The 24-hour respiratory quotient predicts energy intake and changes in body mass

Longo, Kenneth A.; Charoenthongtrakul, Soratree; Giuliana, Derek J.; Govek, Elizabeth; McDonagh, Thomas; DiStefano, Peter S.; Geddes, Brad J.

doi:10.1152/ajpregu.00476.2009

Cited by 43 publications

(49 citation statements)

References 36 publications

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“…2A). Administration of HFD and the consequent development of obesity are associated with a decrease in RER due to fatty acid oxidation (20). This change was evident when control mice received HFD.…”

Section: Il-15r␣mentioning

confidence: 95%

IL-15Rα is a determinant of muscle fuel utilization, and its loss protects against obesity

Loro

Seifert

Moffat

et al. 2015

American Journal of Physiology-Regulatory, Integrative and Comp

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is the widely expressed primary binding partner for IL-15. Because of the wide distribution in nonlymphoid tissues like skeletal muscle, adipose, or liver, IL-15/IL-15R␣ take part in physiological and metabolic processes not directly related to immunity. In fast muscle, lack of IL-15R␣ promotes an oxidative switch, with increased mitochondrial biogenesis and fatigue resistance. These effects are predicted to reproduce some of the benefits of exercise and, therefore, improve energy homeostasis. However, the direct effects of IL-15R␣ on metabolism and obesity are currently unknown. We report that mice lacking IL-15R␣ (IL-15R␣ Ϫ/Ϫ ) are resistant to diet-induced obesity (DIO). High-fat diet-fed IL-15R␣ Ϫ/Ϫ mice have less body and liver fat accumulation than controls. The leaner phenotype is associated with increased energy expenditure and enhanced fatty acid oxidation by muscle mitochondria. Despite being protected against DIO, IL-15R␣ Ϫ/Ϫ are hyperglycemic and insulin-resistant. These findings identify novel roles for IL-15R␣ in metabolism and obesity.interleukin-15 receptor alpha; diet-induced obesity; muscle; fatty acid oxidation; fatigue recovery; glucose homeostasis ACCUMULATION OF EXCESSIVE body fat is a physiological consequence of unnecessary caloric intake. With greater worldwide food production, often the caloric intake largely exceeds the physiological energy requirements, and as a result, the obesity pandemic is growing at alarming rates in both developed and developing countries (21,47). Apart from the role of environmental factors, particularly an energy-dense diet and sedentary lifestyle, obesity also has important genetic determinants that have been conserved across species. Identifying the molecular mechanisms regulating metabolic efficiency (the capacity to convert energy intake into storable energy forms) is of great interest because of the low success in using caloric restriction as a means to manage obesity. Indeed, a number of pathways have been recently identified that reduce the extent of dietinduced obesity (DIO) by decreasing metabolic efficiency rather than energy input (8,10,11,43,56,59,60). Targeting these pathways with pharmacological approaches may also have the advantage of reproducing some of the benefits normally associated with physical exercise. Together with caloric restriction, exercise is a mainstay of a healthy life style and contributes to the control of metabolic efficiency. In addition to converting energy into movement, exercise increases the rates of lipolysis and fat oxidation, promotes heat dissipation (49, 53), and causes long-term changes in the expression of numerous genes, including IL-15R␣/IL-15 (55).IL-15 and its primary binding partner IL-15R␣ have emerged as important regulators of cell functions in both lymphoid and nonlymphoid tissues. Their transcripts are detectable in a variety of tissues, including skeletal muscle, liver, or adipose (http://biogps.org/#gotoϭwelcome). Some of the proposed noncanonical roles of IL-15/IL-15R␣ signaling are mediating anabolic...

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Section: Il-15r␣mentioning

confidence: 95%

IL-15Rα is a determinant of muscle fuel utilization, and its loss protects against obesity

Loro

Seifert

Moffat

et al. 2015

American Journal of Physiology-Regulatory, Integrative and Comp

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“…These are surprisingly high compared with the previous observations in mice, other mammals, and humans (e.g., see Refs. 6,10,and 19). RQ Ͼ1.00 cannot be observed unless net neolipogenesis is occurring.…”

mentioning

confidence: 98%

Validity of doubly labeled water in obese subjects: questioning the validity of any technique requires an indisputable accuracy of the reference method

