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.

Inclusion Criteria:

• 9-18 years, healthy, male.

Exclusion Criteria:

• History of prematurity, chronic illness, were taking any medications known to affect glucose homeostasis, appetite or pubertal development.

Normal weight and overweight/obese adolescent males (n=34) age 9 to 18 were recruited via print advertisement in the local Toronto newspaper. verweight was categorized as in the 85th-95th percentile and obesity in ≥95th percentile.

Individual participant data will not be made available to other researchers.Participant's identities will be kept confidential. Records will be kept in a locked filing cabinet in the Fitzgerald building at 150 College Street, room 305. Access will be restricted to those directly involved with the project, such as the investigator and the co-investigators. Following recruitment and attainment of informed consent, participants will be given an ID # which will be used on all forms and data analysis. Informed consent forms will be kept in a locked cabinet in a locked office, contain participant names. Research records will be identified by initials, ID number, test and date. Results identified by date and ID number will only be entered on password-protected personal computers kept in locked laboratories or offices at the University of Toronto. Any electronic data will be held on encrypted computers and USB sticks for the same period of time.

The experimental beverages contained either 1g of glucose monohydrate (BioShop Canada Inc., Burlington, Ontario, Canada) or 1g of protein (plain whey-protein isolate; BiPro USA., Eden Prairie, Minnesota, U.S.A) per kg of bodyweight. A non-calorie drink was used as control. All beverages were 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. The whey protein and control beverages were sweetened with 0.2g sucralose (Tate & Lyle, Stoney Creek, Ontario, Canada) in order to match sweetness with the glucose beverage.