition-adjusted energy expenditure during the clamp was lower in AAW (P < 0.002). Physical activity was similar in both groups. After adjusting for mitochondrial respiration, racial differences in energy expenditure and VO₂ max were no longer present. Another novel finding was that a thermogenic response to the clamp was observed in CW (+53 ± 22 kcal/d; P < 0.03) but not in AAW (-19 ± 24 kcal/d; P = 0.43).

CONCLUSIONS

AAW and CW show differences in adjusted energy expenditure and aerobic capacity that are largely accounted for by differences in skeletal muscle mitochondrial oxidative characteristics. Further research is needed to determine whether lower mitochondrial respiration and lower thermogenesis are risk factors for obesity in AAW.

Validation of dietary reference intake equations for estimating energy requirements in Korean adults by using the doubly labeled water method

BACKGROUND/OBJECTIVES

The doubly labeled water (DLW) method is considered the gold standard for the measurement of total energy expenditure (TEE), which serves to estimate energy requirements. This study evaluated the accuracy of predictive dietary reference intake (DRI) equations for determining the estimated energy requirements (EER) of Korean adults by using the DLW as a reference method.

SUBJECTS/METHODS

Seventy-one participants (35 men and 36 women) aged between 20 and 49 years were included in the study. The subjects' EER, calculated by using the DRI equation (EER_DRI), was compared with their TEE measured by the DLW method (TEE_DLW).

RESULTS

The DRI equations for EER underestimated TEE by -36.3 kcal/day (-1.3%) in men and -104.5 kcal/day (-4.9%) in women. The percentages of accurate predictions among subjects were 77.1% in men and 62.9% in women. There was a strong linear correlation between EER_DRI and TEE_DLW (r=0.783, P<0.001 in men and r=0.810, P<0.001 in women).

CONCLUSIONS

The present study supports the use of DRI prediction equations to determine EER in Korean adults. More studies are needed to confirm our results and to assess the validity of these equations in other population groups, including children, adolescents, and older adults.

Endothelial Cell Bioenergetics and Mitochondrial DNA Damage Differ in Humans Having African or West Eurasian Maternal Ancestry

BACKGROUND

We hypothesized that endothelial cells having distinct mitochondrial genetic backgrounds would show variation in mitochondrial function and oxidative stress markers concordant with known differential cardiovascular disease susceptibilities. To test this hypothesis, mitochondrial bioenergetics were determined in endothelial cells from healthy individuals with African versus European maternal ancestries.

METHODS AND RESULTS

Bioenergetics and mitochondrial DNA (mtDNA) damage were assessed in single-donor human umbilical vein endothelial cells belonging to mtDNA haplogroups H and L, representing West Eurasian and African maternal ancestries, respectively. Human umbilical vein endothelial cells from haplogroup L used less oxygen for ATP production and had increased levels of mtDNA damage compared with those in haplogroup H. Differences in bioenergetic capacity were also observed in that human umbilical vein endothelial cells belonging to haplogroup L had decreased maximal bioenergetic capacities compared with haplogroup H. Analysis of peripheral blood mononuclear cells from age-matched healthy controls with West Eurasian or African maternal ancestries showed that haplogroups sharing an A to G mtDNA mutation at nucleotide pair 10398 had increased mtDNA damage compared with those lacking this mutation. Further study of angiographically proven patients with coronary artery disease and age-matched healthy controls revealed that mtDNA damage was associated with vascular function and remodeling and that age of disease onset was later in individuals from haplogroups lacking the A to G mutation at nucleotide pair 10398.

CONCLUSIONS

Differences in mitochondrial bioenergetics and mtDNA damage associated with maternal ancestry may contribute to endothelial dysfunction and vascular disease.

Racial/Ethnic Differences in Insulin Resistance and Beta Cell Function: Relationship to Racial Disparities in Type 2 Diabetes among African Americans versus Caucasians

Both biological and sociocultural factors have been implicated in the well-documented racial disparity in incidence and prevalence of type 2 diabetes (T2D) between African Americans (AA) and non-Hispanic whites (NHW). This review examines the extent to which biological differences in glucose metabolism, specifically insulin resistance and beta cell function (BCF), contribute to this disparity. The majority of available data suggests that AA are more insulin resistant and have upregulated BCF compared to NHW. Increasing evidence implicates high insulin secretion as a cause rather than consequence of T2D; therefore, upregulated BCF in AA may specifically confer increased risk of T2D in this cohort. Racial disparities in the metabolic characteristics of T2D have direct implications for the treatment and health consequences of this disease; therefore, future research is needed to determine whether strategies to reduce insulin secretion in AA may prevent or delay T2D and lessen racial health disparities.

