Dairy intake and metabolic health in teens and older adults

The Effect of Dairy Intake on Body Weight and Composition and Metabolic Health in Adolescents and Seniors

This project will test whether eating three servings of dairy each day helps overweight or obese teens (15–18) and older adults (60–80) improve weight, body composition, and metabolic health over six months.

Quick facts

• Phase: Not applicable
• Study type: Interventional
• Enrollment: 240 (estimated)
• Ages: 14 Years to 80 Years
• Sex: All
• Sponsor: University of Toronto (Academic / other)
• Locations: 2 sites (Toronto, Ontario and 1 other locations)
• Trial ID: NCT06879652 on ClinicalTrials.gov

What this trial studies

This randomized intervention assigns eligible overweight or obese adolescents and older adults to either a high-dairy group (three servings daily of milk, yogurt, and cheese) or a low-dairy control group (<1 serving/day). All participants receive biweekly sessions with a registered dietitian to follow Canada's Food Guide and support adherence. Clinical visits at baseline, 12 weeks, and 24 weeks collect anthropometry, body composition, fasting glucose/HbA1c, and other metabolic measures; dietary intake is monitored to track compliance. The trial is conducted at the Nutrition Intervention Center in the Department of Nutritional Sciences at the University of Toronto.

Who should consider this trial

Good fit: Ideal candidates are overweight or obese adolescents aged 15–18 (BMI z-score >+1 to <+2) or adults 60–80 with BMI 25–34.9 kg/m2, prediabetes (fasting glucose 5.6–6.9 mmol/L), and ability to attend in-person visits and follow Canada's Food Guide.

Not a fit: Patients with diagnosed diabetes (fasting glucose ≥7 mmol/L), uncontrolled hypertension, current smokers, or those with dairy allergy/intolerance or unwilling to follow the diet are unlikely to benefit.

Why it matters

Potential benefit: If successful, this approach could produce modest improvements in weight, body composition, and metabolic markers and potentially reduce progression to diabetes.

How similar studies have performed: Previous randomized and observational studies show mixed but sometimes modest benefits of increased dairy on weight and metabolic markers, so the approach has limited but not conclusive prior support.

Eligibility criteria

Inclusion Criteria (long-term Study):

* Age 15-18 years old (adolescents) or 60-80 years old (seniors)
* BMI z-score \>+1SD, \<+2SD (adolescents) or BMI 25-34.9 kg/m2 (seniors)
* Waist circumference \> 80 cm for women and \> 94 cm for men (seniors)
* FBG 5.6-6.9 mmol/L (prediabetes)
* Willing to follow Canada's Food Guide
* Willing to maintain current dietary supplement use throughout the study.
* Willing to abstain from alcohol consumption for 24 hours before all test visits.
* Willing to avoid vigorous physical activity for 24 hours before all test visits.
* Understands the study procedures and is willing to provide informed consent by the parent/guardian and assent by participant to participate in the study and authorization to release relevant protected health information to the study investigator.

Exclusion Criteria:

* Fasting BG ≥ 7 mmol/L
* Blood pressure systolic ≥ 130mmHg or diastolic ≥ 80mmHg (adolescents) or systolic ≥ 140 mmHg or diastolic pressure ≥ 90 mmHg
* Smoking (tobacco and/or cannabis product use in the last 6 months)
* Thyroid problems
* History of CVDs, diabetes, liver or kidney disease, inflammatory bowel disease, celiac disease, short bowel syndrome, any malabsorption syndrome, pancreatitis, gallbladder, or biliary disease.
* Presence of gastrointestinal disorder or surgeries within the past year.
* Use of the prescription or non-prescription drugs, herbal or nutritional supplements known to affect the outcome of the study as per the investigator's judgment (including prebiotics and probiotics).
* Known to be pregnant, lactating, or not postmenopausal for at least a year and/or is taking hormonal treatments
* Unwillingness or inability to comply with the experimental procedures
* Known intolerance, sensitivity, or allergy to dairy, gluten, or any other study treatments.
* Consumption of protein powders/supplements
* Extreme dietary habits (e.g., Atkins diet, very high-protein diets, etc.)
* Weight gain or loss of \> 5% in the previous three months.
* Excessive alcohol intake (more than 2 drinks per day or 9 per week)
* Restrained eating, identified by a score of ≥11 on the Eating Habits Questionnaire

Inclusion Criteria (short-term study):

* 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 (short-term study):

* 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

Where this trial is running

Toronto, Ontario and 1 other locations

• Department of Nutritional Sciences — Toronto, Ontario, Canada (Recruiting)
• Nutrition Intervention Center — Toronto, Canada (Not_yet_recruiting)

Study contacts

• Principal investigator: G Harvey Anderson, Ph.D. — University of Toronto
• Study coordinator: Shekoufeh Salamat, Ph.D.

Conditions Dairy Consumption; Metabolic Health; Obesity Prevention; Dairy intake; Obesity; Type2 Diabetes; HbA1c; BMI z-score