Optavia / Medifast
A very-low-calorie meal-replacement plan sold through independent coaches: five packaged “Fuelings” plus one home meal.
Compiled by Nidari Nutrition from the Atlas dataset · pending clinical review by Maryam Shabbir, DN.
This is an Atlas entry — a short reference overview, not one of our long-form diet guides. Educational, not medical advice; personalized and clinically reviewed at your consult.
What is Optavia / Medifast?
Optavia / Medifast is a modern, commercial diet from Baltimore, Maryland, USA. Nidari rates it hard to keep up day to day, and rates the weight of peer-reviewed evidence behind its main claims as moderate.
Family: Modern & Commercial · Origin: Baltimore, Maryland, USA · Era: 1980 · Optavia from 2017 · Difficulty: Hard · Evidence rating: Moderate evidence
Where does Optavia / Medifast come from?
Medifast began in 1980 when Baltimore physician William Vitale formulated meal replacements and sold them to other doctors to prescribe. The company listed publicly in 1993, launched a coach-led direct-selling arm in 2002, and rebranded it as OPTAVIA in 2017. The flagship 5&1 Plan has you eat five company-made “Fuelings” and one meal you cook yourself, supported by a coach who is usually a former customer earning commission on your orders.
Originator: Dr William Vitale (Medifast, 1980); rebranded OPTAVIA in 2017 · Region: Baltimore, Maryland, USA · Era: 1980 · Optavia from 2017 · Atlas map pin: 39.29° N, 76.61° W
How does Optavia / Medifast work?
- Five packaged Fuelings, one home meal
- Eat roughly every two to three hours
- A coach and community for accountability
- Very low calorie intake to force loss
What do you eat on Optavia / Medifast?
✓ Eat freely
- Optavia Fuelings: shakes, bars, soups
- Lean protein: fish, poultry, lean beef
- Non-starchy vegetables and a little fat
✕ Limit or avoid
- Most grains, starches and fruit on 5&1
- Alcohol
- Meals outside the Fueling schedule
Who is Optavia / Medifast for?
The goals this pattern is most often used for. In a consult we confirm whether it actually fits your body and life.
Is there good evidence that Optavia / Medifast works?
Nidari rates the evidence behind Optavia / Medifast’s primary claims as moderate — that is the current weight of peer-reviewed research for those claims, and nothing more.
Two randomised trials support short-term loss: a 2013 International Journal of Obesity trial, and Arterburn et al. (2019), a 16-week trial in which 5&1 produced about 5.7% weight loss against a self-directed control. Both were funded by Medifast, Inc., and several authors reported personal fees from the company. There is no independent long-term trial.
Is Optavia / Medifast safe, and who should avoid it?
The 5&1 Plan supplies roughly 800–1,000 calories a day, below the level generally considered safe without clinical supervision. Documented risks include gallstones, electrolyte disturbance, dehydration, hair shedding, fatigue and loss of lean mass. Optavia coaches are independent contractors, not dietitians or clinicians, and are not medical supervision. Not appropriate in pregnancy, breastfeeding, adolescence, or alongside insulin or sulfonylureas without prescriber review.
How does Nidari adapt Optavia / Medifast?
You are buying American packaged food and a commission-earning coach. If very-low-calorie is genuinely right for you, the supervised medical version has better evidence and no upline — we would rather refer you there.
Book a free 15-minute intro callReady to discuss Optavia / Medifast?
Fifteen minutes with one of our dietitians. We’ll tell you honestly whether Optavia / Medifast fits you — or point you to the diet that does. Halal and home-kitchen ready. No pressure.