DXA: Potential for Creating a Metabolic Map of Organ-Tissue Resting Energy Expenditure Components

Objective: This study tested the hypothesis that tissue-organ components can be derived from DXA measurements, and in turn, resting energy expenditure (REE) can be calculated from the summed heat productions of DXA-estimated brain, skeletal muscle mass (SM), adipose tissue, bone, and residual mass (RM). Research Methods and Procedures: Subjects were divided into five groups of adults <50 years of age. The specific metabolic rate of RM was developed in 13 Group I healthy subjects and a DXA-brain mass prediction formula in 52 Group II subjects. SM, adipose tissue, and bone models were developed based on earlier reports. The composite REE prediction model (REEp) was tested in 154 Group III subjects in whom REEp was compared with measured REE (REEm). Features of the developed model were determined in 94 normal-weight men and women (Group IV) and seven spinal cord injury patients and healthy matched controls (Group V). Results: REEp and REEm in Group III were highly correlated (y = 0.85x + 233; r = 0.82, p < 0.001), and no bias was detected. Both REEm (mean ± SD, 1579 ± 324 kcal/d) and REEp (1585 ± 316 kcal/d) were also highly correlated (r values = 0.85 to 0.98; p values < 0.001) and provided similar group values to REE estimated by the Harris-Benedict equations (1597 ± 279 kcal/d) and Wang's composite fat-free mass–based REE equation (1547 ± 248 kcal/d). New insights into the sources and distribution of REE were provided by analysis of the demonstration groups. Discussion: This approach offers a new practical and educational opportunity to examine REE in subject groups using modeling strategies that reveal the magnitude and distribution of fundamental somatic heat-producing units.     

Bioimpedance for severe obesity: comparing research methods for total body water and resting energy expenditure

Objective: As the acceptance of surgical procedures for weight loss in morbid obesity is increasing, clinically useful baseline and follow‐up measures of total body water (TBW) and resting energy expenditure (REE) are important. Research methods such as deuterium (D²O) dilution and metabolic carts are problematic in the clinical setting. We compared bioimpedance analysis (BIA) predicted (Tanita TBF‐310) and measured TBW and REE. Methods and Procedures: Forty‐two paired presurgery studies were completed using BIA and D²O in patients with BMI (mean ± s.d.) 50.2 ± 8.8 kg/m² for TBW, and 30 patients with BMI 51.0 ± 13 kg/m² completed paired determinations of REE with metabolic carts and the Tanita balance with weight, height, sex, and age modifiers. Regression analysis and Bland‐Altman plots were applied. Results: When regression analysis was completed for TBW, regression line was consistent with the identity line “y = x.” The intercept was not different from 0 (95% confidence interval ?2.5 ± 7.0). The slope of the line was not different from 1.0 ± 0.1. The measured TBW 51.2 ± 10.1 l had a correlation with the predicted 49.5 ± 11.27 l of 0.92. There also was no significant difference (P = 0.33) between predicted (2,316 ± 559 kcal/day) and measured REE (2,383 ± 576 kcal/day);δ 66.7 ± 273 kcal/day. The two measures were highly correlated (r = 0.88) with no bias detected. Discussion: These observations support the use of the BIA system calibration in subjects with severe obesity. Without the use of complex, costly equipment and invasive procedures, BIA measurements can easily be obtained in clinical practice to monitor patient responses to treatment.     

Increased resting energy expenditure after 40 minutes of aerobic but not resistance exercise