Racial Differences in Weight Loss Among Adults in a Behavioral Weight Loss Intervention: Role of Diet and Physical Activity

BACKGROUND

African-Americans lose less weight during a behavioral intervention compared with Whites, which may be from differences in dietary intake or physical activity.

METHODS

Subjects (30% African American, 70% White; n = 346; 42.4 ± 9.0 yrs.; BMI = 33.0 ± 3.7 kg/m2) in an 18-month weight loss intervention were randomized to a standard behavioral (SBWI) or a stepped-care (STEP) intervention. Weight, dietary intake, self-report and objective physical activity, and fitness were assessed at 0, 6, 12, and 18 months.

RESULTS

Weight loss at 18 months was greater in Whites (-8.74 kg with 95% CI [-10.10, -7.35]) compared with African Americans (-5.62 kg with 95% CI [-7.86, -3.37]) (P = .03) in the SBWI group and the STEP group (White: -7.48 kg with 95% CI [-8.80, -6.17] vs. African American: -4.41kg with 95% CI [-6.41, -2.42]) (P = .01). Patterns of change in dietary intake were not different between groups. Objective physical activity (PA) changed over time (P < .0001) and was higher in Whites when compared with African Americans (P = .01).

CONCLUSIONS

Whites lost more weight (3.10 kg) than African American adults. Although there were no differences in dietary intake, Whites had higher levels of objective PA and fitness. Thus, the discrepancy in weight loss may be due to differences in PA rather than dietary intake. However, the precise role of these factors warrants further investigation.

Gender differences in diet and nutrition among adults initiating antiretroviral therapy in Dar es Salaam, Tanzania

Human immunodeficiency virus (HIV)-infected males have poor treatment outcomes after initiation of antiretroviral therapy (ART) compared to HIV-infected women. Dietary factors might mediate the association between sex and disease progression. However, the gender difference in diet among HIV-infected individuals in sub-Saharan Africa is largely unknown. The objective of this study was to examine differences in dietary intake among HIV-infected men and women. We conducted a cross-sectional analysis of dietary questionnaire data from 2038 adults initiating ART in Dar es Salaam, Tanzania to assess whether nutrient adequacy differed by sex. We dichotomized participants' nutrient intakes by whether recommended dietary allowances (RDAs) were met and estimated the relative risk (RR) of meeting RDAs in males using binomial regression models. We also estimated the mean difference in intake of foods and food groups by gender. We found poorer dietary practices among men compared to women. Males were less likely to meet the RDAs for micronutrients critical for slowing disease progression among HIV patients: niacin (RR = 0.39, 95% confidence interval [CI]: 0.27 to 0.55), riboflavin (RR = 0.81, 95% CI: 0.73 to 0.91), vitamin C (RR = 0.94, 95% CI: 0.89 to 1.00), and zinc (RR = 0.06, 95% CI: 0.01 to 0.24). Intake of thiamine, pantothenate, vitamins B6, B12, and E did not vary by gender. Males were less likely to eat cereals (mean difference [servings per day] = -0.21, 95% CI: -0.44 to 0.001) and vegetables (mean difference = -0.47, 95% CI: -0.86 to -0.07) in their diet, but more likely to have meat (mean difference = 0.14, 95% CI: 0.06 to 0.21). We conclude that male HIV patients have poorer dietary practices than females, and this may contribute to faster progression of the disease in males.

Low cardiorespiratory fitness in African Americans: a health disparity risk factor?

Low cardiorespiratory fitness (CRF) is a well-established risk factor for all-cause and cardiovascular disease mortality. African Americans have higher rates of cardiovascular disease compared with their Caucasian counterparts. However, the extent to which lower CRF levels contribute to the excess risk in African Americans has not been fully explored. The purpose of this review is to: (i) explore the literature evaluating the relationship between CRF and mortality specifically in African American populations; and (ii) critically evaluate the studies which have compared CRF between African American and Caucasians in epidemiological studies and clinical trials. We have further discussed several potential mechanisms that may contribute to the observation of lower CRF levels in African American compared with Caucasian adults, including potential racial differences in physical activity levels, muscle fiber type distribution, and hemoglobin levels. If lower CRF is generally present in African Americans compared with Caucasians, and is of a clinically meaningful difference, this may represent an important public health concern.

