Biomedical subjects

Andrea C Buchholz

Publications and source records attributed to Andrea C Buchholz.

9 recordsLinked to original sources

PubMed2007

Bioelectrical impedance vs. four-compartment model to assess body fat change in overweight adults.

OBJECTIVE: The Tanita TBF-305 body fat analyzer is marketed for home and clinical use and is based on the principles of leg-to-leg bioelectrical impedance analysis (BIA). Few studies have investigated the ability of leg-to-leg BIA to detect change in percentage fat mass (%FM) over time. Our objective was to determine the ability of leg-to-leg BIA vs. the four-compartment (4C) model to detect small changes in %FM in overweight adults. RESEARCH METHODS AND PROCEDURES: Thirty-eight overweight adults (BMI, 25.0 to 29.9 kg/m2; age, 18 to 44 years; 31 women) participated in a 6-month, randomized, double-blind, placebo-controlled study of a nutritional supplement. Body composition was measured at 0 and 6 months using the Tanita TBF-305 body fat analyzer [using equations derived by the manufacturer (%FM(T-Man)) and by Jebb et al. (%FM(T-Jebb))] and the 4C model (%FM(4C)). RESULTS: Subjects in the experimental group lost 0.9%FM(4C) (p = 0.03), a loss that did not reach significance using leg-to-leg BIA (0.6%FM(T-Man), p = 0.151; 0.6%FM(T-Jebb), p = 0.144). We observed large standard deviations (SDs) in the mean difference in %FM between the 4C model and the Tanita(Manufacturer) (2.5%) and Tanita(Jebb) (2.2%). Ten subjects fell outside +/-1 SD of the mean differences at 0 and 6 months; those individuals were younger and shorter than those within +/-1 SD. DISCUSSION: Leg-to-leg BIA performed reasonably well in predicting decreases in %FM in this group of overweight adults but resulted in wide SDs vs. %FM(4C) in individuals. Cross-sectional determinations of %FM of overweight individuals using leg-to-leg BIA should be interpreted with caution.

Absorptiometry, Photon↗

PubMed2005

Energetics of obesity and weight control: does diet composition matter?

Greater average weight losses (2.5 kg over 12 weeks) have been reported for low-carbohydrate diets (<90 g/day) compared with traditional low-fat (<25% of energy), hypocaloric diets, implying a 233 kcal/day greater energy deficit. It has therefore been suggested that a low-carbohydrate diet may provide a metabolic advantage (an increase in energy expenditure), resulting in a positive effect on weight loss and maintenance. However, a review of studies in which 24-hour energy expenditure was measured did not provide evidence to support a metabolic advantage of low-carbohydrate diets and showed little evidence of a metabolic advantage of high-protein (>25% of energy) diets. Nonetheless, diets high in protein, but either low or modest in carbohydrate, have resulted in greater weight losses than traditional low-fat diets. We speculate that it is the protein, and not carbohydrate, content that is important in promoting short-term weight loss and that this effect is likely due to increased satiety caused by increased dietary protein. It has been suggested that the increased satiety might help persons to be more compliant with a hypocaloric diet and achieve greater weight loss. The current evidence, combined with the need to meet all nutrient requirements, suggests that hypocaloric weight-loss diets should be moderate in carbohydrate (35% to 50% of energy), moderate in fat (25% to 35% of energy), and protein should contribute 25% to 30% of energy intake. More studies of the efficacy of weight-loss and weight-maintenance diets that address protein content are needed. In addition, controlled studies of total energy expenditure or physical activity measured under free-living conditions that directly compare high-protein diets with those containing low and moderate carbohydrate content should also be performed.

Diet, Reducing↗

PubMed2004

Use of air displacement plethysmography in the determination of percentage of fat mass in african american children.

The purpose of this study was to determine the ability of air displacement plethysmography (ADP) to estimate percentage of fat mass (%FM) in African American children. %FM was determined in 21 boys and 13 girls (11.0 +/- 1.4 y, 18.6 +/- 4.2 kg/m(2) [mean +/- SD]) by ADP (using six published densitometric equations) and dual-energy x-ray absorptiometry (DXA). Measures were done within 2 h of one another, in random order. Regardless of equation, %FM(ADP) was significantly correlated with %FM(DXA) (R(2) = 0.67-0.71, all p < 0.001). %FM(ADP) using the equation of Siri (%FM(ADP-Siri) 20.3 +/- 9.0) agreed most closely with %FM(DXA) (20.0 +/- 10.2, difference p = 0.729). Together, surface area artifact and bone mineral content per unit of bone-free fat-free mass accounted for 29% of the variance in the residual between methods. The correlation between %FM(ADP-Siri) and %FM(DXA) was not significant for those <35 kg (n = 10; R(2) = 0.084, p = 0.417). There was a trend toward %FM(ADP-Siri) underestimating %FM(DXA) in girls (-1.46 +/- 3.0%FM; p = 0.103) but not in boys (1.43 +/- 6.4%FM; p = 0.315). Predicted lung volume was 40.1% higher than measured lung volume (p < 0.001). %FM(ADP-Siri) determined using predicted lung volume was 23.5 +/- 8.9, higher than that using measured lung volume (p < 0.001) and higher than %FM(DXA) (p = 0.001). We conclude that in 9- to 14-y-old African American children and provided lung volume is measured, %FM using ADP with Siri's equation approximates that obtained by DXA. Body composition results determined by ADP in children <35 kg should be interpreted with caution.

