Is there a difference in the ‘hunger’ hormone between Pacific Island and New Zealand European populations?

This is a non-therapeutic mechanistic physiological study. All the following measurements and tests described will be conducted by a trained human physiologist staff member. An initial familiarization visit will be conducted (~45 min) where an investigator will explain the nature of the procedures, answer any questions, and obtain written informed consent (as described above). Once consent has been obtained, assessment of the inclusion/exclusion criteria will be performed. Provided the inclusion criteria are met and there are no exclusion criteria, the participant will be enrolled into the study. Anthropometric (height, weight, hip-to-waist ratio, %body fat), demographic, clinical information will be collected. More specifically the following questionnaires will be completed (all attached); 1) General Health Screening Questionnaire, 2) Quality of Life [EQ-5D-5L]; 3) International Physical Activity Questionnaire [IPAQ], and 3) 5-Factor Satiety Questionnaire. Following this, participants will be familiarized with the study procedures. Microneurography will not be performed on this visit, but fully described and explained. Participants will attend the laboratory for one experimental visit. Experimental sessions will be conducted at the Human Cardiorespiratory Physiology Laboratory, Clinical Research Centre Facility, Faculty of Medical and Health Sciences. The experimental visit will begin at ~9am and last ~2-3 hours. It will be scheduled ~2-7 days after the initial familiarization / screening visit. The procedures will be reviewed again with the participant and remaining questions answered. Prior to the study visit participants will have been provided with a participant information leaflet, advising them of the following pre-study stipulations: • No food intake overnight (i.e., ~8 hours prior to the study). • No caffeine (e.g., coffee, coke, red bull) for 12 hours before the study. • No alcohol on the day before the study and the day of the study. • No exercise after 8:00pm the evening before the study and no exercise on the day of the study. • No ‘over the counter’ (e.g., paracetamol) or prescribed medications (e.g., beta-blocker, ACE inhibitors) on the morning of the study. At the experimental visit a blood sample will first be taken from an antecubital vein (~20 ml). Participants will be escorted to a phlebotomist located within the Clinical Research Unit at the University of Auckland ~200 meters from the laboratory. Once back in the laboratory, participants will then be asked to lay in a semi-recumbent position on a bed and assessments will then be made of; arterial stiffness and brachial artery FMD. Arterial stiffness measures requires a lightweight probes place at the carotid (neck) and radial (wrist) arteries and a cuff positioned around the upper thigh. Flow mediated dilatation (FMD) will be used to examine brachial artery function using ultrasound. This simply involves the inflation (5 min, 200 mmHg) and subsequent deflation of a standard blood pressure cuff around the upper arm (5 min). Participants will then be instrumented for the measurement of heart rate, blood pressure, ventilation, and sympathetic nerve activity recordings (described below). Standardized autonomic function tests will then be administered. This will involve; 1) Resting baseline (10 min) 2) Slow deep breathing at 6 breaths/min (5 min) 3) Valsalva’s maneuver (3 x 30 s) 4) Hyperoxia (5 x 60 s)