Health, Exercise, and Sports Sciences ETDs

Roger Vaughan

Publication Date

7-12-2014

Abstract

Background: Commercially available dietary products advertised to promote weight loss are an under researched but heavily purchased commodity in the United States. Despite only limited evidence, interest in dietary supplements continues to increase. Obesity is an increasingly prevalent and preventable morbidity with multiple behavioral, surgical and pharmacological interventions currently available. Commercially available dietary supplements are often advertised to stimulate metabolism and cause rapid weight and/or fat loss, although few well controlled studies have demonstrated such effects. This work uniquely summarizes the current evidence evaluating the efficacy of several over-the-counter thermogenic products for their effects on resting energy expenditure. Additionally, this work outlines the important therapeutic benefits provided by dietary stimulators of metabolism and peroxisome proliferator-activated receptor gamma co-activator 1 (PGC-1) in skeletal muscle. Our work uniquely describes the effects of a commercially available dietary supplement on resting metabolic rate in humans as well as the metabolic and biochemical effects in vitro. Methods: Human rhabdomyosarcoma cells (RD) and mouse myoblasts (C2C12) were cultured under standard conditions and treated with various doses of a commercially available supplement (RF) for various durations and assessed for changes in metabolism, metabolic gene expression and mitochondrial content. Additionally, human subjects ingested either placebo or RF in a double-blind placebo controlled fashion and metabolic rate and blood pressure were measured at 3 time points for 3 hours post-ingestion. Results: RF enhanced metabolism, metabolic gene expression, and mitochondrial content in both cell models. RF also enhanced energy expenditure in human male subjects without altering substrate utilization. RF also significantly increased systolic blood pressure. Conclusion: RF appears to increase metabolism immediately following ingestion, although additional research is needed to assess safety and efficacy for human weight loss.

Keywords

Thermogenic Supplements, Fat Burners, Metabolic Rate, Obesity, Caffeine, Phytochemicals, 5' adenosine monophosphate-activated protein kinase (AMPK), Peroxisome proliferator-activated receptor gamma co-activator 1 (PGC-1), Mitochondrial Biogenesis

Document Type

Dissertation

Language

English

Degree Name

Physical Education, Sports and Exercise Science

Level of Degree

Doctoral

Department Name

Health, Exercise, and Sports Sciences

First Committee Member (Chair)

Conn, Carole

Second Committee Member

Kravitz, Len

Third Committee Member

Bisoffi, Marco

Fourth Committee Member

Trujillo, Kristina

Fifth Committee Member

Mermier, Christine

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