Examining Dose of Diabetes Group Medical Visits and Characteristics of the Uninsured

Type 2 diabetes is a significant problem for the uninsured. Diabetes Group Medical Visits (DGMVs) have been reported to improve outcomes. However, it is not known if the increased workload of the health care team to treat and educate patients at multiple visits has an impact on patient functioning and well-being. The aim of this study was to explore the impact of dose of DGMVs on biophysical outcomes of care in uninsured persons with diabetes. No significant correlations were found between number of DGMVs attended and biophysical outcomes of care. However, the majority of patients attended two or less DGMVs in 1 year. Dose of DGMVs did not impact outcomes and may not be enough to assure attendance. Involving patients to construct patient-centered interventions may decrease the treatment burden faced by both patients and providers. In addition, such interventions should be aimed at understanding reasons for low attendance, particularly in rural impoverished adults.

Longitudinal change in energy expenditure and effects on energy requirements of the elderly

Background

Very little is known about the longitudinal changes in energy requirements in late life. The purposes of this study were to: (1) determine the energy requirements in late life and how they changed during a 7 year time-span, (2) determine whether changes in fat free mass (FFM) were related to changes in resting metabolic rate (RMR), and (3) determine the accuracy of predicted total energy expenditure (TEE) to measured TEE.

Methods

TEE was assessed via doubly labeled water (DLW) technique in older adults in both 1999 (n = 302; age: 74 ± 2.9 yrs) and again in 2006 (n = 87 age: 82 ± 3.1 yrs). RMR was measured with indirect calorimetry, and body composition was assessed with dual-energy x-ray absorptiometry.

Results

The energy requirements in the 9th decade of life were 2208 ± 376 kcal/d for men and 1814 ± 337 kcal/d for women. This was a significant decrease from the energy requirements in the 8th decade of life in men (2482 ± 476 kcal/d vs. 2208 ± 376 kcal/d) but not in women (1892 ± 271 kcal/d vs. 1814 ± 337 kcal/d). In addition to TEE, RMR, and activity EE (AEE) also decreased in men, but not women, while FFM decreased in both men and women. The changes in FFM were correlated with changes in RMR for men (r = 0.49, p < 0.05) but not for women (r = −0.08, ns). Measured TEE was similar to Dietary Reference Intake (DRI) predicted TEE for men (2208 ± 56 vs. 2305 ± 35 kcal/d) and women (1814 ± 42 vs. 1781 ± 20 kcal/d). However, measured TEE was different than the World Health Organization (WHO) predicted TEE in men (2208 ± 56 vs. 2915 ± 31 kcal/d (p < 0.05)) and women (1814 ± 42 vs. 2315 ± 21 kcal/d (p < 0.05)).

Conclusions

TEE, RMR and AEE decreased in men, but not women, from the 8th to 9th decade of life. The DRI equation to predict TEE was comparable to measured TEE, while the WHO equation over-predicted TEE in our elderly population.

High energy expenditure masks low physical activity in obesity

OBJECTIVE

To investigate energy expenditure in lean and obese individuals, focusing particularly on physical activity and severely obese individuals.

DESIGN

Total daily energy expenditure (TDEE) was assessed using doubly labeled water, resting metabolic rate (RMR) by indirect calorimetry, activity energy expenditure (AEE) by difference and time spent in physical activity by multisensor activity monitors.

SUBJECTS

In all, 177 lean, Class I and severely obese individuals (age 31-56 years, body mass index 20-64 kg m(-2)) were analyzed.

RESULTS

All components of energy expenditure were elevated in obese individuals. For example, TDEE was 2404±95 kcal per day in lean and 3244±48 kcal per day in Class III obese individuals. After appropriate adjustment, RMR was similar in all groups. Analysis of AEE by body weight and obesity class indicated a lower AEE in obese individuals. Confirming lower physical activity, obese individuals spent less time engaged in moderate-to-vigorous physical activity (2.7±1.3, 1.8±0.6, 2.0±1.4 and 1.2±1.0 h per day in lean, Class I, Class II and Class III individuals) and more time in sedentary behaviors.

