Diabetes Prevention Program (METFIT) in Reducing Insulin Resistance in Stage I-III Breast Cancer Survivors

Inclusion Criteria:

* Women who have been treated definitively for early stage breast cancer (I-III) and are 60-180 days from completion of chemotherapy, radiation and surgery regardless of hormonal status
* Demonstrated at least a 10% weight gain since being diagnosed with breast cancer
* Demonstrated IR by having a Homeostatic Model Assessment of Insulin Resistance (HOMA-IR) score of \>= 2.0
* Demonstrated IR manifested by meeting criteria for metabolic equivalent (MetS) as defined by modified criteria of the National Cholesterol Education Program Adult Treatment Panel (NCEP ATP III) (2005 version) and the World Health Organization (WHO) which includes:

  * Dysregulation of glucose homeostasis demonstrated by a glycosylated hemoglobin (HbA1c) \>= 6.5%; OR fasting plasma glucose \>= 126 mg/dl (7.0 mmol/L) OR random plasma glucose \>= 200 mg/dL (11.1 mmol/L)
  * Plus two of any of the following:

    * Waist circumference in men \>= 40 inches and in women \>= 35 inches
    * Elevated triglycerides \>= 150 mg/dL
    * Low high-density lipoprotein (HDL) cholesterol in men \< 40 mg /dL and in women \< 50 mg/dL or taking statin medication
    * Elevated blood pressure defined by a systolic pressure \>= 130 of a diastolic pressure \>= 85 mm Hg or taking anti-hypertensive medication
    * Elevated fasting glucose \>= 110 mg/dL
* Non-smoker (last use 6 months prior to enrollment into the study)
* Documented informed consent of the participant and/or legally authorized representative
* Willingness to make substantial changes in their dietary and physical activity behavior
* Willingness to attend at 70% of the intervention sessions and 100% of the blood draws
* The effects of IF on the developing fetus of breast cancer survivors are unknown. For this reason, women of child bearing potential must agree to use adequate contraception (hormonal or barrier method of birth control or abstinence) prior to study entry and for six months following duration of study participation. Should a woman become pregnant or suspect that she is pregnant while participating in the trial, should inform her treating physician immediately
* Willingness to weigh themselves weekly
* Willingness to wear a subcutaneous continuous glucose monitor
* Access to an electronic virtual teleconferencing device and capacity to utilize electronic teleconference technology

Exclusion Criteria:

* Use of any medication to treat diabetes mellitus
* Type 2 diabetes
* History of myocardial infarction or congestive heart failure within the previous 12 months prior to being screened for participation in the study
* Cardiovascular, respiratory or musculoskeletal disease or joint problems that preclude moderate physical activity
* Unstable cardiac disease as defined by one of the following:

  * Cardiac events such as myocardial infarction (MI) within the past 6 months
  * New York Heart Association (NYHA) heart failure class III-IV
  * Uncontrolled atrial fibrillation or hypertension
* History of vascular disease (e.g. deep vein thrombosis, stroke) within six months of starting the intervention
* Clinically significant uncontrolled illness
* Women who are pregnant or breastfeeding
* Any other condition (including psychosocial condition) that would, in the investigator's judgment, contraindicates the patient's participation in the clinical study due to safety concerns with clinical study procedures
* Any other condition that would confound study results
* Prospective participants who, in the opinion of the investigator, may not be able to comply with all study procedures (including compliance issues related to feasibility/logistics)