Objective: Resting energy expenditure (REE) is increased 24 hours after high‐intensity aerobic exercise lasting 60 minutes, whereas results have been inconsistent after resistance training and aerobic exercise of shorter duration. The objective of the study was to compare the effects of 40 minutes of high‐intensity aerobic vs. resistance exercise on REE 19 to 67 hours after exercise. Research Methods and Procedures: REE was compared 19, 43, and 67 hours after 40 minutes of aerobic training (AT; 80% maximum heart rate) or resistance training (RT; 10 repetitions at 80% maximum strength, two sets and eight exercises). Twenty‐three black and 22 white women were randomly assigned to AT, RT, or no training (controls). Exercisers trained 25 weeks. REE was measured after a 12‐hour fast. Results: There was a significant time × group interaction for REE when adjusted for fat‐free mass and fat mass, with post hoc tests revealing that the 50‐kcal difference between 19 and 43 hours (1310 ± 196 to 1260 ± 161 kcal) and the 34‐kcal difference between 19 and 67 hours (1310 ± 196 to 1276 ± 168 kcal) were significant for AT. No other differences were found, including RT (19 hours, 1256 ± 160; 43 hours, 1251 ± 160; 67 hours, 1268 ± 188 kcal). Urine norepinephrine increased with training only in AT. After adjusting for fat‐free mass, REE Δ between 19 and both 43 and 67 hours was significantly related to urine norepinephrine (r = 0.76, p < 0.01 and 0.68, p < 0.03, respectively). Discussion: Consistent with findings on longer duration AT, these results show that 40 minutes of AT elevates REE for 19 hours in trained black and white women. This elevation did not occur with 40 minutes of RT. Results suggest that differences are, in part, due to increased sympathetic tone.     

Influence of Sibutramine on Energy Expenditure in African American Women

Objective: African American women have a high prevalence of obesity, which partially may be explained by their lower rates of resting energy expenditure (REE). The aim of this study was to examine the influence of acute sibutramine administration on REE and post‐exercise energy expenditure in African American women. Research Methods and Procedures: A total of 15 premenopausal, African American women (age, 29 ± 5 years; body fat, 38 ± 7%) completed a randomized, double‐blind cross‐over design with a 30‐mg ingestion of sibutramine or a placebo. Each trial was completed a month apart in the follicular phase and included a 30‐minute measurement of REE 2.5 hours after sibutramine or placebo administration. This was followed by 40 minutes of cycling at ～70% of peak aerobic capacity and a subsequent 2‐hour measurement of post‐cycling energy expenditure. Results: There was no difference (p > 0.05) in REE (23.70 ± 2.81 vs. 23.69 ± 2.95 kcal/30 min), exercise oxygen consumption (1.22 ± 0.15 vs. 1.25 ± 0.15 liter/min), and post‐cycling energy expenditure (104.2 ± 12.7 vs. 104.9 ± 11.4 kcal/120 min) between the sibutramine and placebo trials, respectively. Cycling heart rate was significantly higher (p = 0.01) during the sibutramine (158 ± 14 beats/min) vs. placebo (150 ± 12 beats/min) trials. Discussion: These data demonstrate that acute sibutramine ingestion does not increase REE or post‐exercise energy expenditures but does increase exercising heart rate in overweight African American women. Sibutramine may, therefore, impact weight loss through energy intake and not energy expenditure mechanisms.     

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/m²) 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.     

不同体位对严重肥胖者血氧饱和度的影响

目的:探讨不同体位对严重肥胖者血氧饱和度的影响。方法:16名平均体重指数(BMI)为40±5肥胖者和16名年龄匹配的正常体重者被纳入研究。分别在不同体外下(坐位、仰卧位、侧卧位)对所有参与者进行动脉血气监测。结果:肥胖者于坐位时动脉Pa O_2为75±4 mm Hg,Pa CO_2为37±3 mm Hg;仰卧位时动脉Pa O_2为62±5 mm Hg,Pa CO_2为47±5 mm Hg;侧卧位时Pa O_2为73±3 mm Hg,Pa CO_2为39±2 mm Hg;而正常体重者无明显变化。结论:严重肥胖者于平卧位时更容易出现低氧及高碳酸血症。     

Obesity Prevention in Preschool Native‐American Children: A Pilot Study Using Home Visiting