CONCLUSIONS

There was no indication of metabolic efficiency in even the severely obese, as adjusted RMR was similar across all groups. The higher AEE observed in the obese is consistent with a higher cost of activities due to higher body weight. However, the magnitude of the higher AEE (20-25% higher in obese individuals) is lower than expected (weight approximately 100% higher in Class III individuals). Confirming a lower volume of physical activity in the obese, the total time spent in moderate-to-vigorous physical activity and average daily metabolic equivalent of task level were lower with increasing obesity. These findings demonstrate that high body weight in obese individuals leads to a high TDEE and AEE, which masks the fact that they are less physically active, which can be influenced by duration or intensity of activity, than in lean individuals.

Do African American women require fewer calories to maintain weight?: Results from a controlled feeding trial

BACKGROUND

The high prevalence of obesity in African American (AA) women may result, in part, from a lower resting metabolic rate (RMR) than non-AA women. If true, AA women should require fewer calories than non-AA women to maintain weight. Our objective was to determine in the setting of a controlled feeding study, if AA women required fewer calories than non-AA women to maintain weight.

MATERIALS AND METHODS

This analysis includes 206 women (73% AA), aged 22-75 years, who participated in the Dietary Approaches to Stop Hypertension (DASH) trial-a multicenter, randomized, controlled, feeding study comparing the effects of 3 dietary patterns on blood pressure in individuals with prehypertension or stage 1 hypertension. After a 3-week run-in, participants were randomized to 1 of 3 dietary patterns for 8 weeks. Calorie intake was adjusted during feeding to maintain stable weight. The primary outcome of this analysis was average daily calorie (kcal) intake during feeding.

RESULTS

AA women had higher baseline weight and body mass index than non-AA women (78.4 vs 72.4 kg, P < .01; 29.0 vs 27.6 kg/m(2), P < .05, respectively). During intervention feeding, mean (SD) kcal was 2168 (293) in AA women and 2073 (284) in non-AA women. Mean intake was 94.7 kcal higher in AA women than in non-AA women (P < .05). After adjustment for potential confounders, there was no difference in caloric intake between AA and non-AA women (Δ = -2.8 kcal, P = .95).

CONCLUSION

These results do not support the view that AA women are at greater risk for obesity because they require fewer calories to maintain weight.

Explaining the female black-white obesity gap: a decomposition analysis of proximal causes

There exist remarkably large differences in body weights and obesity prevalence between black and white women in the United States; and crucially, these differences are a significant contributor to black-white inequalities in health. In this article, we investigate the most proximal explanations for the weight gap: namely, differences in diet and exercise. More specifically, we decompose black-white differences in body mass index and waist-to-height ratio into components reflecting black-white differences in energy intake and energy expenditure. The analysis indicates that overconsumption is much more important than a lack of exercise in explaining the weight gap, which suggests that diet interventions will have to play a fundamental role if the weight gap between black and white women is to decline.

The contribution of race and diabetes status to metabolic flexibility in humans

Factors controlling metabolic flexibility (MF), the ability of the body to switch from fat to carbohydrate oxidation in response to feeding or with insulin administration, are being actively investigated. We sought to determine the effects of race (African American vs Caucasian) and diabetes status (nondiabetic vs type 2 diabetes mellitus individuals) on MF to glucose in humans. Respiratory quotient (RQ) and macronutrient substrate utilization were evaluated by indirect calorimetry during baseline (fasting) and hyperinsulinemic-euglycemic clamp (insulin infusion of 120 mU x m(-2) x min(-1)); DeltaRQ (MF) = clamp RQ - fasting RQ. The study included 168 human subjects of different races (55 African Americans, 113 Caucasians), sex (73 men, 95 women), ages (18-73 years), body mass index (19.3-47.7 kg/m(2)), and diabetes status (89 nondiabetic, 79 type 2 diabetes mellitus subjects). Metabolic flexibility was negatively correlated (P < .01) with age (r = - 0.41), fasting RQ (r = -0.22), fasting glucose (r = -0.55), insulin (r = -0.40), and triglyceride (r = -0.44) concentrations; whereas a positive association was observed with insulin sensitivity (r = 0.69, P < .0001). Insulin sensitivity, fasting RQ, triglyceride concentrations, diabetes status, and race accounted for 71% of the variability in MF with insulin sensitivity being the main determinant factor (model R(2) = 0.48, P < .0001). After controlling for the significant predictors, MF was higher in African Americans vs Caucasians (mean +/- SEM 0.080 +/- 0.004 vs 0.069 +/- 0.002, P = .008) and in nondiabetic vs type 2 diabetes mellitus subjects (P = .003). This study confirms that insulin sensitivity is the major contributor to MF in humans, but provides the novel findings that African Americans have significantly greater MF than Caucasians even after adjusting for insulin sensitivity and diabetes status.

