Advisory Committee Chair
Barbara Gower
Document Type
Thesis
Date of Award
2024
Degree Name by School
Master of Science (MS) School of Health Professions
Abstract
Some but not all studies show participants who have higher baseline insulin responses lose more weight on a low glycemic load compared to a high glycemic load diet. Most prior research tested the relationship between insulin and weight changes with only one insulin response variable, such as insulin from an orally or intravenously (IV) administered metabolic test. We tested whether insulin responses (IV or oral) predicted changes in body fat among participants undergoing diet-induced weight loss. This study was a secondary analysis of a clinical trial. In the parent study, participants were randomized to either a reduced carbohydrate (ReducedCHO) or a standard carbohydrate (StandardCHO) diet for 16 weeks. The diets were eucaloric for the first 8 weeks and hypocaloric for the following 8 weeks. The acute insulin response to glucose (AIRg) during an intravenous glucose tolerance test (IVGTT) and the insulin concentration at 30 minutes (insulin-30) during a liquid meal tolerance test (LMTT) were collected at baseline. Dual energy x-ray absorptiometry was used to measure total body fat at baseline and week-16. Multiple linear regression analyses were used to test whether the insulin variables predicted the 16-week change in body fat, after adjusting for diet, baseline BMI, and baseline insulin sensitivity. 59 participants completed the intervention (n=28 StandardCHO, n=31 ReducedCHO). AIRg was inversely associated with body fat changes meaning individuals with greater AIRg tended to lose more fat.. Within each diet group, AIRg was inversely associated with fat changes only in the ReducedCHO diet. Insulin-30 did not predict changes in body fat in any model. Post hoc regression analyses were conducted using c-peptide from the IVGTT as the independent variable predicting change in fat mass in both diets. C-peptide performed similar to AIRg, supporting the interpretation that first phase insulin secretion (as opposed to clearance) was driving the association. In conclusion, AIRg was predictive of fat loss during a diet intervention, and the relationship was stronger in participants on the ReducedCHO diet. Insulin-30 may have less predictive power because of higher interindividual variability in LMTT insulin responses. This observation requires more research as the causation cannot be attributed to AIRg.
Recommended Citation
Finn, Amanda, "Insulin Responses, Diet Composition, And Fat Loss" (2024). All ETDs from UAB. 3841.
https://digitalcommons.library.uab.edu/etd-collection/3841