Objective : To determine whether maternal participation in an obesity prevention plus parenting support (OPPS) intervention would reduce the prevalence of obesity in high‐risk Native‐American children when compared with a parenting support (PS)‐only intervention. Research Methods and Procedures : Forty‐three mother/child pairs were recruited to participate. Mothers were 26.5 ± 5 years old with a mean BMI of 29.9 ± 3 kg/m². Children (23 males) were 22 ± 8 months old with mean weight‐for‐height z (WHZ) scores of 0.73 ± 1.4. Mothers were randomly assigned to a 16‐week OPPS intervention or PS alone. The intervention was delivered one‐on‐one in homes by an indigenous peer educator. Baseline and week 16 assessments included weight and height (WHZ score and weight‐for‐height percentile for children), dietary intake (3‐day food records), physical activity (measured by accelerometers), parental feeding style (Child Feeding Questionnaire), and maternal outcome expectations, self‐efficacy, and intention to change diet and exercise behaviors. Results : Changes in WHZ scores showed a trend toward significance, with WHZ scores decreasing in the PS condition and increasing among the OPPS group (?0.27 ± 1.1 vs. 0.31 ± 1.1, p = 0.06). Children in the OPPS condition also significantly decreased energy intake (?316 ± 835 kcal/d vs. 197 ± 608 kcal/d, p < 0.05). Scores on the restriction subscale of the Child Feeding Questionnaire decreased significantly in the OPPS condition (?0.22± 0.42 vs. 0.08± 0.63, p < 0.05), indicating that mothers in the OPPS group were engaging in less restrictive child feeding practices over time. Discussion : A home‐visiting program focused on changing lifestyle behaviors and improving parenting skills showed promise for obesity prevention in high‐risk Native‐American children.     

Physical activity-related energy expenditure with the RT3 and TriTrac accelerometers in overweight adults

Objective: The objective was to evaluate two accelerometers, the RT3 and the TriTrac‐R3D for their ability to produce estimates of physical activity‐related energy expenditure (PAEE) in overweight/obese adults. Research Methods and Procedures: PAEE estimates from both accelerometers were obtained in two experiments. In Experiment 1, 13 overweight/obese subjects (BMI 34.2 ± 6.4 kg/m²) were monitored over 2 weeks in everyday life, PAEE being simultaneously measured by the doubly labeled water method (DLW). In Experiment 2, 8 overweight/obese subjects (BMI 34.3 ± 5.0 kg/m²) and 10 normal‐weight subjects (BMI 20.8 ± 2.1 kg/m²) were monitored during a treadmill walking protocol, PAEE being simultaneously measured by indirect calorimetry. Results: In Experiment 1, there was no significant difference between methods in mean PAEE (DLW: 704 ± 223 kcal/d, RT3: 656 ± 140 kcal/d, TriTrac‐R3D 624 ± 419 kcal/d). The relative difference between methods (accelerometer vs. DLW) was ?17.1% ± 16.7% for the RT3 and ?20.0 ± 44.6% for the TriTrac‐R3D. Correlation for PAEE between RT3 and DLW was higher than between TriTrac‐R3D and DLW (r = 0.67, p < 0.05 and r = 0.36, p = 0.25, respectively). The 95% confidence interval (CI) (kcal/d) of the mean difference between methods was large, amounting to ?385 to 145 for the RT3 and ?887 to 590 for the TriTrac‐R3D. In Experiment 2, both accelerometers were sensitive to the changes in treadmill speed, with no significant difference in mean PAEE between methods in overweight/obese subjects. Conclusions: Although both accelerometers did not provide accurate estimates of PAEE at individual levels, the data suggest that RT3 has the potential to assess PAEE at group levels in overweight/obese subjects.     

Weekly changes in basal metabolic rate with eight weeks of overfeeding

Objective : The contribution of basal metabolic rate (BMR) to weight gain susceptibility has long been debated. We wanted to examine whether BMR changes in a linear fashion with overfeeding. Our hypothesis was that BMR does not increase linearly with 1000‐kcal/d overfeeding in lean healthy subjects over 8 weeks. The null hypothesis states that BMR increases linearly with 1000‐kcal/d overfeeding in lean healthy subjects. Research Methods and Procedures : Initially, 16 lean healthy sedentary subjects completed 2 weeks of weight maintenance feeding at the General Clinical Research Center. The subjects were then overfed by 1000 kcal/d over 8 weeks. BMR was measured under standard conditions each week using indirect calorimetry. Results : Baseline BMR was 1693 ± 154.5 kcal/d. BMR increased from 1711 ± 201.3 kcal/d at week 1 of overfeeding to 1781 ± 171.65 kcal/d at the second week of overfeeding (p = 0.05). BMR fell during the third week of overfeeding to 1729 ± 179.5 kcal/d (p = 0.05). After 5 weeks of overfeeding, BMR reached a plateau. Thereafter, there was no further change. Comparison of BMR with weeks of overfeeding was significantly different compared with the linear model (p < 0.05). Discussion : Increases in BMR in lean sedentary healthy subjects with 1000‐kcal/d overfeeding are not linear over 8 weeks. There seems to be a short‐term increase in BMR in the first 2 weeks of overfeeding that is not representative of longer‐term changes.     

