Effects of p-Synephrine during Exercise: A Brief Narrative Review

The p-synephrine is the principal phytochemical found in bitter orange (Citrus aurantium). This substance is widely included in dietary supplements for weight loss/body fat reduction due to its potential benefits of increasing fat oxidation. For years, p-synephrine-containing dietary supplements have been marketed without proper knowledge of their true effectiveness to enhance fat utilization, especially when combined with exercise. However, the effects of p-synephrine on fat oxidation during exercise have been investigated in the last few years. The aim of the current discussion is to summarize the evidence on the effects of p-synephrine intake on fat oxidation and performance during exercise. Previous investigations have demonstrated that the acute intake of p-synephrine does not modify running sprint performance, jumping capacity, or aerobic capacity. However, the acute intake of p-synephrine, in a dose of 2–3 mg/kg of body mass, has been effective to enhance the rate of fat oxidation during incremental and continuous exercise. This effect has been observed in a range of exercise workloads between 30% and 80% of peak oxygen uptake (VO2peak). The p-synephrine has the ability to increase the maximal rate of fat oxidation during exercise of increasing intensity without affecting the workload at which maximal fat oxidation is obtained (Fatmax). The effect of p-synephrine on fat oxidation is normally accompanied by a concomitant reduction of carbohydrate utilization during exercise, without modifying the energy expended during exercise. The shifting in substrate oxidation is obtained without any effect on heart rate during exercise and the prevalence of adverse effects is negligible. Thus, the acute use of p-synephrine, or p-synephrine-containing products, might offer some benefits for those individuals seeking higher fat utilization during exercise at low to moderate intensities. However, more research is still necessary to determine if the effect of p-synephrine on fat oxidation during exercise is maintained with chronic ingestion, in order to ascertain the utility of this substance in conjunction with exercise programs to produce an effective body fat/weight loss reduction.

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Fat Utilization in Healthy Subjects Consuming Diacylglycerol Oil Diet: Dietary and Whole Body Fat Oxidation

Lipids ◽

10.1007/s11745-008-3177-2 ◽

2008 ◽

Vol 43 (6) ◽

pp. 517-524 ◽

Cited By ~ 12

Author(s):

Masanobu Hibi ◽

Hideto Takase ◽

Koichi Yasunaga ◽

Tohru Yamaguchi ◽

Ushio Harada ◽

...

Keyword(s):

Body Fat ◽

Healthy Subjects ◽

Fat Oxidation ◽

Whole Body ◽

Fat Utilization ◽

Diacylglycerol Oil

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Aerobic fitness determines whole-body fat oxidation rate during exercise in the heat

Applied Physiology Nutrition and Metabolism ◽

10.1139/h10-068 ◽

2010 ◽

Vol 35 (6) ◽

pp. 741-748 ◽

Cited By ~ 2

Author(s):

Juan Del Coso ◽

Nassim Hamouti ◽

Juan Fernando Ortega ◽

Ricardo Mora-Rodriguez

Keyword(s):

