• Associations between Selected Dietary Factors, Selected Obesity-Related Metabolic Markers (Leptin, C-peptide, and High-sensitivity C-reactive Protein), and Lung Cancer: A Matched Case-Control Study Nested in the Prospective PLCO Trial

      Chen, Yixian; Applied Health Sciences Program
      The purpose of the study was to evaluate the associations between selected dietary factors, body mass index (BMI), selected obesity-related metabolic markers, and lung cancer risk as well as histological types in ever-smokers (former and current-smokers). Characteristics of interest included BMI at age 50, fruits and vegetables daily frequency, supplemental beta-carotene intake, C-peptide (CP), high-sensitivity C-reactive protein (hsCRP), and leptin concentrations. Data from the Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial were analyzed. Linear regression models were used to describe the associations between quantitative variables. The relationships between variables of interest and lung cancer were studied by logistic regression modelling. Multivariable fractional polynomial (MFP) models were utilized to address non-linearity in these associations. Higher fruits and vegetables daily frequency and supplemental beta-carotene intake were associated with a lower risk of lung cancer in ever-smokers. Metabolic markers, C-peptide and hsCRP, were positively associated with lung cancer risk. Inverse relationships were observed between BMI and leptin with lung cancer risk. The relationships between selected dietary factors, BMI, selected metabolic markers, and lung cancer risk were more prominent in non-small cell lung cancer (NSCLC) in comparison with those in small cell lung cancer (SCLC).
    • Do weight status and weight perception predict academic acheivement in adolescents? A longitudinal analysis of the COMPASS study.

      Livermore, Maram; Applied Health Sciences Program
      Abstract Background: Recent evidence suggests perceptions of overweight account for the psychosocial consequences typically associated with obesity. Previous research indicates the presence of an obesity achievement gap, yet limited research has explored weight perception in association with academic achievement. Previous studies have focused on grades and degree attainment, without consideration of student aspirations and perceived support and ability to achieve higher levels of education. This thesis examined how Body Mass Index (BMI) classification and weight perception relate to academic performance and postsecondary aspirations and expectations in a large cohort of Canadian adolescents. Additionally, the interaction between BMI status and perceptions of weight was examined in relation to academic achievement outcomes. Methods: Two-year survey data from 25,673 grade 9-12 students attending the 122 Canadian schools that participated in Year 6 (2017/2018) and Year 7 (2018/2019) of the COMPASS study were used. Generalized estimating equation models were used to examine associations between students’ BMI classification and weight perception and their math and English/French course grades and post-secondary academic aspirations and expectations. All models were stratified by gender and adjusted for sociodemographic variables and school clustering. Results: Boys and girls with BMI of obesity and missing BMI classification reported lower grades and post-secondary aspirations and expectations when compared to those with Normal BMI. Similarly, boys and girls with overweight BMI reported lower math and language grades than those with Normal-weight BMIs. Relative to their peers with normal-weight BMI and “about right” perceptions, those with overweight perceptions and BMI of overweight/obesity reported lower academic grades and post-secondary aspirations and expectations. There was evidence of an additive effect for girls and boys with overweight perceptions and BMI of overweight/obesity on academic outcomes. About right perceptions of weight were protective against lower math grades for boys and girls with overweight/obesity BMI. Results varied by gender and across academic outcomes. Conclusions: Overall, this thesis demonstrates that an obesity achievement gap remains when controlling for students’ perceptions of their weight. Perceptions of overweight had a detrimental effect on academic performance and aspirations/expectations for students with BMI classifications of overweight and obesity, as well as grade outcomes for those with BMI of normal-weight. Results suggest that barriers to academic success exist for students with larger bodies. Future studies should explore the role of internalized and externalized weight bias.
    • The effects of a high fat diet on musculoskeletal health in aged male C57BL/6J mice

      Bott, Kirsten; Applied Health Sciences Program
      Aging and obesity are two major aspects that can negatively impact musculoskeletal structure and function. It is important to study these aspects because of current high rates of obesity and the increasing proportion of seniors in North America. This study investigated the effects of a long-term high fat and sucrose diet (HFS) superimposed with aging on bone and muscle structure and function. Male C57BL/6J mice were randomized 1 of 2 diets: control (AGE, AIN93M, 10.3% kcal fat, 100 g/kg sucrose) or HFS (HFS-AGE, 45.3% kcal fat 200 g/kg sucrose) for 13 weeks starting at 20 weeks of age to represent middle age. Trabecular bone structure and volumetric bone mineral density (vBMD), body composition, and grip strength were measured longitudinally at 20, 24, 28, and 32 weeks of age. In vitro contractile measures were performed on isolated soleus and extensor digitorum longus (EDL) muscles at baseline (BSL, 20 weeks of age, n=11) and at the end of the 13-week intervention when AGE (n=12) and HFS-AGE (n=12) mice were 33 weeks of age. Both the AGE and HFS-AGE groups had similar declines in trabecular bone (bone structure and vBMD). For muscle contractile function, HFS+AGE resulted in increased soleus cross-sectional area (CSA) compared AGE (p=0.0008), but this did not translate to greater twitch or tetanus peak force. The ratio of outcomes of bone to muscle declined in both the AGE and HFS-AGE groups as a result of a greater decline in key measures of bone structure (BV/TV) than muscle function (soleus and EDL peak tetanus and CSA) and was not altered by feeding HFS. In conclusion, beginning a HFS diet during middle age did not exacerbate age-related declines in bone or muscle, but these tissues do not decline in a coordinate manner with aging as bone structure declined at a greater rate than muscle function.
    • Influence of timing of milk consumption coupled with endurance training on body composition and endurance training adaptations in humans.

      Euiler, Elizabeth; Applied Health Sciences Program (Brock University, 2014-03-24)
      Consumption of low-fat milk (LFM) after resistance training has been shown to have positive influences on body composition and training adaptations; however, little research has examined the effects of LFM consumption following endurance training. The purpose of the study was to look at the effects of combining additional servings of LFM following endurance exercise on body composition, bone health, and training adaptations. 40 healthy males were recruited. Individuals were randomized into 4 groups – DEI (750mL LFM immediately post exercise), DEA (750mL LFM 4 hrs prior to or 6 hrs post exercise), CEI (750mL carbohydrate beverage immediately post-exercise), and CEA (750mL carbohydrate beverage immediately post-exercise). Participants took part in a 12-week endurance training intervention (1 h/day, 3 d/wk, ~60% max HR). 22 participants completed the study. Analysis showed significant increases in lean mass, spinal bone mineral content, relative VO2peak, and a decrease in Trap 5β across all groups (p < 0.05).