Tag: 800 Calorie

800 calories per day sits in very-low-calorie diet (VLCD) territory and should not be attempted without medical supervision. The 800-calorie range appears in a few evidence-based clinical protocols – Michael Mosley’s Fast 800, some medically supervised weight-loss programs, and short-term pre-bariatric-surgery preparation – but even in those contexts, licensed clinicians monitor patients through the plan. It is not a lifestyle diet.

Because daily energy needs for most adults sit between 1,600 and 2,400 calories, an 800-calorie intake produces a large deficit that drives fast weight loss in the first weeks – mostly water and glycogen, then fat, and if extended, muscle. Common risks include gallstones, electrolyte disturbance, hair loss, fatigue, dizziness, cold intolerance, and menstrual changes. Contraindications include pregnancy and breastfeeding, adolescence, eating-disorder history, type 1 diabetes, and any condition requiring steady caloric intake for medication management.

The plans in this tag are for reference, not blanket recommendation. If you are considering an 800-calorie plan, work with a licensed clinician who can order labs, monitor your response, and set a re-feed timeline. All content in this tag is medically reviewed by Franco Cuevas, MD. Our nutrition team, including Registered Dietitians Brenda Peralta, Kerly Cordova, and Marita Radloff, reviews the macronutrient split for every 800-calorie plan we publish.