A continuous analyzer for monitoring respiratory gases and expired radioactivity in clinical studies

Long, Calvin L.; Carlo, M.A.; Schaffel, Neal A.; Schiller, William R.; Blakemore, William S.; Spencer, Jordan L.; Broell, J.

doi:10.1016/0026-0495(79)90102-1

Cited by 27 publications

(3 citation statements)

References 6 publications

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“…The oxygen analyzer is sensitive to +2 ml 02/min out of 242 ml 02/min, and the carbon dioxide analyzer is sensitive to +2 ml C02/min out of 218 ml C02/min. This indicates that, in the calibration procedure, the measured rate of oxygen consumption or carbon dioxide production differs from the actual amount by less than 1% for each instrument (12 (14).…”

Section: Methodsmentioning

confidence: 99%

Metabolic predictors of obesity. Contribution of resting energy expenditure, thermic effect of food, and fuel utilization to four-year weight gain of post-obese and never-obese women.

Weinsier¹,

Nelson²,

Hensrud³

et al. 1995

J. Clin. Invest.

148

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This prospective study was designed to identify abnormalities of energy expenditure and fuel utilization which distinguish post-obese women from never-obese controls. 24 moderately obese, postmenopausal, nondiabetic women with a familial predisposition to obesity underwent assessments of body composition, fasting and postprandial energy expenditure, and fuel utilization in the obese state and after weight loss (mean 12.9 kg) to a post-obese, normal-weight state. The post-obese women were compared with 24 never-obese women of comparable age and body composition. Four years later, without intervention, body weight was reassessed in both groups. Results indicated that all parameters measured in the post-obese women were similar to the never-obese controls: mean resting energy expenditure, thermic effect of food, and fasting and postprandial substrate oxidation and insulinglucose patterns. Four years later, post-obese women regained a mean of 10.9 kg while control subjects remained lean (mean gain 1.7 kg) (P < 0.001 between groups). Neither energy expenditure nor fuel oxidation correlated with 4-yr weight changes, whereas self-reported physical inactivity was associated with greater weight regain.The data suggest that weight gain in obesity-prone women may be due to maladaptive responses to the environment, such as physical inactivity or excess energy intake, rather than to reduced energy requirements. (J. Clin. Invest. 1995. 95:980-985.)

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Section: Methodsmentioning

confidence: 99%

Metabolic predictors of obesity. Contribution of resting energy expenditure, thermic effect of food, and fuel utilization to four-year weight gain of post-obese and never-obese women.

Weinsier¹,

Nelson²,

Hensrud³

et al. 1995

J. Clin. Invest.

148

View full text Add to dashboard Cite

show abstract

“…After subjects had fasted overnight, blood was drawn for measurement of serum triiodothyronine (T 3 ) and reverse T 3 (rT 3 ), which were analyzed by 125 I radioimmunoassay (16). At least 2 h after venipuncture and after subjects had rested an additional 30 min in the supine position, RMR was measured over a 30-min period by indirect calorimetry using a thermoplastic ventilatedhood canopy system (17). Body composition was determined by underwater weighing (18) with residual lung volume obtained using the closed-circuit oxygen-dilution method (19).…”

Section: Study Measuresmentioning

confidence: 99%

Do adaptive changes in metabolic rate favor weight regain in weight-reduced individuals? An examination of the set-point theory

