Vitamin D prevalence information and baseline labs and anthropometrics will be obtained from all patients who agree to participate in the study; however, bioelectrical impedance analysis will not be performed in patients under 5 years. Patients between the ages of 5 and 11 years who have a 25-hydroxyvitamin D below 21 ng/mL will be invited to participate in vitamin D supplementation portion of the study. These patients will be treated with vitamin D3 supplementation of either 2000 IU once a day or 6000 IU once a day. Dose will be determined by a set dosing schedule. Each provider will be assigned a dosing schedule and dosing schedules that will change every 3 months over 2 years. The dosing schedule can be found in the study documents section. This study design is intended to minimize bias based on provider or season. Eligible patients who agree to participate in the study will purchase the prescribed dose of vitamin D3, which is an over the counter medication. Vitamin D3 is supplied over the counter as drops, liquid, chewable tablets, gummies, tablets or capsules and parents will select the form that is easiest for their child to take. They will supply us with a picture of the vitamin D3 label so that we can ensure they are taking the appropriate dose and form of vitamin D. They will take the prescribed dose every day for three months. Patients will get weekly reminder calls to ensure that they are taking the supplement as prescribed. At the end of three months they will return for their scheduled clinic appointment. Weight, height, waist circumference and percentage body fat will be measured and labs will be redrawn including 25-hydroxyvitamin D glucose, insulin, hemoglobin A1c, lipid panel, hepatic function panel and basic metabolic panel and the research labs described above will be drawn as well. At the end of 3 months if vitamin D is 21 ng/mL or above they will be advised to take vitamin D 1000 IU once a day; if their vitamin D continues to be below 21 ng/mL they will be advised to continue their current dose of vitamin D.