A new approach for flow-through respirometry measurements in humans

Melanson, Edward L.; Ingebrigtsen, Jan P.; Bergouignan, Audrey; Ohkawara, Kazunori; Kohrt, Wendy M.; Lighton, John R. B.

doi:10.1152/ajpregu.00055.2010

Cited by 55 publications

(60 citation statements)

References 19 publications

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“…EE and respiratory quotient (RQ) were assessed from oxygen (O 2 ) consumption and carbon dioxide (CO 2 ) production (16,44). Gas concentrations were determined from differences in CO 2 and O 2 between entering and exiting air with a fuel-cell-based dual channel O 2 analyzer (FC-2 Oxzilla; Sable Systems International) and two infrared CO 2 analyzers (CA-10 CO 2 analyzers; Sable Systems International) (45). Accuracy and precision of the system is tested monthly using propane combustion tests and average O 2 and CO 2 recoveries during this study were ≥98.0%.…”

Section: Methodsmentioning

confidence: 99%

Impact of insufficient sleep on total daily energy expenditure, food intake, and weight gain

Markwald

Melanson

Smith

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

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Insufficient sleep is associated with obesity, yet little is known about how repeated nights of insufficient sleep influence energy expenditure and balance. We studied 16 adults in a 14-to 15-d-long inpatient study and quantified effects of 5 d of insufficient sleep, equivalent to a work week, on energy expenditure and energy intake compared with adequate sleep. We found that insufficient sleep increased total daily energy expenditure by ∼5%; however, energy intake-especially at night after dinner-was in excess of energy needed to maintain energy balance. Insufficient sleep led to 0.82 ± 0.47 kg (±SD) weight gain despite changes in hunger and satiety hormones ghrelin and leptin, and peptide YY, which signaled excess energy stores. Insufficient sleep delayed circadian melatonin phase and also led to an earlier circadian phase of wake time. Sex differences showed women, not men, maintained weight during adequate sleep, whereas insufficient sleep reduced dietary restraint and led to weight gain in women. Our findings suggest that increased food intake during insufficient sleep is a physiological adaptation to provide energy needed to sustain additional wakefulness; yet when food is easily accessible, intake surpasses that needed. We also found that transitioning from an insufficient to adequate/recovery sleep schedule decreased energy intake, especially of fats and carbohydrates, and led to −0.03 ± 0.50 kg weight loss. These findings provide evidence that sleep plays a key role in energy metabolism. Importantly, they demonstrate physiological and behavioral mechanisms by which insufficient sleep may contribute to overweight and obesity.calorimetry | misalignment | dysregulated eating | deprivation | restriction M ore than 1.4 billion adults, 150 million school-aged children, and 43 million preschool children are estimated to be overweight or obese worldwide (1-3), substantially raising risk for cardiovascular diseases (4) hyperlipidemia (5), diabetes (5, 6), osteoarthritis (6), sleep apnea (7), depression (8), and cancer (9). Excessive food consumption and inadequate physical activity are primary factors contributing to the obesity epidemic. When daily energy intake is in excess of energy expenditure (EE) a state of positive energy balance occurs. Over weeks, months, or years, a small cumulative impact of sustained positive energy balance results in weight gain and obesity (10). Alongside the rise in obesity there has been a decline in the number of individuals who report obtaining the recommended 7-9 h of sleep, with many obtaining less than 6 h per night (11). Insufficient sleep is a risk factor of weight gain and obesity (11-13), yet how insufficient sleep contributes to this risk is unclear. Sleep influences energy metabolism (14, 15), and one function of sleep is to conserve energy (16). Proposed mechanisms that associate insufficient sleep and higher body mass index (BMI) include changes in satiety and hunger hormones altering food intake and changes in EE (17). Insufficient sleep is associated with decreases...

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Section: Methodsmentioning

confidence: 99%

Impact of insufficient sleep on total daily energy expenditure, food intake, and weight gain

Markwald

Melanson

Smith

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

688

603

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“…EE and macronutrient utilization were determined via whole-room indirect calorimetry during days 2-5 (20, 39). Subjects' carbon dioxide (CO 2 ) production and oxygen (O 2 ) consumption were assessed to calculate EE and respiratory quotient (RQ) by measuring gas concentration differences entering and exiting the calorimeter with fuel cell-based dual-channel O 2 analyzers (FC-2 Oxzilla; Sable Systems International) and two infrared CO 2 analyzers (CA-10 CO 2 analyzers; Sable Systems International) (39). Monthly propane combustion tests validated the precision and accuracy of the gas concentration measurements with average recoveries of ∼99%.…”

Section: Methodsmentioning

confidence: 99%

Impact of circadian misalignment on energy metabolism during simulated nightshift work