Oxygen Uptake ◽

Body Fat ◽

Healthy Subjects ◽

Fat Oxidation ◽

Exercise Duration ◽

Substrate Oxidation ◽

Peak Oxygen Uptake ◽

Total Energy Expenditure ◽

Whole Body ◽

Blood Samples

The purpose of this study was to determine whole-body fat oxidation in endurance-trained (TR) and untrained (UNTR) subjects exercising at different intensities in the heat. On 3 occasions, 10 TR cyclists and 10 UNTR healthy subjects (peak oxygen uptake = 60 ± 6 vs. 44 ± 3 mL·kg–1·min–1; p < 0.05) exercised at 40%, 60%, and 80% peak oxygen uptake in a hot, dry environment (36 °C; 25% relative humidity). To complete the same amount of work in all 3 trials, exercise duration varied (107 ± 4, 63 ± 1, and 45 ± 0 min for 40%, 60%, and 80% peak oxygen uptake, respectively). Substrate oxidation was calculated using indirect calorimetry. Blood samples were collected at the end of exercise to determine plasma epinephrine ([EPI]plasma) and norepinephrine ([NEPI]plasma) concentrations. The maximal rate of fat oxidation was achieved at 60% peak oxygen uptake for the TR group (0.41 ± 0.01 g·min–1) and at 40% peak oxygen uptake for the UNTR group (0.28 ± 0.01 g·min–1). TR subjects oxidized absolutely (g·min–1) and relatively (% of total energy expenditure) more fat than UNTR subjects at 60% and 80% peak oxygen uptake (p < 0.05). At these exercise intensities, TR subjects also had higher [NEPI]plasma concentrations than UNTR subjects (p < 0.05). In the heat, whole-body peak fat oxidation occurs at higher relative exercise intensities in TR than in UNTR subjects (60% vs. 40% peak oxygen uptake). Moreover, TR subjects oxidize more fat than UNTR subjects when exercising at moderate to high intensities (>60% peak oxygen uptake).

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Leptin Replacement Prevents Weight Loss-Induced Metabolic Adaptation in Congenital Leptin-Deficient Patients

Endocrinology ◽

10.1210/endo.151.2.9998 ◽

2010 ◽

Vol 151 (2) ◽

pp. 839-840

Author(s):

Jose E. Galgani ◽

Frank L. Greenway ◽

Ma-Li Wong ◽

Julio Licinio ◽

Eric Ravussin

Keyword(s):

Weight Loss ◽

Energy Expenditure ◽

Body Fat ◽

Fat Oxidation ◽

Reference Population ◽

Fat Free Mass ◽

Low Calorie ◽

Low Calorie Diet ◽

Before And After ◽

Calorie Diet

ABSTRACT Context: Leptin regulates energy homeostasis by suppressing food intake; however, its role in energy expenditure and fat oxidation remains uncertain in humans. Objective: The aim of the study was to assess 24-h energy metabolism before and after weight loss induced by leptin treatment in congenital leptin-deficient subjects or low-calorie diet in controls. Design and Patients: We measured 24-h energy expenditure, 24-h fat oxidation, and body fat in three null homozygous leptin-deficient obese adults before and after weight loss induced by a 19-wk leptin replacement period (0.02-0.04 mg/kg/d). The same measures were performed in three obese controls pair-matched for sex, age, and weight loss induced by a 10- to 21-wk low-calorie diet. Measurements were preceded for 1 wk of weight stabilization. Energy expenditure was adjusted for fat-free mass, fat mass, sex, and age based on a reference population (n = 842; R2 = 0.85; P < 0.0001). Similarly, fat oxidation was adjusted for fat-free mass, percentage body fat, energy balance, and diet composition during the 24-h respiratory chamber stay (R2 = 0.38; P < 0.0001). Results: Before weight loss, congenital leptin-deficient and control subjects had similar energy expenditure. However, after weight loss (∼15 kg), controls had energy expenditures lower than expected for their new weight and body composition (−265 ± 76 kcal/d; P = 0.04), whereas leptin-treated subjects had values not different from the reference population (−128 ± 119 kcal/d; P = 0.67). Before weight loss, fat oxidation was similar between groups. However, after weight loss, leptin-treated subjects had higher fat oxidation than controls (P = 0.005) and higher than the reference population (P = 0.0001). Conclusion: In congenital leptin-deficient subjects, leptin replacement prevented the decrease in energy expenditure and fat oxidation often observed after weight loss.

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Effect of caloric restriction on body weight loss and body fat utilization in obese hyperglycemic mice (obob)

Metabolism ◽

10.1016/0026-0495(72)90015-7 ◽

1972 ◽

Vol 21 (1) ◽

pp. 10-17 ◽

Cited By ~ 15

Author(s):

C. Chlouverakis

Keyword(s):

Weight Loss ◽

Body Weight ◽

Caloric Restriction ◽

Body Fat ◽

Body Weight Loss ◽

Fat Utilization

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Leptin Replacement Prevents Weight Loss-Induced Metabolic Adaptation in Congenital Leptin-Deficient Patients

The Journal of Clinical Endocrinology & Metabolism ◽

10.1210/jc.2009-1739 ◽

2010 ◽

Vol 95 (2) ◽

pp. 851-855 ◽

Cited By ~ 42

Author(s):

Jose E. Galgani ◽

Frank L. Greenway ◽

Sinan Caglayan ◽

Ma-Li Wong ◽

Julio Licinio ◽

...

