The investigators primary objective is to evaluate the effect of a 6 month (3 days/wk) supervised, progressive RT program with increased daily milk intake in untrained adolescents on measures of body composition and cardiovascular risk factors. The investigators hypothesize that milk supplementation will produce significantly greater favorable changes in all body composition measures compared with RT + carbohydrate and control.

We will recruit 150 healthy, adolescent middle school boys and girls (grades 7 through 9), BMI > 50th percentile < 98th percentile, who will participate in 6 months of supervised resistance training (3 days/wk) and will be randomized to one of 3 groups: RT + milk, RT + isocaloric carbohydrate, RT only (control). Both physical activity and diet outside the study protocol will be carefully monitored. Measurements will be completed at baseline 3 months and upon completion of the training protocol at 6 months.

Inclusion Criteria:

1. Middle school student (Grades 7-9)
2. BMI > 50th percentile - < 98th percentile
3. No resistance training in the past 6 months.
4. Endurance training (running, cycling, swimming, walking for exercise etc) not more than 3 hr per week, as assessed by screening questionnaire.
5. Weight stable (+/- 4.5kg) for 3 months prior to intake.
6. Willing to be randomized to one of the 3 study groups.

Exclusion criteria:

1. Individuals with contraindications based on review of health history by the investigators, including blood pressure, lipid profile, glucose, and insulin, and abnormal values obtained in a 24 item blood panel, such as electrolytes, liver function, etc. These individuals will be referred to their primary care physician for further evaluation and to obtain permission to participate. The following cut-points will be used for cardiovascular and metabolic parameters: dyslipidemia- lipids (cholesterol > 240 mg/L; triglycerides >500 mg/L), hypertension- systolic blood pressure > 140 mmHG or diastolic blood pressure > 90 mmHG, diabetes - fasting glucose from venous plasma fasting glucose > 126 mg/dL.
2. Medications that could affect metabolism such as cardiac drugs, thyroid, steroids, insulin, beta blockers, SSRI's, birth control pills, etc.
3. Current use of smoking/tobacco products or initiation of smoking/tobacco during the study.
4. Eating disorders as determined by screening questionnaire
5. Adherence to specialized diet regimes, vegetarian, macrobiotic, etc.
6. Food allergies, particularly lactose intolerance.
7. Treatment for psychiatric illness of chemical dependency within the previous 6 months.
8. Pregnancy or lactation.
9. Dietary intake of ≤800 mg calcium and ≤1 servings of milk per day as assessed from 3 -24 hr diet recalls (2 week-days, 1 week-end day) conducted at baseline.