Absorptiometry, Photon↗

PubMed2004

Is a calorie a calorie?

The aim of this review was to evaluate data regarding potential thermodynamic mechanisms for increased rates of weight loss in subjects consuming diets high in protein and/or low in carbohydrate. Studies that compared weight loss and energy expenditure in adults consuming diets high in protein and/or low in carbohydrate with those in adults consuming diets low in fat were reviewed. In addition, studies that measured the metabolizable energy of proteins, fats, and carbohydrates were reviewed. Diets high in protein and/or low in carbohydrate produced an approximately equal to 2.5-kg greater weight loss after 12 wk of treatment. Neither macronutrient-specific differences in the availability of dietary energy nor changes in energy expenditure could explain these differences in weight loss. Thermodynamics dictate that a calorie is a calorie regardless of the macronutrient composition of the diet. Further research on differences in the composition of weight loss and on the influence of satiety on compliance with energy-restricted diets is needed to explain the observed increase in weight loss with diets high in protein and/or low in carbohydrate.

Dietary Carbohydrates↗

PubMed2004

Energy expenditure in chronic spinal cord injury.

PURPOSE OF REVIEW: Obesity is a common secondary complication of chronic spinal cord injury and is associated with adverse metabolic sequelae. Because positive energy balance is the fundamental cause of obesity, we herein review the current knowledge pertaining to total daily energy expenditure, including resting metabolic rate, the thermic effect of food, and physical activity, in the spinal cord injury population. RECENT FINDINGS: Commonly used equations to predict resting metabolic rate overestimate measured requirements in chronic spinal cord injury by 5-32%. Measured resting metabolic rate is 14-27% lower in persons with spinal cord injury versus those without, due to decreased fat-free mass and sympathetic nervous system activity in this population. However, preliminary evidence suggests that neither the metabolic activity of the fat-free body, nor the obligatory phase of the thermic effect of food is different between those with and without injury. Physical activity levels, especially in those with tetraplegia and complete lesions, are lower than recommended or lower than those of able-bodied persons. SUMMARY: New equations to predict resting metabolic rate should be validated and prospectively tested in a large sample of men and women with complete and incomplete paraplegia and tetraplegia. Whether the facultative phase of the thermic effect of food is different between those with and without SCI remains to be elucidated. Persons with chronic spinal cord injury, and perhaps those with tetraplegia and complete lesions especially, should be encouraged to engage in increased frequency, intensity and/or duration of physical activity. Future research efforts should explore the effects of level and completeness of neurological lesion on resting metabolic rate, thermic effect of food, and physical activity.

Basal Metabolism↗

PubMed2004

The validity of bioelectrical impedance models in clinical populations.

Bioelectrical impedance analysis (BIA) is the most commonly used body composition technique in published studies. Herein we review the theory and assumptions underlying the various BIA and bioelectrical impedance spectroscopy (BIS) models, because these assumptions may be invalidated in clinical populations. Single-frequency serial BIA and discrete multifrequency BIA may be of limited validity in populations other than healthy, young, euvolemic adults. Both models inaccurately predict total body water (TBW) and extracellular water (ECW) in populations with changes in trunk geometry or fluid compartmentalization, especially at the level of the individual. Single-frequency parallel BIA may predict body composition with greater accuracy than the serial model. Hand-to-hand and leg-to-leg BIA models do not accurately predict percent fat mass. BIS may predict ECW, but not TBW, more accurately than single-frequency BIA. Segmental BIS appears to be sensitive to fluid accumulation in the trunk. In general, bioelectrical impedance technology may be acceptable for determining body composition of groups and for monitoring changes in body composition within individuals over time. Use of the technology to make single measurements in individual patients, however, is not recommended. This has implications in clinical settings, in which measurement of individual patients is important.

Journal Article↗

PubMed2003

The use of bioelectric impedance analysis to measure fluid compartments in subjects with chronic paraplegia.