Keyword(s):

Weight Loss ◽

Energy Expenditure ◽

Body Fat ◽

Fat Oxidation ◽

Reference Population ◽

Fat Free Mass ◽

Low Calorie ◽

Low Calorie Diet ◽

Before And After ◽

Calorie Diet

Abstract Context: Leptin regulates energy homeostasis by suppressing food intake; however, its role in energy expenditure and fat oxidation remains uncertain in humans. Objective: The aim of the study was to assess 24-h energy metabolism before and after weight loss induced by leptin treatment in congenital leptin-deficient subjects or low-calorie diet in controls. Design and Patients: We measured 24-h energy expenditure, 24-h fat oxidation, and body fat in three null homozygous leptin-deficient obese adults before and after weight loss induced by a 19-wk leptin replacement period (0.02–0.04 mg/kg/d). The same measures were performed in three obese controls pair-matched for sex, age, and weight loss induced by a 10- to 21-wk low-calorie diet. Measurements were preceded for 1 wk of weight stabilization. Energy expenditure was adjusted for fat-free mass, fat mass, sex, and age based on a reference population (n = 842; R2 = 0.85; P < 0.0001). Similarly, fat oxidation was adjusted for fat-free mass, percentage body fat, energy balance, and diet composition during the 24-h respiratory chamber stay (R2 = 0.38; P < 0.0001). Results: Before weight loss, congenital leptin-deficient and control subjects had similar energy expenditure. However, after weight loss (∼15 kg), controls had energy expenditures lower than expected for their new weight and body composition (−265 ± 76 kcal/d; P = 0.04), whereas leptin-treated subjects had values not different from the reference population (−128 ± 119 kcal/d; P = 0.67). Before weight loss, fat oxidation was similar between groups. However, after weight loss, leptin-treated subjects had higher fat oxidation than controls (P = 0.005) and higher than the reference population (P = 0.0001). Conclusion: In congenital leptin-deficient subjects, leptin replacement prevented the decrease in energy expenditure and fat oxidation often observed after weight loss.

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Carbohydrate and fat oxidation in persons with lower limb amputation during walking with different speeds

Prosthetics and Orthotics International ◽

10.1177/0309364617740237 ◽

2017 ◽

Vol 42 (3) ◽

pp. 304-310

Author(s):

Terje Gjovaag ◽

Peyman Mirtaheri ◽

Inger Marie Starholm

Keyword(s):

