scholarly journals Free and esterified fatty acid and cholesterol synthesis in adult malesand its effect on the doubly-labelled water method

2000 ◽  
Vol 83 (3) ◽  
pp. 227-234 ◽  
Author(s):  
P. Haggarty ◽  
P. Shetty ◽  
S. Thangam ◽  
S. Kumar ◽  
A. Kurpad ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Free Fatty Acid ◽  
Energy Balance ◽  
Cholesterol Synthesis ◽  
Western Diet ◽  
Lipid Classes ◽  
High Rate ◽  
Whole Body ◽  
Doubly Labelled Water ◽  
Typical Western Diet

The purpose of the present study was to estimate whole-body fatty acid and cholesterol synthesis in weight-stable adults and to determine the likely effect on the doubly-labelled water (DLW) method for measuring energy expenditure. Synthesis was measured by 2H incorporation over 14 d in six adult males in approximate energy balance following noradrenaline infusion to maximize mobilization of free fatty acid from adipose tissue. The inter-individual variation in synthesis rates was large and in one subject the proportion of free fatty acid synthesized was ten times that of the mean of the rest of the group; the fasting concentration of esterified fatty acid in this subject was five times that of the rest of the group indicating likely violation of the assumptions underlying the calculation of whole-body synthesis. After 14 d of labelling in the other five subjects, 0·9 (SEM 0·3) % OF THE CIRCULATING FREE FATTY ACID, 9·3 (sem 3·0) % of the esterified fatty acid, 14·6 (sem 2·4) % of the free cholesterol and 28·3 (sem 3·7) % of esterified cholesterol had been synthesized de novo. A high rate of synthesis correlated with a low pre-dose 2H abundance both within and between lipid classes suggesting that natural 2H abundance variations in some lipid classes may be used to determine their metabolic origin. Whole-body synthetic rates were 8 g/d for fatty acid and 0·3–0·5 g/d for cholesterol. These values correspond to very small errors on DLW-derived estimates of CO2 production; -2·5 litres/d for fatty acid and -0·1 to -0·2 litres/d for cholesterol. These results, obtained in subjects typically consuming a diet with a lower fat and cholesterol content that the typical Western diet, suggest that the DLW method is unlikely to be affected by fatty acid and cholesterol synthesis in subjects in energy balance consuming a typical Western diet.

Dose-dependent effect of insulin on plasma free fatty acid turnover and oxidation in humans

1990 ◽  
Vol 259 (5) ◽  
pp. E736-E750 ◽  
Author(s):  
R. C. Bonadonna ◽  
L. C. Groop ◽  
K. Zych ◽  
M. Shank ◽  
R. A. DeFronzo
Keyword(s):  
Fatty Acid ◽  
Free Fatty Acid ◽  
Lipid Oxidation ◽  
Plasma Insulin ◽  
Plasma Free Fatty Acid ◽  
Whole Body ◽  
Glucose Disposal ◽  
Body Lipid ◽  
Plasma Ffa ◽  
Dose Dependent

Methodology for measuring plasma free fatty acid (FFA) turnover/oxidation with [1–14C]palmitate was tested in normal subjects. In study 1, two different approaches (720-min tracer infusion without prime vs. 150-min infusion with NaH14CO3 prime) to achieve steady-state conditions of 14CO2 yielded equivalent rates of plasma FFA turnover/oxidation. In study 2, during staircase NaH14CO3 infusion, calculated rates of 14CO2 appearance agreed closely with NaH14CO3 infusion rates. In study 3, 300-min euglycemic insulin clamp documented that full biological effect of insulin on plasma FFA turnover/oxidation was established within 60–120 min. In study 4, plasma insulin concentration was raised to 14 +/- 2, 23 +/- 2, 38 +/- 2, 72 +/- 5, and 215 +/- 10 microU/ml. A dose-dependent insulin suppression of plasma FFA turnover/oxidation was observed. Plasma FFA concentration correlated positively with plasma FFA turnover/oxidation in basal and insulinized states. Total lipid oxidation (indirect calorimetry) was significantly higher than plasma FFA oxidation in the basal state, suggesting that intracellular lipid stores contributed to whole body lipid oxidation. Hepatic glucose production and total glucose disposal showed the expected dose-dependent suppression and stimulation, respectively, by insulin. In conclusion, insulin regulation of plasma FFA turnover/oxidation is maximally manifest at low physiological plasma insulin concentrations, and in the basal state a significant contribution to whole body lipid oxidation originates from lipid pool(s) that are different from plasma FFA.

