Patient description: A 67-year-old healthy woman came to the clinic to have her flu shot in early October. She works at a rehab center and has no underlying disease. It is her first vaccination this year. she is menopausal and has 4 children. She does not some. She takes daily multivitamins and anti-hypertensive drugs. She exercises regularly for 30 minutes a day at least 5 days a week. She has no allergies to any food or drugs.

Clinical trial eligibility criteria: eligible ages (years): 18.0-85.0,  Intermittent Fasting Obesity, Morbid Comorbidities and Coexisting Conditions Weight Loss Fluid Retention 1. Subjects with complicated obesity grade 2 or higher (Body Mass Index [BMI]>35kg/m2), i.e., obesity associated with renal failure with eGFR<60cc/min or heart failure with preserved ejection fraction (EF) (≥50%) and clinical evidence of fluid retention evidenced by the use of loop diuretic, or the presence of peripheral edema; or treatment in congestive heart failure clinics or history of admission to the hospital for heart failure during the past 3 years; OR • b. Subjects with complicated obesity, grade 2 or higher (BMI>35 kg/m2) [with renal failure as defined above-delete this requirement] and at least one of the following comorbidities: 1) Uncontrolled hypertension despite the use of at least 3 drugs administered at their maximal or close to maximal dose 2) Severe sleep apnea (based on a sleep lab report) 3) Pulmonary hypertension 4) Coronary heart disease 5) Type 2 diabetes mellitus 6) History of stroke (> 3 months prior to the recruitment to the trial) 2) Subjects who failed to lose weight on standard treatment, refuse standard medical treatment or are judged as unable to tolerate/unsuitable to receive standard medical treatment to lower body weight and in whom bariatric surgery is deemed unacceptable due to excessive surgical risk by the referring physician and/ or the PI and / or the patient and fulfill the following 1. Wish to fast 36 hours, twice a week, over three months 2. Committed to attend the clinic at least once a week and perform blood tests every 2-14 days, as detailed in the protocol. 3. Are well trained in-home glucose monitoring and are willing to monitor glucose levels during the fasting days. 4. Are well trained in-home monitoring of blood pressure and are willing to measure blood pressure twice a day during the fasting days. 5. Own and control a dependable means of 24/7 communication device, eg, cell phone, and are committed to avail this route of communication to the study staff  Severe renal failure (eGFR<20cc/min) 2. Liver disease other than non-alcoholic fatty liver disease or cardiac cirrhosis or any liver disease with aspartate aminotransferase (AST), alanine aminotransferase (ALT) or alkaline phosphatase levels>3 times of the upper limit of the normal range, albumin< 3.5 gr% or direct bilirubin>1.2 mg%. 3. Cognitive impairment assessed by a Mini-Mental State Exam (MMSE) score < 24 4. Living in a single household (caretaker is allowed) 5. Age less than 18 or >85 years 6. Pregnancy or intention to conceive or female at the reproductive age not using birth control means. 7. History of documented hypoglycemia during the past year despite attempted adjustment of treatment. 8. Unintended weight loss > 2kg over the past 2 months. 9. The initiation, within the study period of any one of the following medications, including topiramate, lyxumia, byetta, bydureon, belviq, Xenical, victoza, saxenda, trulicity, semaglutide or any other glucagon-like peptide-1 (GLP-1) analog. However, subjects already treated with these agents before the initiation of the trial may be included provided that the medication has been started at least 4 months prior to the beginning of the study and that weight loss during the 2 months preceding the trial did not exceed 2 kgs. 10. A subject who must use drugs whose use is not recommended on an empty stomach and in whom this qualification appears, in the investigator's opinion more critical than the potential chance to lose weight and excrete excess bodily fluids