Yamada

Blanc

Nishida

et al. 2013

American Journal of Physiology-Endocrinology and Metabolism

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TO THE EDITOR: In a recent article, Guidotti et al. (5) reported that the nutritional and body adiposity status affects the dilution space ratio (N d /N o ) between deuterium ( 2 H) and 18 O and validity of CO 2 production (rCO 2 ) by the doubly labeled water (DLW) method in mice. Their data disagree with those reported by many independent research groups.First, theirs is the only validation study of DLW ever to find that the two-pool model fits the data better than a single-pool model in small animals (Ͻ1 kg), and thus we have to question the general validity of their findings. Speakman (21) listed 22 validation studies of the DLW method for mammals and 18 for birds and strongly concluded that a single-pool model fits the data better in small animals (Ͻ1 kg). This conclusion was supported by more recent studies that also found that the one-pool model [see Eq. 7.17 in Speakman (21)] fits the data better than two-pool evaluations. These include 1) Visser and Schekkerman (26) and Visser et al. (25), who examined the DLW method in several birds (black-tailed godwit, northern lapwing, and Japanese quail), with relative growth rates ranging from Ϫ16.9 to ϩ23.8% on day 1 (27.7-294.4 g) against the rCO 2 measured by indirect calorimetry (rCO 2IC ); 2) Blanc et al. (1) in rats (290 Ϯ 27 g) during isolation and simulated microgravity against rCO 2IC ; 3) Van Trigt et al. (24) in Japanese quail (ϳ250 g) at different water fluxes against rCO 2IC ; 4) Gessaman et al. (3a) in growing poultry chicks against rCO 2IC ; 5) Speakman and Król (22) in field voles (ϳ38 g) at 8°C against metabolizable energy intake; and 6) Shirai et al. (20) in rhinoceros auklet (ϳ530 g) against rCO 2IC . Therefore, the Guidotti et al. (5) data sit at odds with all prior validation studies of the method, yet surprisingly, they did not mention this, test, or even discuss possible reasons for this discrepancy.We are concerned about the accuracy of the indirect calorimetry data reported by Guidotti et al. (5). They reported that the 3-day respiratory quotients (RQ) were 1.01 Ϯ 0.01 (means Ϯ SE) and 0.92 or 0.89 Ϯ 0.01 for regular laboratory chow (13% fat, 63% starch and 24% protein) and high-fat diet (45% fat, 18% starch, 13% sucrose, 24% protein), respectively. These are surprisingly high compared with the previous observations in mice, other mammals, and humans (e.g., see Refs. 6,10,and 19). RQ Ͼ1.00 cannot be observed unless net neolipogenesis is occurring. When the food quotient (FQ), defined as the ideal diet-specific ratio of V CO 2 to V O 2 , was calculated for each diet using the equation (0.835 ϫ %protein) ϩ (1.0 ϫ %carbohy-drate) ϩ (0.71 ϫ %fat) (9), the FQs were 0.92 and 0.83 for the regular chow and high-fat diet, respectively. Therefore, there is a large discrepancy between the RQ and FQ, which is particularly surprising after 6 wk of treatment, and therefore, these discrepancies raise doubts over the validity of the indirect calorimetry performed. There is no detail in the article of the methods by which the indirect calorimetry syste...

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“…ACCEPTED MANUSCRIPT 8 The effect of tramadol on palatable food intake and body weight was not reported previously. Since this effect is not characteristic for μ-opiate agonists, other neurochemical processes may also be involved, for example tramadol is known to inhibit noradrenaline and serotonin reuptake [20].…”

Section: Accepted Manuscriptmentioning

confidence: 80%

“…These processes affect the outcome of a hypocaloric diet targeting weight loss oppositely: decreased RER is a marker of increased fat catabolism [7,8], while reduced EE decreases the efficacy of dieting [9,10].…”

Section: Accepted Manuscript 1 Introductionmentioning

confidence: 99%

Differential regulation of metabolic parameters by energy deficit and hunger

Kitka¹,

Tuza²,

Varga³

et al. 2015

Metabolism

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The 24-hour respiratory quotient predicts energy intake and changes in body mass

Cited by 43 publications

References 36 publications

IL-15Rα is a determinant of muscle fuel utilization, and its loss protects against obesity

IL-15Rα is a determinant of muscle fuel utilization, and its loss protects against obesity

Validity of doubly labeled water in obese subjects: questioning the validity of any technique requires an indisputable accuracy of the reference method

Differential regulation of metabolic parameters by energy deficit and hunger

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