The proposed study looks at the effect of long-term diet modification with or without full-fat dairy products or restrictive eating on body weight, body composition and cardiometabolic markers in healthy overweight/obese men and women.

A total of 93 males and females will participate in the study at the University of Toronto.

At the beginning and after 12 weeks, body weight, composition will be measured through Bodpod scans. Resting metabolic rate and thermogenesis will be measured by indirect calorimetry. Also, fecal samples will be collected for gut microbiome profiling along with blood for glucose, insulin, hormones, triacylglycerol, HbA1c, short-chain fatty acid, red blood cells and FGF21. Urine samples will be collected throughout the study.

A followup session at 16 weeks will reassess previous measures.

Inclusion Criteria:

• BMI: ≥ 27 and ≤ 34.9 kg/m2
• Fasting serum glucose: ≤ 7 mmol/L
• Low ≤1 serving of dairy consumption
• Waist circumference >88cm (women) and >102cm (men)
• Willing to maintain habitual diet, physical activity pattern, and body weight throughout the trial.
• Willing to maintain current dietary supplement use throughout the trial. On test days, participant agrees not to take any dietary supplements until dismissal from the study. Failure to comply will result in a rescheduled test visit.
• Willing to abstain from alcohol consumption for 24 h prior to all test visits.
• Willing to avoid vigorous physical activity for 24 h prior to all test visits.
• Understanding the study procedures and willing to provide informed consent to participate in the study and authorization to release relevant protected health information to the study investigator

Exclusion Criteria:

• Fasting blood glucose > 7 mmol/L
• Triglycerides ≥ 2.3 mmol/L
• Smoking tobacco products and marijuana
• Thyroid problems
• Previous history of cardiovascular disease, diabetes, liver or kidney disease, inflammatory bowel disease, celiac disease, short bowel syndrome, any malabsorptive syndrome, pancreatitis, gallbladder or biliary disease.
• Presence of gastrointestinal disorder or surgeries within the past year.
• Consuming prescription or non-prescription drug, herbal or nutritional supplements known to affect blood glucose or that could affect the outcome of the study as per investigator's judgement.
• Known to be pregnant or lactating, or planning on becoming pregnant in the next 12 months.
• Irregular menstrual cycles (i.e. frequent missed cycles), menopausal or post- menopausal
• Unwillingness or inability to comply with the experimental procedures
• Known intolerance, sensitivity or allergy to dairy products
• Consumption of protein powders/protein supplements
• Extreme dietary habits
• Uncontrolled hypertension as defined by the average blood pressure measured at screening.
• Weight gain or loss of at least 10 lbs in previous three months, and history of childhood overweight or obesity
• Excessive alcohol intake
• Restrained Eaters