| 1. |
- Speakman, John R., et al.
(författare)
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Total daily energy expenditure has declined over the past three decades due to declining basal expenditure, not reduced activity expenditure
- 2023
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Ingår i: Nature Metabolism. - : NATURE PORTFOLIO. - 2522-5812. ; 5:4, s. 579-588
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Obesity is caused by a prolonged positive energy balance(1,2). Whether reduced energy expenditure stemming from reduced activity levels contributes is debated(3,4). Here we show that in both sexes, total energy expenditure (TEE) adjusted for body composition and age declined since the late 1980s, while adjusted activity energy expenditure increased over time. We use the International Atomic Energy Agency Doubly Labelled Water database on energy expenditure of adults in the United States and Europe (n = 4,799) to explore patterns in total (TEE: n = 4,799), basal (BEE: n = 1,432) and physical activity energy expenditure (n = 1,432) over time. In males, adjusted BEE decreased significantly, but in females this did not reach significance. A larger dataset of basal metabolic rate (equivalent to BEE) measurements of 9,912 adults across 163 studies spanning 100 years replicates the decline in BEE in both sexes. We conclude that increasing obesity in the United States/Europe has probably not been fuelled by reduced physical activity leading to lowered TEE. We identify here a decline in adjusted BEE as a previously unrecognized factor.
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| 2. |
- Dugas, Lara R., et al.
(författare)
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Obesity-related metabolite profiles of black women spanning the epidemiologic transition
- 2016
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Ingår i: Metabolomics. - New York : Springer-Verlag New York. - 1573-3882 .- 1573-3890. ; 12:3
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Tidskriftsartikel (refereegranskat)abstract
- In developed countries, specific metabolites have been associated with obesity and metabolic diseases, e.g. type 2 diabetes. It is unknown whether a similar profile persists across populations of African-origin, at increased risk for obesity and related diseases. In a cross-sectional study of normal-weight and obese black women (33.3 +/- 6.3 years) from the US (N = 69, 65 % obese), South Africa (SA, N = 97, 49 % obese) and Ghana (N = 82, 33 % obese) serum metabolite profiles were characterized via gas chromatography-time of flight/mass spectrometry. In US and SA women, BMI correlated with branched-chain and aromatic amino acids, as well as dopamine and aminoadipic acid. The relationship between BMI and lipid metabolites differed by site; BMI correlated positively with palmitoleic acid (16: 1) in the US; negatively with stearic acid (18: 0) in SA, and positively with arachidonic acid (20: 4) in Ghana. BMI was also positively associated with sugar-related metabolites in the US; i.e. uric acid, and mannitol, and with glucosamine, glucoronic acid and mannitol in SA. While we identified a common amino acid metabolite profile associated with obesity in black women from the US and SA, we also found site-specific obesity-related metabolites suggesting that the local environment is a key moderator of obesity.
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| 3. |
- Kaviani, Sepideh, et al.
(författare)
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Determining the Accuracy and Reliability of Indirect Calorimeters Utilizing the Methanol Combustion Technique
- 2018
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Ingår i: Nutrition in Clinical Practice. - : Wiley. - 0884-5336. ; 33:2, s. 206-216
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Tidskriftsartikel (refereegranskat)abstract
- Background: Several indirect calorimetry (IC) instruments are commercially available, but comparative validity and reliability data are lacking. Existing data are limited by inconsistencies in protocols, subject characteristics, or single-instrument validation comparisons. The aim of this study was to compare accuracy and reliability of metabolic carts using methanol combustion as the cross-laboratory criterion. Methods: Eight 20-minute methanol burn trials were completed on 12 metabolic carts. Respiratory exchange ratio (RER) and percent O2 and CO2 recovery were calculated. Results: For accuracy, 1 Omnical, Cosmed Quark CPET (Cosmed), and both Parvos (Parvo Medics trueOne 2400) measured all 3 variables within 2% of the true value; both DeltaTracs and the Vmax Encore System (Vmax) showed similar accuracy in measuring 1 or 2, but not all, variables. For reliability, 8 instruments were shown to be reliable, with the 2 Omnicals ranking best (coefficient of variation [CV] < 1.26%). Both Cosmeds, Parvos, DeltaTracs, 1 Jaeger Oxycon Pro (Oxycon), Max-II Metabolic Systems (Max-II), and Vmax were reliable for at least 1 variable (CV ≤ 3%). For multiple regression, humidity and amount of combusted methanol were significant predictors of RER (R2 = 0.33, P <.001). Temperature and amount of burned methanol were significant predictors of O2 recovery (R2 = 0.18, P <.001); only humidity was a predictor for CO2 recovery (R2 = 0.15, P <.001). Conclusions: Omnical, Parvo, Cosmed, and DeltaTrac had greater accuracy and reliability. The small number of instruments tested and expected differences in gas calibration variability limits the generalizability of conclusions. Finally, humidity and temperature could be modified in the laboratory to optimize IC conditions.
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| 4. |
- Kaviani, Sepideh, et al.
(författare)
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Determining the Accuracy and Reliability of Indirect Calorimeters Utilizing the Methanol Combustion Technique
- 2017
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Ingår i: The FASEB Journal. - 0892-6638 .- 1530-6860. ; 31:S1
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Tidskriftsartikel (refereegranskat)abstract
- ObjectiveThere are several indirect calorimetry (IC) instruments commercially available but validity and reliability data is lacking. Site-to-site inconsistencies in protocols and subject characteristics, and comparisons to a “gold standard” instrument or method which may no longer be accurate enough, have put restraints on drawing conclusions about instruments' performance.PurposeTo compare the accuracy and reliability of different metabolic carts using the methanol combustion technique as the criterion measure.MethodsA total of eight, 20-minute methanol burn trials were completed on 12 metabolic carts (2 Cosmed Quark CPET, 2 DeltaTrac II, 2 Parvo Medics TrueOne 2400, 2 Iaeger Oxycon Pros, 2 Omnicals, a Vmax Encore, and a Max-II Metabolic System) at 11 international study sites. Methanol tests were performed at 0700, 1000, 1300, and 1600 hours on 2 consecutive days. Respiratory Exchange Ratio (RER) and percent (%) recovery of O2 and CO2 were calculated after each test.ResultsAccuracy – 1 Omnical, Cosmed, and Parvo were accurate in measuring RER and % recovery O2, while 1 DeltaTrac was also accurate for % recovery O2. The same Cosmed and Parvo, and the other DeltaTrac were accurate in measuring % recovery CO2. Reliability – 8 instruments were shown to be reliable with the two Omnicals ranking best based on the smallest coefficient of variation (CV) (all CV(s) 1.26%). Both Cosmeds, Parvos, DeltaTracs and 1 Vmax were the reliable instruments for at least one variable (CV(s) 3%). Multiple Regression– Humidity, amount of methanol combusted, and temperature were tested as predictors of IC outcomes. Humidity and amount of combusted methanol were significant predictors of RER (F (2, 60) =10.91, p<0.001, R2=0.33). Temperature and amount of burned methanol were significant predictors of % recovery O2 (F (2, 60) =8.32, p<0.001, R2=0.18) while only humidity was a predictor for % recovery CO2 (F (1, 61) =21.10, p<0.001, R2=0.15).ConclusionOmnical, Cosmed, and Parvo showed superior accuracy and reliability; however, accuracy was only found at one of two study sites. Exogenous factors such as humidity and temperature may be influencing instrument performance and could be modified in the lab to optimize IC conditions.
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