Energy Expenditure ◽

Energy Cost ◽

Walking Speed ◽

Fat Oxidation ◽

Total Energy Expenditure ◽

Maximal Aerobic Capacity ◽

Carbohydrate Utilization ◽

Fat Utilization ◽

Transfemoral Amputees ◽

Energy Cost Of Walking

Background: Studies suggest that the energy expenditure of healthy persons (control) during walking with the preferred walking speed in steady-state conditions is dominated by fat oxidation. Conversely, carbohydrate and fat oxidation during walking is little investigated in transfemoral amputees. Objectives: To investigate carbohydrate and fat oxidation, energy cost of walking, and percent utilization of maximal aerobic capacity [Formula: see text]during walking. Study design: Eight transfemoral amputees and controls walked with their preferred walking speed and speeds 12.5% and 25% slower and faster than their preferred walking speed. Methods: Energy expenditure and fuel utilization were measured using a portable metabolic analyzer. Metabolic values are means ± standard deviation. Results: For transfemoral amputees (37.0 ± 10.9 years) and controls (39.0 ± 12.3 years), fat utilization at the preferred walking speed was 44.8% ± 7.2% and 45.0% ± 7.2% of the total energy expenditure, respectively. The preferred walking speed of the transfemoral amputees and controls was close to a metabolic cross-over speed, which is the speed where carbohydrate utilization increases steeply and fat utilization decreases. When walking fast, at 90 m min−1 (preferred walking speed plus 25%), transfemoral amputees utilized 70.7% ± 5.6% of their [Formula: see text], while the controls utilized 30.9% ± 4.5% ( p < 0.001) at the matching speed (control preferred walking speed). At 90 m min−1, carbohydrate utilization was 78% ± 4.7% and 55.2% ± 7.2% of the total energy expenditure for the transfemoral amputees and controls, respectively ( p < 0.01). Compared to the control, energy cost of walking was higher for the transfemoral amputees at all speeds (all comparisons; p < 0.001). Conclusion: At the preferred walking speed, carbohydrate, not fat, dominates energy expenditure of both transfemoral amputees and controls. For the transfemoral amputees, consequences of fast walking are very high [Formula: see text] utilization and rate of carbohydrate oxidation. Clinical relevance Research on the relationships between physical effort and fuel partitioning during ambulation could provide important insights for exercise-rehabilitation programs for lower limb amputees (LLA). Regular endurance exercise will improve maximal aerobic capacity and enable LLA to walk faster and at the same time expend less energy and improve fat utilization.

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Determinants of maximal whole-body fat oxidation in elite cross-country skiers: Role of skeletal muscle mitochondria

Scandinavian Journal of Medicine and Science in Sports ◽

10.1111/sms.13298 ◽

2018 ◽

Vol 28 (12) ◽

pp. 2494-2504 ◽

Cited By ~ 14

Author(s):

Sune Dandanell ◽

Anne-Kristine Meinild-Lundby ◽

Andreas B. Andersen ◽

Paul F. Lang ◽

Laura Oberholzer ◽

...

Keyword(s):

Skeletal Muscle ◽

Body Fat ◽

Fat Oxidation ◽

Whole Body ◽

Muscle Mitochondria ◽

Skeletal Muscle Mitochondria ◽

Cross Country

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Isoquinoline Alkaloids in Sows’ Diet Reduces Body Weight Loss during Lactation and Increases IgG in Colostrum

Animals ◽

10.3390/ani11082195 ◽

2021 ◽

Vol 11 (8) ◽

pp. 2195

Author(s):

Ester Arévalo Sureda ◽

Xuemei Zhao ◽

Valeria Artuso-Ponte ◽

Sophie-Charlotte Wall ◽

Bing Li ◽

...

Keyword(s):

Gene Expression ◽

Weight Loss ◽

Body Weight ◽

Body Weight Loss ◽

Muscle Thickness ◽

Passive Immunity ◽

Isoquinoline Alkaloids ◽

Back Muscle ◽

Fat Thickness ◽

And Performance

Isoquinoline alkaloids (IQ) exert beneficial antimicrobial and anti-inflammatory effects in livestock. Therefore, we hypothesized that supplementing sows’ diets with IQ during gestation would decrease farrowing stress, affecting the piglets’ development and performance. Sows were divided into: IQ1, supplemented with IQ from gestation day 80 (G80) to weaning; IQ2, supplemented from gestation day 110 (G110) to weaning, and a non-supplemented (NC) group. Sow body weight (BW), feed intake, back-fat thickness and back-muscle thickness were monitored. Cortisol, glucose and insulin were measured in sows’ blood collected 5 d before, during, and after 7 d farrowing. Protein, fat, IgA and IgG were analyzed in the colostrum and milk. Piglets were monitored for weight and diarrhea score, and for ileum histology and gene expression 5 d post-weaning. IQ-supplemented sows lost less BW during lactation. Glucose and insulin levels were lower in the IQ groups compared to NC-sows 5 d before farrowing and had higher levels of protein and IgG in their colostrum. No other differences were observed in sows, nor in the measured parameters in piglets. In conclusion, IQ supplementation affected sows’ metabolism, reducing body weight loss during lactation. Providing IQ to sows from their entrance into the maternity barn might be sufficient to induce these effects. IQ improved colostrum quality, increasing the protein and IgG content, improving passive immunity for piglets.

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