Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â ABSTRACT
PRINCIPAL INVESTIGATOR:Mary Miles
PROJECT TITLE: Sugar-sweetened beverages decrease benefits of exercise in overweight adults
PROGRESS TOWARDS GOAL: Duration of time covered by this report: The PI was notified of the Round 2 Pilot Grant Award in October of 2014 and the period of funding began 12/1/2014. Thus, this progress report describes progress toward our aims from mid-October 2014 until April 7, 2015, or approximately 5.5 months. Specific aims summarized in this report: Aim 1: To identify whether SSB ingestion attenuates exercise-induced increases in insulin sensitivity (IS) in overweight individuals. Aim 2: To determine the influence of SSB ingestion on inflammatory and endocrine mediators of IS and glycemic control (ability to keep blood glucose concentrations in homeostasis). Progress toward aims: Research design and participants: To achieve our aims, a randomized, balanced, crossover design is being used to compare three experimental treatments within participants: 1) no exercise, no SSB, 2) exercise, no SSB, and 3) exercise, SSB. Each participant will serves as her/his own control and undergo all experimental conditions. At this time, 15 participants have been enrolled, 10 participants have completed the study (8 women), three participants are in progress (2 women), and two participants (2 women) dropped out after the baseline visit but prior to completing any of the experimental conditions (one for difficulty in scheduling and one for a health change unrelated to the study). We proposed enrollment of 24 participants (12 women). Our original proposal was for all participants to be women, however, a recommendation from NIH to us in December was to enroll equal numbers of women and men. As a result, we began with women and then added men, which accounts for the greater number of women enrolled to date. Going forward, enrollment will focus on men and we anticipate meeting our target enrollments prior to June 30, 2015. Status of measurements and analyses: Our top priority has been the recruitment, enrollment and testing of research participants. Laboratory assays for insulin, glucagon, and inflammation variables are in progress. In addition to baseline measurements to describe the participants completed to date, we report here the lipid data Preliminary findings: We are successfully recruiting overweight and class I obese participants who are successfully completing our research protocol. Characteristics of the 10 participants who have completed the study: age 33.1 Â± 10.8 (range 18-52) y; BMI 29.4 Â± 2.6 (range 26.2-33.6) kg/m2; body fat 37.9 Â± 6.9 (range 28.4-48.6) %. Contrary to our hypothesis, we have found that the glycemic response in the SSB condition is lower than in the non-SSB condition. On the morning following exercise or control with or without SSB, an OGTT was performed with blood samples and measures of carbohydrate and fat oxidation before and 15, 30, 45, 60, 90, and 120 minutes after glucose ingestion. Area under the curve (AUC) for glucose for the early phase (0-60 minutes) of the OGTT was lower (p=0.019) in the SSB compared to NO-SSB condition. No differences across conditions was measured in the late phase AUC (60-120 minutes). Our interpretation of this finding will depend on the response of glucoregulatory hormones, insulin and glucagon, measured at the same time points. Metabolic flexibility may be an underlying factor to consider when more data are available. We observed that utilization of fat as a fuel at rest in the fasted state provided only 71.9% of energy on the morning after the SSB exercise condition compared to 85.3% of energy on the morning after the NO-SSB exercise condition. This may be an indication that consumption of sugar had the effect of downregulating fat metabolism and upregulating glucose metabolism at a time when reliance fat should be maximal. That is, we suspect that metabolic flexibility may be decreased after SSB ingestion. This would be a negative consequence for metabolic health. We look forward to learning more about our unique findings as as our investigation proceeds.