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Associations Between Weight Loss and Regain, Cytokine Concentration, and Insulin Resistance Among Overweight/Obese Adults

Ambeba, Erica Joy (2013) Associations Between Weight Loss and Regain, Cytokine Concentration, and Insulin Resistance Among Overweight/Obese Adults. Doctoral Dissertation, University of Pittsburgh. (Unpublished)

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Abstract

Obesity is a problem of great public health significance, with over one-third of individuals in the U.S. being obese; it is also associated with an increased risk for cardiometabolic diseases. Abnormal cytokine secretion of pro-inflammatory (IL-6 and TNF-α) and anti-inflammatory (adiponectin and IL-10) cytokines is a hallmark of obesity, linking it to the development of insulin resistance (IR). Weight maintenance after intentional weight loss is difficult to achieve, and individuals often regain weight, entering into a pattern of weight cycling. Little is known on the associations between weight cycling, cytokines, and IR. This dissertation, comprising three research papers, aimed to examine these associations among non-diabetic, overweight/obese adults (N=66) enrolled in the Self-Monitoring And Recording using Technology (SMART) Trial, a 24-month clinical trial of behavioral weight loss treatment.
The first paper examined patterns of weight loss and regain and its effect on pro- and anti-inflammatory cytokines from baseline to 24 months. An interaction between gender and percent change in weight on percent change in adiponectin over time was detected [b(se)=0.9(0.2), p=.0003]. There was an association with increases in IL-6 [b(se)=0.9(0.3), p=.001]. The second paper examined patterns of weight loss and regain and their effect on metabolic measures from baseline to 24 months. Weight change was positively associated with changes in insulin [b(se)=0.5(0.1), p≤.0001] and HOMA-IR [b(se)=0.8(0.2), p≤.0001] over time. The third paper examined polymorphisms in genes encoding IL-6, TNF-α, adiponectin, and IL-10 and their association with cytokine concentration and IR. C allele carriers in IL-10 polymorphism rs1800896 had higher HOMA-IR compared to TT carriers [b(se)=1.0(0.4), p=0.02]. Variant allele carriers in IL-10 polymorphisms rs1800871 and rs1800872 had lower HOMA-IR compared to individuals homozygous for the wild type allele [for both polymorphisms: b(se)=-1.2(0.4), p=.01]. There was a significant within-group decrease in HOMA-IR from baseline to 24 months among individuals with the rs1800872 GG genotype but not for T allele carriers.
These findings reveal weight loss to be an important tool in reducing inflammation and improving insulin sensitivity; however, weight regain can attenuate these improvements. Moreover, the association between IL-10 polymorphisms and IR suggests that cytokine genes play a role in metabolic outcomes.


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Details

Item Type: University of Pittsburgh ETD
Status: Unpublished
Creators/Authors:
CreatorsEmailPitt UsernameORCID
Ambeba, Erica Joyejc25@pitt.eduEJC25
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairBurke, Lora Elbu100@pitt.eduLBU100
Committee MemberBrooks, Maria M brooks@edc.pitt.eduMBROOKS
Committee MemberEvans, Rhobert WEvansR@edc.pitt.edu RWE2
Committee MemberStyn, Mindi Amimst31@pitt.eduMIMST31
Date: 27 June 2013
Date Type: Publication
Defense Date: 12 April 2013
Approval Date: 27 June 2013
Submission Date: 3 April 2013
Access Restriction: 1 year -- Restrict access to University of Pittsburgh for a period of 1 year.
Number of Pages: 137
Institution: University of Pittsburgh
Schools and Programs: Graduate School of Public Health > Epidemiology
Degree: PhD - Doctor of Philosophy
Thesis Type: Doctoral Dissertation
Refereed: Yes
Uncontrolled Keywords: Obesity, weight loss, cytokines, insulin resistance
Date Deposited: 27 Jun 2013 18:05
Last Modified: 15 Nov 2016 14:11
URI: http://d-scholarship.pitt.edu/id/eprint/18172

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