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Hames, Kazanna Calais (2011) FAT METABOLISM IN SEVERELY OBESE ADULTS. Doctoral Dissertation, University of Pittsburgh. (Unpublished)

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Key metabolic impairments in obesity are reduced skeletal muscle and systemic fatty acid oxidation (FAO). Few clinical trials in severely obese adults examined how the BMI classification relates to FAO and how the addition of exercise to weight loss interventions impacts FAO. PURPOSE: To examine how BMI levels that include severely obese relate to FAO. To examine how weight loss interventions with or without exercise in severely obese adults impact FAO. METHODS: Adults (BMI:20-52 kg/m2) were recruited to examine skeletal muscle FAO with histochemical analysis of muscle biopsies and systemic FAO at rest and during submaximal exercise with indirect calorimetry. Changes in skeletal muscle and systemic FAO of severely obese adults randomized to one of the following weight loss interventions were examined: surgery (S), surgery plus exercise (SE) and diet plus exercise (DE). RESULTS: BMI was not significantly related to skeletal muscle or systemic FAO at rest. During exercise at an absolute workload, BMI only had a significant moderate, positive association with systemic absolute FAO (mg/min) in the univariate analysis (r=0.46,p<0.01). During exercise at the relative workload, BMI had a moderate, negative association with respiratory exchange ratio (RER; r=0.54,p<0.01) and moderate, positive associations with absolute FAO (r=0.45,p<0.01) and proportion of energy derived from fat (EF; r=0.55,p<0.01). When controlling for confounders (age, gender, race, cardiovascular fitness and physical activity), BMI only maintained significance with RER, explaining 21% of the variance (p<0.01). Upon completion of weight loss interventions, change in skeletal muscle or systemic FAO at rest was not significantly different across intervention groups. DE had greater positive changes in RER and EF during submaximal exercise bouts compared to the other groups (p<0.05). SE had significantly greater positive changes compared to S only with FAO normalized to fat free mass during the relative submaximal workload (p<0.01). CONCLUSIONS: BMI does not explain the variance in FAO at rest, but is associated with higher FAO during submaximal exercise bouts. Inclusion of exercise to weight loss induced by caloric restriction results in more favorable changes in FAO during sumbaximal exercise compared to surgery induced weight loss with or without exercise.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Hames, Kazanna Calaiskch15@pitt.eduKCH15
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairGoodpaster, Bretbgood@pitt.eduBGOOD
Committee CoChairJakicic, Johnjjakicic@pitt.eduJJAKICIC
Committee MemberNagle, Elizabethnagle@pitt.eduNAGLE
Committee MemberKing, Wendykingw@edc.pitt.eduWCK1
Date: 6 January 2011
Date Type: Completion
Defense Date: 29 November 2010
Approval Date: 6 January 2011
Submission Date: 10 December 2010
Access Restriction: 5 year -- Restrict access to University of Pittsburgh for a period of 5 years.
Institution: University of Pittsburgh
Schools and Programs: School of Education > Health, Physical, Recreational Education
Degree: PhD - Doctor of Philosophy
Thesis Type: Doctoral Dissertation
Refereed: Yes
Uncontrolled Keywords: fat oxidation; severe obesity; physical activity; weight loss intervention
Other ID:, etd-12102010-084858
Date Deposited: 10 Nov 2011 20:10
Last Modified: 15 Nov 2016 13:54


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