Resting energy expenditure changes with weight loss: racial differences

It is controversial whether weight loss reduces resting energy expenditure (REE) to a different magnitude in black and white women. This aim of this study was to determine whether changes in REE with weight loss were different between black and white postmenopausal women, and whether changes in body composition (including regional lean and fat mass) were associated with REE changes within each race. Black (n = 26) and white (n = 65) women (age = 58.2 +/- 5.4 years, 25 < BMI < 40 kg/m(2)) completed a 20-week weight-loss intervention. Body weight, lean and fat mass (total body, limb, and trunk) via dual-energy X-ray absorptiometry, and REE via indirect calorimetry were measured before and after the intervention. We found that baseline REE positively correlated with body weight, lean and fat mass (total, limb, and trunk) in white women only (P < 0.05 for all). The intervention decreased absolute REE in both races similarly (1,279 +/- 162 to 1,204 +/- 169 kcal/day in blacks; 1,315 +/- 200 to 1,209 +/- 185 kcal/day in whites). REE remained decreased after adjusting for changes in total or limb lean mass in black (1,302-1,182 kcal/day, P = 0.043; 1,298-1,144 kcal/day, P = 0.006, respectively), but not in white, women. Changes in REE correlated with changes in body weight (partial r = 0.277) and fat mass (partial r = 0.295, 0.275, and 0.254 for total, limb, and trunk, respectively; P < 0.05) independent of baseline REE in white women. Therefore, with weight loss, REE decreased in proportion to the amount of fat and lean mass lost in white, but not black, women.

Resting energy expenditure: a stronger marker than body weight for bone mineral density in white women but not men? The Rancho Bernardo study

OBJECTIVE

To investigate the association between resting energy expenditure (REE) and bone mineral density (BMD) in white adults.

DESIGN

Cross-sectional study.

SETTING

White, middle-class to upper middle-class community-dwelling adults.

PARTICIPANTS

Women (n = 996) and men (n = 686) aged 36 to 97 years.

ASSESSMENT OF RISK FACTORS

REE calculated using the Harris-Benedict equation.

MAIN OUTCOME MEASURES

BMD of the lumbar spine (L1 to L4), total hip, and total body measured using dual energy x-ray absorptiometry.

RESULTS

REE was lower in women than in men (1220 versus 1566 kcal/day, P < 0.0001); women also had lower BMI. After adjusting for lean body mass (LBM), REE was higher in women than men (1407 versus 1296 kcal/kg LBM/d, P < 0.0001). In stepwise multiple linear regression models, REE explained 13% of variance in spine BMD in women and 6% in men, 33% of variance in hip BMD in women and 22% in men, and 32% of variance in total body BMD in women and 22% in men. In women, weight explained 10% less of the hip BMD variance and 6% less of the total body BMD variance than REE. In men, weight explained 4% more of the spine BMD variance and 1% more of the total body BMD variance than REE.

CONCLUSIONS

REE explained more of the BMD variance than weight in women, and the reverse was true in men. These sex differences were largely explained by sex differences in LBM or weight.

DIFFERENCES IN EXERCISE PERFORMANCE AND LEISURE-TIME PHYSICAL ACTIVITY IN OLDER CAUCASIANS AND AFRICAN-AMERICANS

PURPOSES: (a) To compare exercise performance and leisure-time physical activity (LTPA) between older Caucasians and African-Americans, (b) to assess the relationship between exercise performance and LTPA, and (c) to determine whether group differences in exercise performance persist after adjusting for differences in LTPA. METHODS: A total of 207 Caucasians and 160 African-Americans who were 65 years of age and older participated in this study. Subjects were characterized on exercise performance by a 6-minute walk test, and by a short physical performance battery (SPPB) score consisting of a repeated chair rise test, a standing balance test, and a 4-meter walk test. Additionally, LTPA was assessed using the Minnesota LTPA questionnaire. RESULTS: African-Americans had a 16% lower SPPB value (P < 0.001), a 14% shorter 6-minute walk distance (P < 0.001), and a 34% lower LTPA value (P < 0.011) than the Caucasians. LTPA was significantly related (P < 0.01) to both SPPB and 6-minute walk distance in both groups. Differences in SPPB and 6-minute walk distance between older Caucasians and African-Americans were no longer present (P > 0.05) after controlling for LTPA. CONCLUSIONS: Older African-Americans had impaired exercise performance and lower LTPA compared to older Caucasians. Racial differences in exercise performance were no longer present after adjusting for differences in LTPA.