Energy Intake and Meal Portions: Associations with BMI Percentile in U.S. Children

Objective: We examined relationships of eating patterns and reported energy intake (rEI) with BMI percentile in U.S. children. Research Methods and Procedures: Two 24‐hour dietary recalls from the Continuing Surveys of Food Intakes by Individuals 1994 to 1996 and 1998 (1005 boys, 990 girls) were averaged, and children were categorized into three age groups: 3 to 5 years (n = 1077), 6 to 11 years (n = 537), and 12 to 19 years (n = 381). Physiologically implausible reports due to reporting bias or abnormal intake (rEI outside ±18% to 23% of predicted energy requirements; pER) were identified. Results: rEI averaged 109 ± 34% and 100 ± 10% of pER in the total and plausible samples, respectively. EI was overreported more in younger children and underreported more in overweight older children. Children with plausible rEI (45.3% of sample) averaged 4.7 eating occasions/d, 589 kcal/meal, 223 kcal/snack, and 2038 kcal/d. rEI was not associated with BMI percentile in the total sample. In the plausible sample, rEI, meal portion size, and meal energy were positively associated with BMI percentile in boys 6 to 11 years and in children 12 to 19 years. No relationships were found in children 3 to 5 years and girls 6 to 11 years. Relationships were more consistent and stronger in the plausible compared with the total sample. Discussion: Excluding implausible dietary reports may be necessary for discerning dietary associations with BMI percentile. EI and meal, but not snack, patterns may play a quantitatively greater role in weight regulation as children age.     

Sitting and Supine Esophageal Pressures in Overweight and Obese Subjects

Esophageal pressure (P_Es) can be used to approximate pleural pressure (P_pl) and might be clinically useful, particularly in the obese e.g., to guide mechanical ventilator settings in critical illness. However, mediastinal artifact (the difference between true P_pl and P_Es) may limit acceptance of the measurement, and reproducibility of P_Es measurements remains unknown. Therefore, we aimed to assess the effect of body posture on P_Es in a cohort of obese, but healthy subjects, some of whom had multiple measurements, to address the clinical robustness of esophageal manometry. Twenty‐five overweight and obese subjects (BMI > 25 kg/m²) and 11 control lean subjects (BMI < 25 kg/m²) underwent esophageal manometry with pressures measured seated and supine. Twenty overweight and obese subjects had measurements repeated after ～1 to 2 weeks. Anthropometric data and sitting and supine spirometry were recorded. The average end‐expiratory P_Es sitting and supine were greater in the overweight and obese group than the lean group (sitting ?0.1 ± 2.1 vs. ?3.3 ± 1.2 cmH₂O, supine 9.3 ± 3.3 vs. 6.9 ± 2.8 cmH₂O, respectively). The mean differences between repeated measurements were small (?0.3 ± 1.7 cmH₂O sitting and ?0.1 ± 1.5 cmH₂O supine). P_Es correlated with a number of anthropometric and spirometric variables. In conclusion, P_Es are slightly greater in overweight and obese subjects than lean subjects; but changes with position are similar in both groups. These data indicate that mediastinal weight and postural effects on P_Es are within a clinically acceptable range, and suggest that esophageal manometry can be used to inform clinical decision making across wide range of body types.     

