Continuous fat oxidation in acetyl CoA carboxylase 2 knockout mice increases total energy expenditure, reduces fat mass, and improves insulin sensitivity

Abstract The effect of aging on β-adrenergically mediated substrate utilization was investigated in nine young (25.2 ± 1.7 yr old) and eight older males (52.9 ± 2.1 yr old), matched for body weight and body composition. In a first experiment, the nonselectiveβ -agonist isoprenaline (ISO) was infused in increasing standardized doses, and during each infusion period energy expenditure and substrate utilization were determined by indirect calorimetry. In a second experiment, forearm skeletal muscle metabolism was studied during a standardized infusion dose of ISO (19 ng/kg fat-free mass·min). During β-adrenergic stimulation there was an increased carbohydrate oxidation (at an ISO infusion dose of 24 ng/kg fat-free mass·min, 31% vs. 21% of total energy expenditure; P < 0.05) and a decreased fat oxidation (51 vs. 62 of total energy expenditure; P < 0.05) in older compared to young subjects. Skeletal muscle lactate release significantly increased in the older subjects (from −175 ± 32 to −366 ± 66 nmol/100 mL forearm tissue·min), whereas there was no change in young subjects (from− 32 ± 21 to 23 ± 57 nmol/100 mL forearm tissue·min; interaction group × ISO, P < 0.01). Additionally, there was a tendency toward a blunted ISO-induced increase in nonesterified fatty acid uptake in the older subjects (interaction group × ISO, P = 0.062). Thus, middle-aged subjects have a blunted ability to oxidize fat during β-adrenergic stimulation compared to young subjects. This diminished fat oxidation may be an important etiological factor in the age-related increase in body fatness and obesity by favoring fat storage above oxidation.

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PP198-MON CHANGES IN THE TOTAL ENERGY EXPENDITURE WITH MAINTENANCE OF FREE FAT MASS, AFTER A PHYSICAL ACTIVITY AND NUTRITIONAL PROGRAM, IN OVERWEIGHT AND OBESE PATIENTS: METABOLIC MONITORING OF PHYSICAL ACTIVITY

Clinical Nutrition Supplements ◽

10.1016/s1744-1161(11)70488-4 ◽

2011 ◽

Vol 6 (1) ◽

pp. 189

Author(s):

J.M. Garcia-Almeida ◽

J. Garcia-Aleman ◽

J. Ruiz-Nava ◽

H. Saracho-dominguez ◽

G. Casado-Fernandez ◽

...

Keyword(s):

Physical Activity ◽

Energy Expenditure ◽

Total Energy ◽

Fat Mass ◽

Total Energy Expenditure ◽

Obese Patients ◽

Metabolic Monitoring

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Ingested Fat Oxidation Contributes 8% of 24-h Total Energy Expenditure in Moderately Obese Subjects

Journal of Nutrition ◽

10.1093/jn/135.9.2159 ◽

2005 ◽

Vol 135 (9) ◽

pp. 2159-2165 ◽

Cited By ~ 11

Author(s):

Bakary J. Sonko ◽

Paul V. Fennessey ◽

Joseph E. Donnelly ◽

Daniel Bessesen ◽

Teresa A. Sharp ◽

...

Keyword(s):

Energy Expenditure ◽

Total Energy ◽

Fat Oxidation ◽

Total Energy Expenditure ◽

Obese Subjects

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Total energy expenditure is repeatable in adults but not associated with short-term changes in body composition

Nature Communications ◽

10.1038/s41467-021-27246-z ◽

2022 ◽

Vol 13 (1) ◽

Author(s):

Rebecca Rimbach ◽

Yosuke Yamada ◽

Hiroyuki Sagayama ◽

Philip N. Ainslie ◽

Lene F. Anderson ◽

...

Keyword(s):

Body Composition ◽

Risk Factor ◽

Weight Gain ◽

Energy Expenditure ◽

Total Energy ◽

Fat Mass ◽

Total Energy Expenditure ◽

Fat Free Mass ◽

Time Interval ◽

Time Intervals

AbstractLow total energy expenditure (TEE, MJ/d) has been a hypothesized risk factor for weight gain, but repeatability of TEE, a critical variable in longitudinal studies of energy balance, is understudied. We examine repeated doubly labeled water (DLW) measurements of TEE in 348 adults and 47 children from the IAEA DLW Database (mean ± SD time interval: 1.9 ± 2.9 y) to assess repeatability of TEE, and to examine if TEE adjusted for age, sex, fat-free mass, and fat mass is associated with changes in weight or body composition. Here, we report that repeatability of TEE is high for adults, but not children. Bivariate Bayesian mixed models show no among or within-individual correlation between body composition (fat mass or percentage) and unadjusted TEE in adults. For adults aged 20–60 y (N = 267; time interval: 7.4 ± 12.2 weeks), increases in adjusted TEE are associated with weight gain but not with changes in body composition; results are similar for subjects with intervals >4 weeks (N = 53; 29.1 ± 12.8 weeks). This suggests low TEE is not a risk factor for, and high TEE is not protective against, weight or body fat gain over the time intervals tested.

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Does skeletal muscle carnitine availability influence fuel selection during exercise?

Proceedings of The Nutrition Society ◽

10.1017/s0029665117003937 ◽

2017 ◽

Vol 77 (1) ◽

pp. 11-19 ◽

Cited By ~ 8

Author(s):

Francis B. Stephens

Keyword(s):

Skeletal Muscle ◽

Energy Expenditure ◽

Total Energy ◽

Exercise Intensity ◽

Human Subjects ◽

Maximal Oxygen Consumption ◽

Fat Oxidation ◽

Total Energy Expenditure ◽

Fuel Selection

Fat and carbohydrate are the major fuel sources utilised for oxidative, mitochondrial ATP resynthesis during human skeletal muscle contraction. The relative contribution of these two substrates to ATP resynthesis and total energy expenditure during exercise can vary substantially, and is predominantly determined by fuel availability and exercise intensity and duration. For example, the increased ATP demand that occurs with an increase in exercise intensity is met by increases in both fat and carbohydrate oxidation up to an intensity of approximately 60–70 % of maximal oxygen consumption. When exercise intensity increases beyond this workload, skeletal muscle carbohydrate utilisation is accelerated, which results in a reduction and inhibition of the relative and absolute contribution of fat oxidation to total energy expenditure. However, the precise mechanisms regulating muscle fuel selection and underpinning the decline in fat oxidation remain unclear. This brief review will primarily address the theory that a carbohydrate flux-mediated reduction in the availability of muscle carnitine to the mitochondrial enzyme carnitine palmitoyltransferase 1, a rate-limiting step in mitochondrial fat translocation, is a key mechanism for the decline in fat oxidation during high-intensity exercise. This is discussed in relation to recent work in this area investigating fuel metabolism at various exercise intensities and taking advantage of the discovery that skeletal muscle carnitine content can be nutritionally increased in vivo in human subjects.

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