Do sex or race differences influence strength training effects on muscle or fat?

PURPOSE

To examine the influence of sex and race on the effects of strength training (ST) on thigh muscle volume (MV), midthigh subcutaneous fat (SCF), and intermuscular fat (IMF).

METHODS

One hundred eighty-one previously inactive healthy Caucasian (N = 117) and African American (N = 54) men (N = 82) and women (N = 99), aged 50-85 yr, underwent about 10 wk of unilateral knee extension ST. Ten subjects were neither Caucasian nor African American and were, therefore, not included in the race analysis. Quadriceps MV and midthigh SCF and IMF cross-sectional area were measured with computed tomography before and after ST. Sex and race comparisons were made with a 2 x 2 (sex by race) analysis of covariance.

RESULTS

Training-induced increases in absolute MV were significantly greater (P < 0.001) in men than in women, though both sex groups increased MV significantly with ST (P < 0.001), and the relative (%) increases were similar. There were significant increases in MV within race groups (P < 0.001), but no significant differences between races. There were no significant changes in SCF or IMF, whether sex and racial groups were separated or combined. In addition, there was no sex by race interaction for changes in MV, SCF, or IMF with ST.

CONCLUSION

Strength training does not alter subcutaneous or intermuscular fat, regardless of sex or racial differences. Although men exhibit a greater muscle hypertrophic response to strength training than do women, the difference is small. Race does not influence this response.

Estimation of resting energy expenditure considering effects of race and diabetes status

OBJECTIVE

To evaluate the impact of diabetes status and race, in addition to other covariables, on the estimation of resting energy expenditure (REE).

RESEARCH DESIGN AND METHODS

Demographic, anthropometric, and clinical parameters were assessed in 166 adults of varying weights. Subjects were categorized by race (white versus black) and into three subgroups based on glucose tolerance (normoglycemia, impaired glucose tolerance, and type 2 diabetes), termed the diabetes status index (DSI). REE was measured by indirect calorimetry. A multiple regression model was established for optimal prediction of REE based on covariables.

RESULTS

An average decrease in REE of 135 kcal/day independent of all other variables was observed in blacks (P < 0.001). DSI was found to be a significant covariable (P = 0.002) in predicting REE, which was observed to be higher in diabetic women. Therefore, race and DSI entered the multiple regression equation to predict REE as significant independent variables, together with lean body mass (LBM) and age x BMI interaction (P < 0.001). Overall, REE prediction resulted in an R(2) of 0.79 and a root mean square error of 136 kcal/day. These values indicate that the resultant equations could offer advantages over other key published prediction equations. The equations are: 1) REE(female) = 803.8 + 0.3505 x age x (BMI - 34.524) - 135.0 x race + 15.866 x LBM + 50.90 x DSI; and 2) REE(male) = 909.4 + 0.3505 x age x (BMI -34.524) -135.0 x race + 15.866 x LBM -9.10 x DSI. The predictive value of the equations did not diminish substantially when fat-free mass estimated by skinfold calipers was substituted for dual-energy X-ray absorptiometry scan measurements of LBM.

CONCLUSIONS

Race and diabetes status are important when predicting REE, coupled with LBM, age, BMI, and sex. Race and DSI have not been considered in equations commonly used to predict REE. Their inclusion could improve individualization of dietary prescriptions for type 2 diabetic subjects and heterogeneous populations.

Cigarette smoking is associated with energy balance in premenopausal African-American adult women differently than in similarly aged white women

OBJECTIVE

To investigate the differential association of cigarette smoking with energy balance in African-American and white premenopausal women.

DESIGN

Cross-sectional study of energy balance, weight, and smoking in women.

SUBJECT

A total of 374 women: 191 African-American (mean age=29.8+/-6.5 y) and 183 white women (mean age=28.9+/-7.1 y).

MEASUREMENTS

Weight, cigarette smoking habits, resting energy expenditure, dietary intake, and physical activity.

