The goal of this clinical trial is to compare features of metabolism in healthy, young adults after they consume four meals of differing fat quantity. The main question this trial aims to answer is how does increasing fat quantity impact glucose tolerance, glucose and insulin metabolism, and hormones involved in hunger. Participant will consume four meals consisting of either 20, 40, 60, or 80% energy from fat.

The long-term consumption of high-fat foods can lead to unhealthy changes in the functioning of the body, giving rise to metabolic diseases such as type 2 diabetes. Similarly, short-term high-fat diets have also been shown to disrupt how the body performs but there is a lack of information regarding how a single high-fat meal can disrupt metabolism. Comparing meals of different fat quantity, without changing the overall energy intake (calories), will help us understand the short-term effect of fat ingestion on the functioning of the body and whether increasing the amount of fat in a meal is related to the level of dysfunction in the body. Therefore, the investigators will provide participants with four meals of varying fat quantity and in the period following the meal, the investigators will take blood samples to determine any changes that occur in the body in response to different levels of fat.

Inclusion Criteria:

• BMI between 18.5 and 30.0 kg/m2
• Weight stable for the past 6 months (± 2kg)
• VO2max values within a below average to above average range (38-50 mL/kg and 35-47 mL/kg for 18-25 year old males and females respectively. 35-48 mL/kg and 34-45 mL/kg for 26-35 year old males and females respectively)
• Fasting blood glucose <6.0 mM
• Resting blood pressure <140/90 mmHg
• Taking second generation oral contraceptives (females only)

Exclusion Criteria:

• Smoking
• Diabetes, cancer, or other metabolic disorders
• Cardiac or gastrointestinal problems
• Infectious disease
• Barium swallow or nuclear medicine scan in the previous 3 weeks
• Follow a strict vegan diet
• Pregnant or breastfeeding (females only)
• Diagnosis of polycystic ovary syndrome (females only)

IPD will not be available to other researchers

Participants and investigators will not know the fat quantity of the meal that is being consumed or the order in which the meals are provided to the participant. A non-investigator member of the research team will be responsible for creating the meals and keeping track of which meals are being consumed.