The purpose of the Dairy vs Plant study is to compare the effects of dairy and plant-based alternative products on blood sugar regulation and nutrient quality in adolescents and older adults. We are inviting healthy, non-diabetic participants aged 14-18 and 60-75, both males and females to participate. The study will take place in the Nutrition Intervention Center located at the Department of Nutritional Sciences, University of Toronto St. George campus. Participants will be asked to come to the Nutrition Intervention Center on 3 separate occasions: once for an in-person screening lasting approximately 30min and 2 times for study visits lasting approximately 2.5 hrs each. The entire study will take a minimum of 2 weeks to complete. You will be asked to fast for 12hrs (overnight) prior to each study visit. You will also be instructed to maintain the same dietary and sleep patterns, refrain from exercise and alcohol consumption the days before the study visits. During these study visits, you will be asked to consume either a dairy or a plant-based alternative product, as well as a pizza meal. You will periodically fill out questionnaires rating your feelings and perceptions and provide blood samples through finger pricks and intravenously through forearm to measure blood sugar, insulin, hormones, and amino acids. You will be compensated for your time and travel expenses.

Inclusion Criteria:

• Age 14-18 years old (adolescents) or 60-75 years old (older adults)
• BMI z-score >+1SD, <+2SD (adolescents) or BMI 25-30 kg/m2 (older adults)
• Willing to maintain habitual diet, physical activity pattern, and body weight throughout the study.
• Willing to maintain current dietary supplement use throughout the study. On study visit days, subject agrees not to take any supplements until dismissal from the Nutrition Intervention Center.
• Willing to abstain from alcohol consumption for 24hrs prior to all study visits.
• Willing to avoid vigorous physical activity for 24hrs prior to all study visits.
• Willing to refrain from cannabis use throughout the entire duration of the study.
• Willing to refrain from protein supplement use (e.g. protein powder) throughout the entire duration of the study.
• Understands the study procedures, provides informed consent to participate in the study, and authorizes release of relevant protected health information to the study investigator.

Exclusion Criteria:

• Smoking
• Thyroid problems
• Lactose intolerance and/or allergies, intolerances, or sensitivities to study treatments
• Previous history of cardiovascular disease, diabetes, liver or kidney disease, inflammatory bowel disease, celiac disease, short bowel syndrome, malabsorptive syndrome, pancreatitis, gallbladder or biliary disease
• Presence of gastrointestinal disorder or surgeries within the past year.
• Inability to comply with the experimental procedures and follow our safety guidelines
• Regular breakfast skipping (>3 days a week)
• On a special diet (e.g. ketogenic, Atkins, high protein) or restrained eaters as identified by a score of >20 on the Eating Attitudes Questionnaire
• Difficulties with eating or swallowing
• Fasting blood glucose >5.6mmol/L measured at screening
• Uncontrolled hypertension (systolic blood pressure >120mmHg, diastolic blood pressure >80mmHg) as defined by the average blood pressure measured at screening
• Weight gain or loss of >10lbs in previous three months
• Consuming prescription or non-prescription drug, herbal or nutritional supplements known to affect outcome of the study as per investigator's judgement

IPD will not be shared, as all data will be de-identified and pooled during the analysis. Only researchers directly involved in the study will have access to the data.