Weinsier

Nagy

Hunter

et al. 2000

The American Journal of Clinical Nutrition

182

144

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Background: Obese persons generally regain lost weight, suggesting that adaptive metabolic changes favor return to a preset weight. Objective: Our objective was to determine whether adaptive changes in resting metabolic rate (RMR) and thyroid hormones occur in weight-reduced persons, predisposing them to longterm weight gain. Design: Twenty-four overweight, postmenopausal women were studied at a clinical research center in four 10-d study phases: the overweight state (phase 1, energy balance; phase 2, 3350 kJ/d) and after reduction to a normal-weight state (phase 3, 3350 kJ/d; phase 4, energy balance). Weight-reduced women were matched with 24 never-overweight control subjects. After each study phase, assessments included RMR (by indirect calorimetry), body composition (by hydrostatic weighing), serum triiodothyronine (T 3 ), and reverse T 3 (rT 3 ). Body weight was measured 4 y later, without intervention. Results: Body composition-adjusted RMR and T 3 :rT 3 fell during acute (phase 2) and chronic (phase 3) energy restriction (P < 0.01), but returned to baseline in the normal-weight, energybalanced state (phase 4; mean weight loss: 12.9 ± 2.0 kg). RMR among weight-reduced women (4771 ± 414 kJ/d) was not significantly different from that in control subjects (4955 ± 414 kJ/d; P = 0.14), and lower RMR did not predict greater 4-y weight regain (r = 0.27, NS). Conclusions: Energy restriction produces a transient hypothyroid-hypometabolic state that normalizes on return to energybalanced conditions. Failure to establish energy balance after weight loss gives the misleading impression that weight-reduced persons are energy conservative and predisposed to weight regain. Our findings do not provide evidence in support of adaptive metabolic changes as an explanation for the tendency of weight-reduced persons to regain weight.Am J Clin Nutr 2000;72:1088-94.

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“…Prior to REE measurements, subjects were fasted for 10-12 hours. Oxygen consumption (VO2) and carbon dioxide production (VCO2) were measured for 30 minutes using a thermoplastic ventilatedhood canopy system [13]. Per instructions of the manufacturer, calibrations were performed prior to each test.…”

Section: Resting Energy Expenditurementioning

confidence: 99%

Ability of the Harris-Benedict formula to predict energy requirements differs with weight history and ethnicity

et al. 2007

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The objective of this study was to assess the effects of weight history status and ethnicity on the ability of the Harris Benedict (HB) formula to: 1) predict measured resting energy expenditure (REE), and, 2) accurately estimate energy needs over a 2-week test period. Subjects were never-overweight (BMI ≤ 25 kg/m 2 , n=47), overweight (BMI 27-30 kg/m 2 , n=170), and weight-reduced (BMI ≤ 25 kg/m 2 , n=51) healthy, adult African-American (AA) and Caucasian (C) women. Food was provided for 2 weeks at an energy level calculated using the HB formula multiplied by a 1.35 activity factor. After 2 weeks, weight, REE (by indirect calorimetry), and body composition (by dual-energy X-ray absorptiometry) were assessed. Data were analyzed using 2-way ANOVA at p<0.05 significance. The HB formula overestimated REE 1) in each weight history group (by 160 ±125 kcals among never-overweight, 295 ±189 kcal among overweight, and 105 ±135 among weight-reduced) such that there was a group effect on overestimation (P<0.001) and 2) between ethnicities, with a greater overestimation in AA vs. C (P<0.001). There was a significant effect of weight history group on weight change (P<0.001) over 2-weeks, such that weight-reduced women gained more weight than the other two groups (P<0.05). In conclusion, the ability of the HB formula to estimate REE differed with weight history status and ethnicity. The accuracy of the HB formula to predict dietary energy needs was affected by weight history status. These results suggest that formulas used to calculate energy needs should take into account weight history and ethnicity.

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A continuous analyzer for monitoring respiratory gases and expired radioactivity in clinical studies

Cited by 27 publications

References 6 publications

Metabolic predictors of obesity. Contribution of resting energy expenditure, thermic effect of food, and fuel utilization to four-year weight gain of post-obese and never-obese women.

Metabolic predictors of obesity. Contribution of resting energy expenditure, thermic effect of food, and fuel utilization to four-year weight gain of post-obese and never-obese women.

Do adaptive changes in metabolic rate favor weight regain in weight-reduced individuals? An examination of the set-point theory

Ability of the Harris-Benedict formula to predict energy requirements differs with weight history and ethnicity

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