Arg64β3‐Adrenoceptor Variant and the Components of Energy Expenditure

Objective: To determine Trp64Arg β₃‐adrenoceptor genotype‐specific differences in the components of energy expenditure. Hypothesis: We hypothesized that resting metabolic rate (RMR) and physical activity levels would be lower and that thermic effect of feeding (TEF) would be higher in those with the Arg64 allele. Research Methods and Procedures: RMR and TEF were measured by indirect calorimetry, physical activity by questionnaire, and total energy expenditure by the doubly labeled water method. Genotype‐specific measures were compared using ANOVA and analysis of covariance (ANCOVA). Results: RMR in Arg64 homozygotes was significantly lower than in Trp64 homozygotes [Arg64, 1373 ± 259 kcal/d (n = 15) vs. Trp64Arg, 1538 ± 238 kcal/d (n = 25) vs. Trp64, 1607 ± 290 kcal/d (n = 22); p < 0.01]. TEF was significantly higher in Arg64 homozygotes compared with Trp64 homozygotes (Arg64, 359 ± 28 kcal/d; Trp64Arg, 322 ± 22 kcal/d; and Trp64, 279 ± 23 kcal/d; p < 0.05). No differences were identified between genotypes in physical activity or in total energy expenditure. Discussion: Our results suggest that the Arg64 β₃‐adrenoceptor allele contributes significantly to the genetic variability in both RMR and TEF.     

Evaluation of a multisensor armband in estimating energy expenditure in obese individuals

Objective: To examine the reliability and validity of the SenseWear Pro 2 Armband (SWA; Body Media, Pittsburgh, PA) during rest and exercise compared with indirect calorimetry (IC) in obese individuals. Research Methods and Procedures: Energy expenditure was assessed during rest with the SWA and IC in 142 obese adults (37 men and 105 women, BMI = 42.3 ± 7.0) and in 25 lean and overweight adults (BMI = 25.3 ± 3.2) who were used as a comparison group. Twenty‐nine of the obese adults also participated in three separate short exercise sessions including cycle ergometry, stair stepping, and treadmill walking. Results: The repeatability of SWA estimates in obese subjects was high (r = 0.88, p < 0.001). The SWA generally underestimated the resting energy expenditure (REE) (1811 ± 346 vs. 1880 ± 382 kcal/d) and highly overestimated the energy expenditure during the exercise sessions in obese individuals. REE estimations by SWA were significantly correlated with fat‐free mass (r = 0.88, p < 0.001). Bland‐Altman plots based statistical analysis for the estimated REE, and measured IC showed a low agreement (Total Error > 20% but Systematic Error < 5%) between the two methods in obese subjects, although they showed a high correlation and a very good agreement in lean and overweight patients. Discussion: The SWA is an easy to handle, practical, new portable device for measuring energy expenditure. The accuracy of the SWA appeared to be poor in the obese subjects we examined, especially those with high REE both in rest and exercise. We believe that it is necessary to incorporate new, obesity‐specific algorithms in the relative software.     

Comparison of Methods for Achieving 24‐Hour Energy Balance in a Whole‐Room Indirect Calorimeter

Objective: To evaluate and compare methods for achieving 24‐hour energy balance in a whole‐room indirect calorimeter. Research Methods and Procedures: Twenty‐four‐hour energy expenditure (EE) for 34 healthy adults (16 women, 18 men) was measured in a calorimeter during a prestudy day and on a subsequent nonconsecutive assessment day (AD). Several methods for estimating EE on the AD using activity factors or regression equations with data available before the AD [anthropometrics, body composition, resting metabolic rate (RMR), sleeping metabolic rate (SMR) on prestudy day, 24‐hour EE on prestudy day] were compared for predictive accuracy. Results: Use of a 24‐hour calorimeter stay gave the smallest mean absolute error (119 ± 16 kcal/d) and smallest single maximum error (361 kcal/d). However, several other methods were only slightly, and not significantly, less accurate (e.g., mean absolute error = 131 ± 17, 140 ± 20, and 141 ± 22 kcal/d and greatest error = 384, 370, and 593 kcal/d for anthropometric, RMR, and SMR regression equations, respectively). Fat‐free mass alone and SMR with a simple activity factor were seen to be less accurate. Discussion: Our results indicate that there may be some improvement in achieving 24‐hour energy balance in a metabolic chamber by using a preceding 24‐hour calorimeter stay; that only slightly less accurate predictions can be obtained using a combination of anthropometric, body composition, and/or RMR measurements; and that there is little or no advantage in using SMR from a previous overnight calorimeter stay.     

