Dissertation Defence: Embracing the Complexity of Diet in Type 2 Diabetes Prevention

Azize Nur Yildirim, supervised by Drs. Mary Jung and Sarah Purcell, will defend their dissertation titled “Embracing the Complexity of Diet in Type 2 Diabetes Prevention: Appetitive Traits, Food Groups, Energy and Nutrient Intake” in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Kinesiology.

An abstract for Azize Nur Yildirim’s dissertation is included below.

Examinations are open to all members of the campus community as well as the general public. Registration is not required for in-person exams.

Abstract

Eating behaviours and dietary intake are modifiable determinants of type 2 diabetes (T2D) risk, yet key gaps remain in understanding (i) how appetitive traits relate to metabolic outcomes in individuals with prediabetes and (ii) how dietary intake changes and relates to metabolic outcomes following brief, community-based diabetes prevention programs (DPPs). This dissertation addressed these gaps using three complementary studies examining appetitive traits and dietary intake in relation to metabolic outcomes within Small Steps for Big Changes (SSBC), a brief, community-based DPP targeting dietary and exercise behaviour change.

In a cross-sectional analysis of 115 SSBC participants, Food Responsiveness was positively correlated with body mass index (BMI) (rs = 0.414, p < 0.001) and waist circumference (WC) (rs = 0.459, p < 0.001) in females. In males, Emotional Overeating was positively correlated with hemoglobin A1c (HbA1c) (rs = 0.449, p = 0.003), whereas Slowness in Eating was negatively correlated with HbA1c (rs = −0.325, p = 0.038). In a retrospective longitudinal analysis of 326 participants, major food group intakes improved from baseline to 12 months after SSBC (p < 0.050) except for vegetables. Vegetable, fruit, sweets, and bread intake were associated with body weight (p = 0.013, 0.018, 0.002, and <0.001, respectively), and fruit and bread intake were associated with WC (p = 0.002 and <0.001). Diet-by-time interactions were observed for vegetable and red meat intake in relation to body weight (p = 0.032 and 0.045). Building on these findings, a prospective longitudinal analysis of 115 participants showed significant reductions in energy and carbohydrate intake over six months after SSBC, alongside improvements in metabolic outcomes (p < 0.050). Greater fibre intake was associated with lower body weight (β = −0.109 ± 0.050, p = 0.030) and showed trends toward lower BMI (β = −0.034 ± 0.017, p = 0.050) and HbA1c (β = −0.007 ± 0.004, p = 0.084). Greater total carbohydrate intake was also associated with reductions in body weight (β = −0.019 ± 0.007, p = 0.012) and BMI (β = −0.006 ± 0.003, p = 0.012), whereas changes in energy intake were not associated with metabolic outcomes (p > 0.050).

Collectively, appetitive traits and dietary intake relate to key metabolic outcomes relevant to T2D risk, and that participation in a brief, community-based DPP can support sustained dietary changes at both the food-group and energy and nutrient levels that contribute to metabolic improvements. Future research should integrate appetitive traits within DPPs, continue refining dietary assessment methods to better elucidate diet–metabolic health relationships, and examine complementary mechanisms beyond dietary intake that may contribute to metabolic improvements within community-based DPPs.