OBJECTIVES: To determine the sensitivity and specificity of body mass index (BMI) as a surrogate marker of obesity in individuals with chronic paraplegia and to validate bioelectric impedance analysis (BIA) as a method of measuring body composition in this group. DESIGN: Cross-sectional study. SETTING: University hospital. PARTICIPANTS: Convenience sample of 31 subjects with paraplegia (19 men, 12 women; mean age, 34.2+/-8.8y) and 62 able-bodied control subjects (30 men, 32 women; mean age, 28.6+/-7.2y). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Total-body water (TBW) by deuterium dilution; extracellular water (ECW) by corrected bromide space. Fat-free mass (FFM)=TBW/.732; fat mass (FM)=weight-FFM. Single-frequency whole-body and segmental BIA, and multifrequency whole-body BIA. RESULTS: BMI had 100% specificity and 20% sensitivity in distinguishing obese from nonobese subjects with paraplegia. TBW was predicted by using the equation: TBW (inL)=2.11-0.1age+3.45sex+.34wt+.28(ht(2)/R)-.086sex x wt(r(2)=.95, standard error of the estimate [SEE]=1.86L, P<.0001). This equation had 81.8% specificity and 68.4% sensitivity. ECW was predicted by using the equation: ECW (in L)=-.025+1.03sex+.187wt+.0041(ht(2)/X(c)) -.033sex x wt (r(2)=.75, SEE=1.62L, P<.0001). Multifrequency BIA offered no greater prediction of TBW or ECW than single-frequency BIA. CONCLUSIONS: BMI has excellent specificity but poor sensitivity in distinguishing obese from nonobese individuals with paraplegia. TBW (and therefore FFM and FM) and ECW can be reasonably well predicted by using single-frequency BIA.

Adult↗

PubMed2003

Physical activity levels are low in free-living adults with chronic paraplegia.

OBJECTIVES: To compare physical activity levels (PALs) of free-living adults with chronic paraplegia with World Health Organization recommendations and to compare energy expenditure between persons with complete vs. incomplete paraplegia. RESEARCH METHODS AND PROCEDURES: Twenty-seven euthyroid adults (17 men and 10 women) with paraplegia (12.5 +/- 9.5 years since onset; 17 with complete lesions and 10 with incomplete lesions) participated in this cross-sectional study. Resting metabolic rate was measured by indirect calorimetry and total daily energy expenditure (TDEE) by heart rate monitoring. PAL was calculated as TDEE/resting metabolic rate. Total body water was measured by deuterium dilution and fat-free mass (FFM) and fat mass (FM) by calculation (FFM = total body water/0.732; FM = weight - FFM). Obesity was defined using the following percentage FM cutoffs: men 18 to 40 years >22% and 41 to 60 years >25%; and women 18 to 40 years >35% and 41 to 60 years >38%. RESULTS: Nineteen subjects (70.4%; 13 men and six women) were obese. Fifteen subjects (56%) engaged in structured physical activity 1.46 +/- 0.85 times during the observation period for a mean of 49.4 +/- 31.0 minutes per session. Despite this, mean PAL of the group was 1.56 +/- 0.34, indicative of limited physical activity. TDEE was 24.6% lower in subjects with complete paraplegia (2072 +/- 505 vs. 2582 +/- 852 kcal/d, p = 0.0372). DISCUSSION: PAL of the group was low, indicating that persons with paraplegia need to engage in increased frequency, intensity, and/or duration of structured physical activity to achieve a PAL >/=1.75 and, thereby, to offset sedentary activities of daily living.

Adolescent↗

PubMed2003

Differences in resting metabolic rate between paraplegic and able-bodied subjects are explained by differences in body composition.

BACKGROUND: Little is known about the relation between body composition and energy metabolism in paraplegia. OBJECTIVE: We investigated the relation between body composition and energy metabolism in healthy paraplegics as compared with able-bodied control subjects. We hypothesized that paraplegics would have lower fat-free mass (FFM), body cell mass (BCM), resting metabolic rate (RMR), and thermic effect of feeding (TEF). DESIGN: This cross-sectional study included 34 control subjects and 28 paraplegics (mean age: 29.1 +/- 7.6 and 33.9 +/- 9.2 y, respectively) with body mass indexes (in kg/m(2)) of 23.5 +/- 1.8 and 24.3 +/- 6.0, respectively. We measured RMR and TEF with indirect calorimetry, total body water with deuterium dilution, and extracellular water with corrected bromide space. We calculated FFM (total body water/0.732) and BCM [(total body water - extracellular water)/0.732)]. RESULTS: FFM was higher in control subjects than in paraplegics (77.2 +/- 7.2% and 69.2 +/- 8.7%, respectively; P = 0.0002), as were BCM (47.4 +/- 6.7% and 35.9 +/- 8.1%, respectively; P < 0.0001) and RMR (7016 +/- 935 and 6159 +/- 954 kJ/d, respectively; P = 0.0007). FFM was the single best predictor of RMR in both groups (r(2) = 0.83 for control subjects and 0.70 for paraplegics, P < 0.0001 for both). RMR adjusted for FFM did not differ significantly between control subjects and paraplegics (6670 +/- 504 and 6588 +/- 501 kJ/d, respectively). TEF also did not differ significantly between control subjects and paraplegics (6.25 +/- 2.2% and 5.53 +/- 1.8% of energy intake, respectively). CONCLUSIONS: FFM, BCM, and RMR, but not obligatory TEF, are lower in paraplegics than in control subjects. RMR does not differ between control and paraplegic subjects after adjustment for FFM, indicating similar metabolic activity in the fat-free compartment of the body.

Adipose Tissue↗