Accuracy of SenseWear Pro2 Armband to Predict Resting Energy Expenditure in Childhood Obesity

Objective: The accuracy of the SenseWear Pro2 Armband (SWA) in estimating resting energy expenditure (REE) in children and adolescents with obesity, using indirect calorimetry (IC) as a reference was evaluated. Design and Methods: REE was assessed using both the SWA and IC in 40 obese subjects (26 M/14 F, age 11.5 ± 2.57 years, z‐score BMI 3.14 ± 0.53). The agreement between methods was assessed by the Bland‐Altman procedure. The relationship between REE assessments and patients' characteristics was also analyzed. Results : SWA‐ and IC‐derived estimates of REE showed a significant correlation (r = 0.614; P < 0.001), but the SWA overestimated mean REE by 13% (P < 0.001). Age and kilogram of fat‐free mass (kg‐FFM) were significantly correlated with both REE estimation by SWA (r = 0.434 and r = 0.564, respectively) and IC (r = 0.401 and r = 0.518, respectively). Only kg‐FFM was demonstrated to be the main predictor factor of REE variability (r² 79% SWA; 75% IC). Conclusions: The SWA overestimated mean REE in childhood obesity, suggesting that the SWA and IC are not yet interchangeable methods. This would require improving the SWA by developing better algorithms for predicting REE and, probably, bias in each individual REE could be reduced by an adjustment for subjects' kg‐FFM.     

Sedentariness at Work: How Much Do We Really Sit?

Sedentariness is associated with obesity. We examined whether people with sedentary jobs are equally inactive during their work days and leisure days. We enrolled 21 subjects of varying weight and body fat (11 men:10 women, 38 ± 8 years, 83 ± 17 kg, BMI 28 ± 5 kg/m², 29 ± 11 fat kg, 35 ± 9% fat). All subjects continued their usual work and leisure‐time activities whilst we measured daily activity and body postures for 10 days. The data supported our hypothesis that people sit more at work compared to leisure (597 ± 122 min/day cf 484 ± 83 min/day; P < 0.0001). The mean difference was 110 ± 99 min/day. Similarly, work days were associated with less standing (341 ± 97 min/day; P = 0.002) than leisure days (417 ± 101 min/day). Although the walking bouts did not differ significantly between work and leisure (46 ± 9 vs. 42 ± 9 walking bouts/day); the mean free‐living velocity of a walk at work was 1.08 ± 0.28 mph and on leisure days was 0.94 ± 0.24 mph (P = 0.03) and the average time spent walking was 322 ± 91 min on work days and 380 ± 108 min on leisure days (P = 0.03). Estimates of the daily energetic cost of walking approximated 527 ± 220 kcal/day for work days and 586 ± 326 kcal/day for leisure days (r = 0.72, P < 0.001). Work days are associated with more sitting and less walking/standing time than leisure days. We suggest a need to develop approaches to free people from their chairs and render them more active.     

Labor Saved,Calories Lost: The Energetic Impact of Domestic Labor‐saving Devices

Objective: As the prevalence of obesity has increased, so has sedentariness. Progressive sedentariness has been attributed to greater use of labor saving devices, such as washing machines, and less nonexercise walking (e.g., walking to work). However, there is a paucity of data to support this conclusion. In this study, we address the hypothesis that domestic mechanization of daily tasks has resulted in less energy expenditure compared with performing the same tasks manually. Research Methods and Procedures: Energy expenditure was measured in four groups of subjects (122 healthy adult men and women total) from Rochester, Minnesota. Energy expenditure was measured using indirect calorimetry while subjects performed structured tasks such as cleaning dishes and clothes, stair climbing, and work‐associated transportation, and these values were compared with the respective mechanized activity. Results: Energy expenditure was significantly greater and numerically substantial when daily domestic tasks were performed without the aid of machines or equipment (clothes washing: 45 ± 14 vs. 27 ± 9 kcal/d; dish washing: 80 ± 28 vs. 54 ± 19 kcal/d; transportation to work: 83 ± 17 vs. 25 ± 3 kcal/d; stair climbing: 11 ± 7 vs. 3 ± 1 kcal/d; p < 0.05). The combined impact of domestic mechanization was substantial and equaled 111 kcal/d. Discussion: The magnitude of the energetic impact of the mechanized tasks we studied was sufficiently great to contribute to the positive energy balance associated with weight gain. Efforts focused on reversing sedentariness have the potential to impact obesity.     

