In addition to its role as the major regulator of glucose uptake into peripheral tissues, the hormone insulin is also a primary regulator of fat storage and fat burning of the body. Mechanistic animal studies have shown that high insulin may be the initial trigger for weight gain and be the proximal cause of obesity. There is currently no quick or non-invasive way of measuring insulin as research and clinical techniques require collection of a blood sample followed by a complicated and costly biochemical assay. The investigators will test the hypothesis that insulin levels can be accurately measured in saliva in humans following meals that elicit high and low blood insulin responses. Findings will help determine if insulin can be use as a valid fluid to track insulin changes in humans.

Lean and obese healthy participants will consume both a high carbohydrate meal and a low carbohydrate meal designed to elicit different insulin responses on two separate occasions. Blood samples and saliva samples will be collected for 2 hours following each meal and insulin will be measured in both plasma and saliva. The relationship between plasma and saliva insulin following the two meals will be assessed.

Inclusion Criteria:

• Body mass index between 18.5-24.9 or over 30.0 kg/m2

Exclusion Criteria:

• Diabetes or other medical conditions affecting glucose or insulin levels
• Smoker
• Competitive athlete
• Vegan or vegetarian