ACETATE AND FREE FATTY ACID METABOLISM IN THE FAT-TAILLED SHEEP

1984 ◽  
Vol 64 (5) ◽  
pp. 244-245 ◽  
Author(s):  
J. G. VAN DER WALT ◽  
A. MARAIS ◽  
S. CAMPBELL ◽  
J. M. GOODEN
Keyword(s):  
Fatty Acid ◽  
Free Fatty Acid ◽  
Key Words ◽  
Fatty Acid Metabolism ◽  
Acid Metabolism ◽  
Carbon Flow ◽  
Whole Body ◽  
Free Fatty Acid Metabolism ◽  
Ad Libitum ◽  
Ad Libitum Feeding

Two-thirds of all acetate to FFA conversion takes place in the hindquarter of Karakul lambs fed ad libitum. An amount equivalent to two-thirds of this net FFA production is taken up by the hind-quarter. Half ad libitum feeding resulted in halving the whole-body acteate turnover, reversing the direction of carbon flow from FFA to acetate and doubling the FFA turnover, chiefly by mobilizing tail fat. Resumption of ad libitum feeding reversed the process, without synthesizing FFA from acetate. Key words: Sheep, growth, fat-tail, FFA, acetate, turnover

scholarly journals Plasma free fatty acid concentration is closely tied to whole body peak fat oxidation rate during repeated exercise

2019 ◽  
Vol 126 (6) ◽  
pp. 1563-1571 ◽  
Author(s):  
Jacob Frandsen ◽  
Stine Dahl Vest ◽  
Christian Ritz ◽  
Steen Larsen ◽  
Flemming Dela ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Free Fatty Acid ◽  
Body Fat ◽  
Oxidation Rate ◽  
Plasma Free Fatty Acid ◽  
Fat Oxidation ◽  
Whole Body ◽  
Exercise Tests ◽  
Repeated Exercise ◽  
Plasma Ffa

Plasma free fatty acids (FFA) are a major contributor to whole body fat oxidation during exercise. However, the extent to which manipulating plasma FFA concentrations will influence whole body peak fat oxidation rate (PFO) during exercise remains elusive. In this study we aimed to increase plasma FFA concentrations through a combination of fasting and repeated exercise bouts. We hypothesized that an increase in plasma FFA concentration would increase PFO in a dose-dependent manner. Ten healthy young (31 ± 6 yr) (mean ± SD) well-trained (maximal oxygen uptake 65.9 ± 6.1 ml·min−1·kg−1) men performed four graded exercise tests (GXTs) on 1 day. The GXTs were interspersed by 4 h of bed rest. This was conducted either in a fasted state or with the consumption of a standardized carbohydrate-rich meal 3.5 h before each GXT. Fasting and previous GXTs resulted in a gradual increase in PFO from 0.63 ± 0.18 g/min after an overnight fast (10 h) to 0.93 ± 0.17 g/min after ∼22 h of fasting and three previous GXTs. This increase in PFO coincided with an increase in plasma FFA concentrations ( r2 = 0.73, P < 0.0001). Ingestion of a carbohydrate-rich meal 3.5 h before each GXT resulted in unaltered PFO. This was also reflected in unchanged plasma FFA, glucose, and insulin concentrations. In this study we show that plasma FFA availability is closely tied to whole body PFO and that the length of fasting combined with previous exercise are robust stimuli toward increasing plasma FFA concentration, highlighting the importance for preexercise standardization when conducting GXTs measuring substrate oxidation. NEW & NOTEWORTHY We show that peak fat oxidation is increased in close relationship with plasma free fatty acid availability after combined fasting and repeated incremental exercise tests in healthy highly trained men. Therefore it may be argued that whole body fat oxidation rate measured in most cases after an overnight fast indeed does not represent whole body maximal fat oxidation rate but a whole body peak fat oxidation rate within the context of the preexercise standardization obtained in the study design.