Modest Lifestyle Intervention and Glucose Tolerance in Obese African Americans

Objective: Previous studies have demonstrated the benefit of short‐term diets on glucose tolerance in obese individuals. The purpose of this study was to evaluate the effectiveness of modest lifestyle changes in maintaining improvements in glucose tolerance induced by short‐term energy restriction in obese African Americans with impaired glucose tolerance or type 2 diabetes mellitus. Research Methods and Procedures: An intervention group (n = 45; 47 ± 1 year [mean ± SE]), 105 ± 4 kg; body mass index: 39 ± 1 kg/m²) received an energy‐restricted diet (943 ± 26 kcal/d) for 1 week, followed by a lifestyle program of reduced dietary fat (?125 kcal/d) and increased physical activity (+125 kcal/d) for 1 year. Body weight and plasma concentrations of glucose, insulin, and C‐peptide during an oral glucose tolerance test were measured at baseline, 1‐week, and 4‐month intervals. A control group (n = 24; 48 ± 1 year; 110 ± 5 kg; body mass index: 41 ± 2 kg/m²) underwent these measurements at 4‐month intervals. Results: No changes in weight or glucose tolerance were observed in the control group. The intervention group had significant (p < 0.05) improvements in body weight and glucose tolerance in response to the 1‐week diet, which persisted for 4 months (p < 0.001 vs. control for change in weight). A total of 19 subjects (42%) continued the intervention program for 1 year, with sustained improvements (weight: ?4.6 ± 1.0 kg; p < 0.001 vs. control; oral glucose tolerance test glucose area: ?103 ± 44 mM · min; p < 0.05 vs. control). Discussion: A modest lifestyle program facilitates weight loss and enables improvements in glucose tolerance to be maintained in obese individuals with abnormal glucose tolerance. However, attrition was high, despite the mild nature of the program.     

The Effect of Lateral Decubitus Position on Nocturnal Intraocular Pressure over a Habitual 24-Hour Period in Healthy Adults

Purpose

To investigate the effect of lateral decubitus position (LDP) on nocturnal intraocular pressure (IOP) and the effect of LDP on 24-hour habitual IOP pattern in healthy subjects.

Methods

Intraocular pressure was measured every 2-hours using an Accupen Applanation Tonometer (Accutome, USA). During the diurnal period (7:30 am, 9:30 am, 11:30 am, 1:30 pm, 3:30 pm, 5:30 pm, 7:30 pm, and 9:30 pm), IOP was measured in the sitting position under bright light (500–1000 lux) after the subjects had been seated for 5 min. The nocturnal IOP was measured in the supine position, right LDP, and left LDP, with randomized sequences, under dim light (<10 lux) at 11:30 pm, 1:30 am, 3:30 am, and 5:30 am. The subjects were awakened and maintained each position for 5 min before the measurement. The 24-hour habitual IOP patterns were obtained according to the nocturnal position (supine, right LDP and left LDP) for either eye. P<0.05 was considered to be significant.

Results

Nineteen healthy subjects were included with a mean age of 51.3±5.8 years. During the nocturnal period, a significant IOP difference was found between the dependent eye (the eye on the lower side) of LDP and the supine position, but not for all the nocturnal time points. Over a 24-hour period, the effect of LDP on habitual IOP pattern was not statistically significant, although the mean nocturnal IOP and the diurnal-nocturnal IOP change for the right and the left eye in the LDP pattern was slightly higher than that in the sitting-supine pattern.

Conclusion

Significant nocturnal IOP differences existed between the dependent eye and the supine, but did not occur consistently for all time points. Over a 24-hour period, the effect of LDP on habitual IOP pattern was not statistically significant in healthy subjects.