The purpose of this study was to determine the effect of acute protein and glucose intake on testosterone levels measured in adolescent boys and determine whether changes in testosterone levels are associated with alterations in short-term food intake. It was hypothesized that 1) ingestion of a protein beverage would result in no change of testosterone levels whereas glucose would result in a significant decrease of testosterone levels 60 minutes after ingestion and 2) decreases of testosterone levels as a result of the glucose preload would predict food intake for boys of similar body size. The first objective was to investigate the effect of an acute protein or glucose drink on testosterone levels and the second objective was to determine whether changes of testosterone levels associate with food intake.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
SINGLE
Enrollment
34
Participants were given 5 minutes to ingest the non-caloric beverage which contained 1.5ml of chocolate extract (Vanilla Food Company, Markham, Ontario, Canada) to account for the flavor differences and mixed with 500ml of water and sweetened with 0.2g sucralose (Tate \& Lyle, Stoney Creek, Ontario, Canada) in order to match sweetness with the glucose beverage.
Participants were given 5 minutes to ingest the beverage which contained either 1g of protein (plain whey-protein isolate; BiPro USA., Eden Prairie, Minnesota, U.S.A) per kg of bodyweight and was flavoured with 1.5ml of chocolate extract (Vanilla Food Company, Markham, Ontario, Canada) to account for the flavor differences and mixed with 500ml of water.
Participants were given 5 minutes to ingest the beverage which contained 1g of glucose monohydrate (BioShop Canada Inc., Burlington, Ontario, Canada) per kg of bodyweight and flavoured with 1.5ml of chocolate extract (Vanilla Food Company, Markham, Ontario, Canada) to account for the flavor differences and mixed with 500ml of water.
University of Toronto
Toronto, Ontario, Canada
Testosterone Change
The first blood draw was taken prior to ingesting the experimental beverage at baseline (0 minutes). Participants were then given 5 minutes to ingest the beverage, and blood was later obtained 20, 35 and 65 minutes after baseline blood draw. Units were measured in ng/dl.
Time frame: 0-65 minutes
Appetite Biomarkers- Glucose
Glucose. Units were measured in mg/dl.
Time frame: 0-85 minutes
Appetite Biomarkers- Glucagon-like peptide-1
Glucagon-like peptide-1. Units were measured in pM.
Time frame: 0-85 minutes
Appetite Biomarkers- Active Ghrelin
Active Ghrelin. Units were measured in pg/ml.
Time frame: 0-85 minutes
Appetite Biomarkers- Insulin
Insulin. Units were measured in uIu/ml.
Time frame: 0-85 minutes
Subjective Appetite- Determination to eat
Visual Analog Scales were employed to assess subjective appetite based on the Determination to Eat. Units were measured in mm (based on a 100mm scale).
Time frame: 0-85 minutes
Subjective Appetite- Hunger
Visual Analog Scales were employed to assess subjective appetite based on feelings of Hunger. Units were measured in mm (based on a 100mm scale).
Time frame: 0-85 minutes
Subjective Appetite- Fullness
Visual Analog Scales were employed to assess subjective appetite based on feelings of FullnessUnits were measured in mm (based on a 100mm scale).
Time frame: 0-85 minutes
Subjective Appetite- Prospective Food Consumption
Visual Analog Scales were employed to assess subjective appetite based on Prospective Food Consumption. Units were measured in mm (based on a 100mm scale).
Time frame: 0-85 minutes
Food Intake
Participants were provided an ad libitum pizza meal. The participants were instructed to eat during the next 20 min until they were comfortably full. Based on the participant preferences determined during screening, two varieties of Deep 'N Delicious 5-inch-diameter pizza were provided for consumption; pepperoni and three-cheese pizzas (McCain Canada Ltd., Florenceville, Ontario, Canada). Units were measuring in kcal.
Time frame: 65-85 minutes
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