scholarly journals An evaluation of the IDEEA™ activity monitor for estimating energy expenditure

2012 ◽  
Vol 109 (1) ◽  
pp. 173-183 ◽  
Author(s):  
Stephen Whybrow ◽  
Patrick Ritz ◽  
Graham W. Horgan ◽  
R. James Stubbs
Keyword(s):  
Energy Balance ◽  
Energy Expenditure ◽  
Indirect Calorimetry ◽  
Activity Patterns ◽  
Activity Monitor ◽  
Whole Body ◽  
Similar Estimate ◽  
Free Living ◽  
Doubly Labelled Water ◽  
D 12

Objective estimates of activity patterns and energy expenditure (EE) are important for the measurement of energy balance. The Intelligent Device for Energy Expenditure and Activity (IDEEA) can estimate EE from the thirty-five postures and activities it can identify and record. The present study evaluated the IDEEA system's estimation of EE using whole-body indirect calorimetry over 24 h, and in free-living subjects using doubly-labelled water (DLW) over 14 d. EE was calculated from the IDEEA data using calibration values for RMR and EE while sitting and standing, both as estimated by the IDEEA system (IDEEAest) and measured by indirect calorimetry (IDEEAmeas). Subjects were seven females and seven males, mean age 38·1 and 39·7 years, mean BMI 25·2 and 26·2 kg/m2, respectively. The IDEEAest method produced a similar estimate of EE to the calorimeter (10·8 and 10·8 MJ, NS), while the IDEEAmeas method underestimated EE (9·9 MJ, P < 0·001). After removing data from static cycling, which the IDEEA was unable to identify as an activity, both the IDEEAest and IDEEAmeas methods overestimated EE compared to the calorimeter (9·9 MJ, P < 0·001; 9·1 MJ, P < 0·05 and 8·6 MJ, respectively). Similarly, the IDEEA system overestimated EE compared to DLW over 14 d; 12·7 MJ/d (P < 0·01), 11·5 MJ/d (P < 0·01) and 9·5 MJ/d for the IDEEAest, IDEEAmeas and DLW, respectively. The IDEEA system overestimated EE both in the controlled laboratory and free-living environments. Using measured EE values for RMR, sitting and standing reduced, but did not eliminate, the error in estimated EE.

scholarly journals Peak Fat Oxidation Rate Is Closely Associated With Plasma Free Fatty Acid Concentrations in Women; Similar to Men

2021 ◽  
Vol 12 ◽  
Author(s):  
Jacob Frandsen ◽  
Axel Illeris Poggi ◽  
Christian Ritz ◽  
Steen Larsen ◽  
Flemming Dela ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Free Fatty Acid ◽  
Plasma Free Fatty Acid ◽  
Fat Oxidation ◽  
Whole Body ◽  
Men And Women ◽  
Fed State ◽  
Repeated Exercise ◽  
Graded Exercise ◽  
Plasma Ffa