McHill

Melanson

Higgins

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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Eating at a time when the internal circadian clock promotes sleep is a novel risk factor for weight gain and obesity, yet little is known about mechanisms by which circadian misalignment leads to metabolic dysregulation in humans. We studied 14 adults in a 6-d inpatient simulated shiftwork protocol and quantified changes in energy expenditure, macronutrient utilization, appetitive hormones, sleep, and circadian phase during day versus nightshift work. We found that total daily energy expenditure increased by ∼4% on the transition day to the first nightshift, which consisted of an afternoon nap and extended wakefulness, whereas total daily energy expenditure decreased by ∼3% on each of the second and third nightshift days, which consisted of daytime sleep followed by afternoon and nighttime wakefulness. Contrary to expectations, energy expenditure decreased by ∼12-16% during scheduled daytime sleep opportunities despite disturbed sleep. The thermic effect of feeding also decreased in response to a late dinner on the first nightshift. Total daily fat utilization increased on the first and second nightshift days, contrary to expectations, and carbohydrate and protein utilization were reduced on the second nightshift day. Ratings of hunger were decreased during nightshift days despite decreases in 24-h levels of the satiety hormones leptin and peptide-YY. Findings suggest that reduced total daily energy expenditure during nightshift schedules and reduced energy expenditure in response to dinner represent contributing mechanisms by which humans working and eating during the biological night, when the circadian clock is promoting sleep, may increase the risk of weight gain and obesity.insufficient sleep | melatonin | diet-induced thermogenesis | eating at night | appetite E merging evidence from nonhuman animal models indicates a fundamental interplay between circadian and metabolic physiology (1, 2) with implications for health and disease (3-5). Eating at inappropriate circadian times (e.g., at night) is considered a novel risk factor for weight gain and obesity, yet little research has been conducted in humans on this topic. The circadian time-keeping system in humans modulates energy metabolism so that wakefulness, activity, and food intake are promoted during the solar day and sleep, inactivity, and fasting occur during the solar night (2). With the widespread use of electrical lighting, however, work and social activities are capable of being extended further into the night (6, 7). Being awake during the biological night leads to disturbed physiology and behavior, because it creates a state of desynchrony between the circadian clock and wakefulness-sleep cycle known as circadian misalignment. Circadian misalignment is common in shiftwork. More than 20% of adults in the United States work nontraditional hours (8) and eat some of their meals during the biological night (9), which can increase blood glucose and triacylglycerol levels in response to a high-carbohydrate versus high-fat diet (10) and increase low-dens...

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“…This is particularly relevant to human room calorimetry, where chamber ( = room) volumes of 25 000+ liters are common, together with relatively low flow rates in the 30-80 l/min range. 4 This yields time constants of the order of several hours. Some degree of compensation for the distortion caused by the time constant of the room is obviously essential, and if transient EEs corresponding, for example, to treadmill running, are to be reliably detected within a short time span, that compensation must be extraordinarily fine-tuned via several ingenious methods.…”

Section: Requirements For High Temporal Resolutionmentioning

confidence: 99%

“…In room calorimeters, this is generally accomplished by powerful air circulators. 4 Unfortunately, such vigorous circulation is difficult to achieve within typical model animal chambers, because it carries the risk of greatly accentuating convective heat loss, thus further distorting the metabolic signal. Thus most model animal chambers are not actively, convectively ventilated, and application of mathematical response correction to the resulting data is problematic because of imperfect mixing and slight stratification.…”

Section: Requirements For High Temporal Resolutionmentioning

confidence: 99%

“…It is possible to obtain accurate EE measurements that span long intervals of time, and depending on research focus, such integrative measurements of EE may be sufficient. Examples may include overall energy balance investigations using human room calorimetry [2][3][4] and work on model animals such as mice and rats, where overall, 24 h or scotophase vs photophase EEs are of interest. Other investigators who are interested in fleeting phenomena, such as the EE corresponding to certain activities, or in direct measurements of resting EE (REE), may require higher temporal resolution.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Limitations and requirements for measuring metabolic rates: a mini review

Lighton¹

2017

Eur J Clin Nutr

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Metabolic measurement of humans and model animals is an important aspect of biomedicine. Particularly, in the case of model animals, the limitations of currently widely used metabolic measurement methods are not widely understood. In this mini-review, I explain the theoretical underpinnings of flow-through respirometry as a linear time-invariant system, and the (usually serious) distortions of metabolic data caused by the interaction of chamber volume and flow rate. These can be ameliorated by increasing the flow rate through the chamber, though this is at the expense of the magnitude of the O 2 depletion and CO 2 enhancement signals from which metabolic rates are calculated. If achieved, however, the improvement in temporal response that follows higher flow rates can be marked, and allows confident and accurate measurement of resting and active energy expenditure. Applications of this approach in multiplexing gas signals from multiple cages, and in human room calorimetry, are also discussed.

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A new approach for flow-through respirometry measurements in humans

Cited by 55 publications

References 19 publications

Impact of insufficient sleep on total daily energy expenditure, food intake, and weight gain

Impact of insufficient sleep on total daily energy expenditure, food intake, and weight gain

Impact of circadian misalignment on energy metabolism during simulated nightshift work

Limitations and requirements for measuring metabolic rates: a mini review

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