RESULTS

There were no significant differences in dietary intake by race or smoking status. The model for physical activity was significant (P=0.0004), with body mass index (BMI) having the largest effect on activity (P<0.001). Smoking status was related to activity, with the heaviest smokers reporting more activity than nonsmokers (P=0.008) or light smokers (P=0.028). The model for resting energy expenditure (REE) was significant (P<0.0001), with the largest again being BMI (P<0.001). There was also an interaction between ethnicity and smoking status (P<0.0001) such that African-American nonsmokers and light smokers tended to have lower REE than several other groups, most often the African-American moderate heavy smokers. The model for BMI was significant (P<0.0001) with an interaction for ethnicity and smoking status (P=0.0009). African-American nonsmokers and light smokers had significantly higher BMIs than most of the other groups.

CONCLUSION

African-American women who were the heaviest smokers had a lower adjusted BMI than the heaviest smoking white women. This effect, at least partially, may be related to an increased REE in the African-American smoking women. While energy intake did not appear to be important in this relationship, energy expended in physical activity appeared to be increased with smoking, as was REE.

Racial differences in insulin resistance and mid-thigh fat deposition in postmenopausal women

OBJECTIVE

To determine whether racial differences in insulin resistance between African American (AA) and white women exist in postmenopausal women and whether they are related to physical fitness and/or obesity.

RESEARCH METHODS AND PROCEDURES

We studied 35 obese AA (n = 9) and white (n = 26) women of comparable maximal oxygen consumption, obesity, and age. Total body fat was measured by DXA. Abdominal and mid-thigh low-density lean tissue (a marker of intramuscular fat) were determined with computed tomography. Glucose utilization (M) was measured during the last 30 minutes of a 3-hour hyperinsulinemic-euglycemic clamp. Insulin sensitivity was estimated from the relationship of M to the concentration of insulin during the last 30 minutes of the clamp.

RESULTS

The percentage of fat and total body fat mass were similar between AA and white women, whereas fat-free mass was higher in African American women. Visceral adipose tissue was not different between groups, but subcutaneous abdominal fat was 17% higher in the AA than in the white women. AA women had an 18% greater mid-thigh muscle area (p < 0.01) and a 34% greater mid-thigh low-density lean tissue area than the white women. Fasting glucose concentrations were not different, but fasting insulin concentrations were 29% higher in AA women. Glucose utilization was 60% lower in the AA women because of a lower non-oxidative glucose disposal. Insulin sensitivity was 46% lower in the AA women.

DISCUSSION

AA postmenopausal women have more mid-thigh intramuscular fat, lower glucose utilization, and are less insulin sensitive than white women despite comparable fitness and relative body fat levels.

Fatty acid oxidation in African-American and Caucasian women during physical activity

The goal of this study was to determine whether differences in physical activity-related fat oxidation exist between lean and obese African-American (LAA and OAA) and lean and obese Caucasian (LC and OC) premenopausal women. Lean AA (28.4 +/- 2.8 yr, n = 7), LC (24.7 +/- 1.8 yr, n = 9), OAA (30.9 +/- 2.2 yr, n = 11), and OC (34.1 +/- 2.5 yr, n = 9) women underwent preliminary assessment of peak aerobic capacity (VO2 peak). On a subsequent testing day, participants exercised after an 8-h fast on a cycle ergometer at 15 W (approximately 40% VO2 peak) for 10 min and then for 10 min at approximately 65% VO2 peak). Fatty acid oxidation was determined using the average respiratory exchange ratio and O2 consumption during minutes 5-9 of the exercise session. Percent body fat and fat-free mass were lower (P < 0.05) in LAA (25.8 +/- 2.8% and 48.3 kg) and LC (26.4 +/- 2.0% and 45.8 +/- 1.7 kg) than in OAA (41.2 +/- 1.3% and 58.8 +/- 3.3 kg) and OC (39.3 +/- 2.7% and 58.6 kg) women. Fat oxidation among the groups was analyzed statistically using analysis of covariance with fat-free mass and VO2 peak) as covariates. During exercise at 15 W, fat oxidation was as low in LAA (0.134 +/- 0.024 g/min) as in OAA (0.144 +/- 0.026 g/min) and OC (0.156 +/- 0.020 g/min) women: all these rates of fat oxidation were lower than in LC women (0.200 +/- 0.021 g/min, P < 0.05, LC vs. all other groups). Fatty acid oxidation during higher-intensity exercise (65% VO2 peak)) was higher in LC than in OC women but was not statistically different between African-American and Caucasian groups. Fatty acid oxidation was therefore lower during low-intensity physical activity in OAA, LAA, and OC than in LC women.