Introduction: In men, whole body peak fat oxidation (PFO) determined by a graded exercise test is closely tied to plasma free fatty acid (FFA) availability. Men and women exhibit divergent metabolic responses to fasting and exercise, and it remains unknown how the combined fasting and exercise affect substrate utilization in women. We aimed to investigate this, hypothesizing that increased plasma FFA concentrations in women caused by fasting and repeated exercise will increase PFO during exercise. Then, that PFO would be higher in women compared with men (data from a previous study).Methods: On two separate days, 11 young endurance-trained women were investigated, either after an overnight fast (Fast) or 3.5 h after a standardized meal (Fed). On each day, a validated graded exercise protocol (GXT), used to establish PFO by indirect calorimetry, was performed four times separated by 3.5 h of bed rest both in the fasted (Fast) or fed (Fed) state.Results: Peak fat oxidation increased in the fasted state from 11 ± 3 (after an overnight fast, Fast 1) to 16 ± 3 (mean ± SD) mg/min/kg lean body mass (LBM) (after ~22 h fast, Fast 4), and this was highly associated with plasma FFA concentrations, which increased from 404 ± 203 (Fast 1) to 865 ± 210 μmol/L (Fast 4). No increase in PFO was found during the fed condition with repeated exercise. Compared with trained men from a former identical study, we found no sex differences in relative PFO (mg/min/kg LBM) between men and women, in spite of significant differences in plasma FFA concentrations during exercise after fasting.Conclusion: Peak fat oxidation increased with fasting and repeated exercise in trained women, but the relative PFO was similar in young trained men and women, despite major differences in plasma lipid concentrations during graded exercise.

Regional glycerol and free fatty acid metabolism before and after meal ingestion

1999 ◽  
Vol 276 (5) ◽  
pp. E863-E869 ◽  
Author(s):  
Michael D. Jensen
Keyword(s):  
Fatty Acid ◽  
Free Fatty Acid ◽  
Peripheral Circulation ◽  
Whole Body ◽  
Glycerol Release ◽  
Production Rates ◽  
Before And After ◽  
Release Ratio ◽  
Glycerol Uptake ◽  
Meal Ingestion

We measured splanchnic and leg glycerol [and free fatty acid (FFA)] uptake and release in 11 healthy volunteers before and after meal ingestion to assess whether regional FFA-to-glycerol release ratios mirror systemic release ratios. Basal splanchnic triglyceride release was also assessed. Although basal splanchnic glycerol uptake (111 ± 18 μmol/min) accounted for most of systemic glycerol rate of appearance (156 ± 20 μmol/min), leg glycerol uptake was also noted. The basal, systemic FFA-to-glycerol release ratio was less (2.6 ± 0.2, P < 0.05) than the splanchnic ratio of 6.1 ± 1.3, and the leg FFA-to-glycerol release ratio under fed conditions was less than the systemic ratio (0.9 ± 0.1 vs. 1.6 ± 0.2, respectively, P< 0.05). Basal splanchnic triglyceride production rates were 74 ± 20 μmol/min, which could produce equimolar amounts of glycerol in the peripheral circulation via lipoprotein lipase action. In summary, 1) regional FFA-to-glycerol release ratios do not mirror systemic ratios, 2) leg glycerol uptake occurs in humans, and 3) splanchnic triglyceride production rates are substantial relative to systemic glycerol appearance. Glycerol appearance rates may not be a quantitative index of whole body lipolysis.

Free fatty acid-induced peripheral insulin resistance augments splanchnic glucose uptake in healthy humans

2002 ◽  
Vol 283 (2) ◽  
pp. E346-E352 ◽  
Author(s):  
Mandeep Bajaj ◽  
Rachele Berria ◽  
Thongchai Pratipanawatr ◽  
Sangeeta Kashyap ◽  
Wilailak Pratipanawatr ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Free Fatty Acid ◽  
Glucose Uptake ◽  
Healthy Subjects ◽  
Whole Body ◽  
Oral Glucose ◽  
Glucose Load ◽  
Healthy Humans ◽  
Insulin Clamp ◽  
Glucose Ingestion

To investigate the effect of elevated plasma free fatty acid (FFA) concentrations on splanchnic glucose uptake (SGU), we measured SGU in nine healthy subjects (age, 44 ± 4 yr; body mass index, 27.4 ± 1.2 kg/m2; fasting plasma glucose, 5.2 ± 0.1 mmol/l) during an Intralipid-heparin (LIP) infusion and during a saline (Sal) infusion. SGU was estimated by the oral glucose load (OGL)-insulin clamp method: subjects received a 7-h euglycemic insulin (100 mU · m−2 · min−1) clamp, and a 75-g OGL was ingested 3 h after the insulin clamp was started. After glucose ingestion, the steady-state glucose infusion rate (GIR) during the insulin clamp was decreased to maintain euglycemia. SGU was calculated by subtracting the integrated decrease in GIR during the period after glucose ingestion from the ingested glucose load. [3-3H]glucose was infused during the initial 3 h of the insulin clamp to determine rates of endogenous glucose production (EGP) and glucose disappearance (Rd). During the 3-h euglycemic insulin clamp before glucose ingestion, Rd was decreased (8.8 ± 0.5 vs. 7.6 ± 0.5 mg · kg−1 · min−1, P < 0.01), and suppression of EGP was impaired (0.2 ± 0.04 vs. 0.07 ± 0.03 mg · kg−1 · min−1, P < 0.01). During the 4-h period after glucose ingestion, SGU was significantly increased during the LIP vs. Sal infusion study (30 ± 2 vs. 20 ± 2%, P < 0.005). In conclusion, an elevation in plasma FFA concentration impairs whole body glucose Rd and insulin-mediated suppression of EGP in healthy subjects but augments SGU.

INTERRELATIONSHIPS BETWEEN BLOOD METABOLITES AND AN EVALUATION OF THEIR USE AS CRITERIA OF ENERGY STATUS OF COWS IN EARLY LACTATION

1974 ◽  
Vol 54 (3) ◽  
pp. 293-303 ◽  
Author(s):  
J. D. ERFLE ◽  
L. J. FISHER ◽  
F. D. SAUER
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Free Fatty Acid ◽  
Energy Balance ◽  
Free Fatty Acids ◽  
Blood Metabolites ◽  
Control Group ◽  
Early Lactation ◽  
Energy Status ◽  
Treatment Groups

Correlation and regression coefficients were calculated for blood metabolites, milk components, energy balance and efficiency of energy utilization for a total of 120 cows. The animals were on propylene glycol and glycerol feeding experiments, and correlation coefficients were calculated for combinations of parameters with the objective of assessing the effect of additive and level of additive on the constancy of these relationships. In order to attempt an explanation of the variation in relationships between treatment groups, two groups each comprising 19 animals were chosen, based on blood ketone body levels. These groups provided a comparison between stressed (ketotic) and non-stressed (control) animals. Blood glucose was more highly correlated with acetoacetate and β-hydroxybutyrate than with free fatty acids when calculated for treatment groups. When calculated for the two selected groups, significant correlations (P < 0.01) for glucose vs. acetoacetate, β-hydroxybutyrate and free fatty acids were −0.56, −0.61 and −0.28, respectively, for the ketotic group. No significant correlations (P > 0.05) were found between these parameters in the control group. The correlations between blood glucose, acetoacetate and β-hydroxybutyrate and energy balance were very low. Plasma-free fatty acid levels were more closely associated with energy balance than were the other blood metabolites. When energy balance and free fatty acid correlations were compared for ketotic and control groups, only the control group showed a significant (P < 0.01) coefficient (r = − 0.42). The correlation between mean plasma-free fatty acids and mean body weight change over the experimental period for all animals, with time and treatment effects removed, was significant (r = − 0.54, P < 0.01). The estimated free fatty acid level at zero body weight change was 0.53 μ eq per ml plasma. It is concluded that although free fatty acid levels are more sensitive than glucose as an indicator of energy status of the lactating cow, the excessive variability of this relationship during early lactation drastically limits its usefulness.

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