Experts › Eating › Mark Hyman

EatingFood as medicineEvidence: mixed

Mark Hyman

Physician (MD, family medicine) · functional medicine author · co-founder and chief medical officer of Function Health

Treat food as medicine: a plant-rich, low-sugar 'Pegan' diet, regular exercise, good sleep and stress care, guided by lots of lab testing.

In short

  • Strength 3–4 × a week
  • Mostly plants, little sugar
  • 7–8 h sleep, regular bedtime
Build my plan in Hyman’s style
Words explained (3)
Intervals
Short hard efforts with easy recovery in between, such as 30 seconds fast, 90 seconds slow.
Creatine
A well-studied supplement that supports strength and muscle.
Polyphenols
Natural plant compounds in foods such as berries, tea, coffee, cocoa and olive oil.

At a glance

Strength 30%Easy cardio 25%Intervals 30%Mobility & stability 15%

Training focus: our estimate from what they recommend.

Pegan diet
Signature habit
30–50 g shake after training
Protein
Food as medicine
Training style
Mixed
Overall evidence

Background

Mark Hyman studied Asian studies at Cornell University (BA, 1982) and medicine at the University of Ottawa (MD 1987), then trained in family practice in Ottawa and in Santa Rosa, California. He began as a family doctor in rural Idaho and later worked as an emergency physician in Massachusetts.

From 1996 to 2004 he was co-medical director at the Canyon Ranch resort in Lenox, Massachusetts. He then opened his own practice there, The UltraWellness Center, which he still lists as founder and director. He is a long-time leader in the Institute for Functional Medicine, where he is board president for clinical affairs.

In 2014 he set up and led the Cleveland Clinic Center for Functional Medicine. He stepped down as its director in 2023 and the clinic now lists him as head of strategy and innovation for the centre.

He became widely known through more than a dozen popular diet and health books, including Eat Fat, Get Thin (2016), Food: What the Heck Should I Eat? (2018) and Young Forever (2023), and through his podcast, The Dr. Hyman Show. In 2021 he co-founded Function Health, a membership blood-testing company, where he is chief medical officer.

Known for

  • The Pegan diet (paleo + vegan blend)
  • Popularising functional medicine
  • Food-as-medicine and food policy advocacy
  • Function Health lab-testing memberships
  1. 1987Medical degree, University of Ottawa
  2. 1996Became co-medical director at Canyon Ranch, Lenox (to 2004)
  3. 2014Founded and directed the Cleveland Clinic Center for Functional Medicine
  4. 2016Published Eat Fat, Get Thin
  5. 2018Published Food: What the Heck Should I Eat?, setting out the Pegan diet
  6. 2021Co-founded Function Health (chief medical officer)
  7. 2023Published Young Forever; stepped down as director of the Cleveland Clinic centre

Core ideas

  1. Most chronic disease is driven by diet and lifestyle, so food should be the first medicine.
  2. Sugar, refined starch and ultra-processed food are the main dietary problems, not dietary fat.
  3. Eat mostly plants (around three-quarters of the plate), with good-quality animal protein and healthy fats.
  4. Look for root causes of symptoms rather than only treating them, often using extensive lab tests.
  5. Ageing is shaped by known biological 'hallmarks' that can be slowed with exercise, sleep, stress care, diet and some newer therapies.
  6. Muscle and protein matter more as we age.

How Hyman lives

On his own podcast (aged 63 at the time) and in interviews, Hyman has described a routine built around near-daily exercise, a protein shake, a plant-heavy diet, many supplements and a range of experimental therapies.

4–6×
cardio/interval sessions a week, ~30 min (reported)
3–4×
strength sessions a week, ~30 min, mostly bands (reported)
7–8 h
sleep target, in bed around 10 pm (reported)
12–16 h
overnight fast, varies by source (reported)
  1. WakingA large glass of water with electrolytes, then coffee; green tea through the day.
  2. MorningMeditation and breathwork; morning supplements such as green tea extract, turmeric and broccoli extract.
  3. Late morningAbout 30 minutes of band-based strength work, then steam and a cold plunge when possible.
  4. After trainingA 'healthy aging shake' with goat whey protein, 5 g creatine, berries and add-ins, which usually lasts him to lunch.
  5. LunchA large 'fat salad': greens, avocado, nuts or seeds, olive oil and small oily fish such as sardines or salmon.
  6. EveningMagnesium, blue-light-blocking glasses, a dark quiet room; sleep tracked with a ring and watch.

The protocol

Training

  • Strength training 3–4 times a week, about 30 minutes, mainly resistance bands and moderate weightsStrong evidence
  • Aerobic or interval training 4–6 days a week, about 30 minutes (cycling, tennis, hiking, swimming)Strong evidence
  • Yoga a couple of times a week plus a little stretching most daysSome evidence
  • Avoids very heavy lifting as he ages to limit injury riskPersonal habit
  • Hypoxia (low-oxygen) training with a machine or maskPersonal habit

Go deeper: Strength (Brad Schoenfeld) · Heart & fitness (Benjamin Levine, Martin Gibala) · Mobility & balance (Mike Fitch, Jules Mitchell)

Eating

  • Pegan diet: about 75% of the plate from plants, mostly non-starchy vegetablesStrong evidence
  • Cut sugar, refined flour and ultra-processed foodsStrong evidence
  • 1–2 cups of cruciferous vegetables (broccoli, cabbage etc.) a daySome evidence
  • Healthy fats from olive oil, avocado, nuts, seeds and small oily fishStrong evidence
  • Avoid gluten and most dairy, even without intolerancePersonal habit
  • Daily overnight fast of 12–16 hoursSome evidence

Go deeper: Eating (Tim Spector, Chris van Tulleken)

Supplements

  • Protein shake after training: 30–50 g whey (goat) plus 5 g creatineStrong evidence
  • Vitamin D, fish oil, a multivitamin and magnesium at nightSome evidence
  • NMN (about 900 mg a day), urolithin A, quercetin, curcumin and similar 'longevity' compoundsPersonal habit
  • His own branded gut supplement (prebiotics, probiotics, polyphenols)Personal habit

Sleep & recovery

  • 7–8 hours of sleep with a regular bedtime around 10 pmStrong evidence
  • Dark, quiet bedroom with eye mask and earplugsSome evidence
  • Blue-light-blocking glasses in the eveningPersonal habit
  • Steam or sauna and cold plunge most daysPersonal habit
  • Red light therapy at homePersonal habit

Go deeper: Sleep (Matthew Walker, Colleen Carney)

Stress & mind

  • Meditation once or twice a day plus breathworkSome evidence
  • As much time in nature as possibleSome evidence
  • Regular time with friends and familySome evidence
  • Regular massagePersonal habit

Go deeper: Stress & connection (Elissa Epel, Robert Waldinger)

Strong evidence = trials or large studies · Some evidence = smaller or observational studies · Personal habit = their own choice, little evidence · Doctor only = prescription or blood-test dosing, never in your plan.

Where Hyman changed course

In March 2016, shortly after Eat Fat, Get Thin came out, Hyman publicly admitted he had misreported results from Dean Ornish's heart study in the book and said he had corrected later printings and the digital edition, while keeping his overall view that fat is not the main problem.

Their best-known claims, fact-checked

Partly supported

Sugar and refined carbohydrates, not dietary fat, drive weight gain and heart disease.

Cutting refined carbs and ultra-processed food helps, but controlled trials show saturated fat raises LDL cholesterol and heart risk, and high-fat diets do not beat lower-fat diets for long-term weight loss.

Red Pen Reviews, review of Eat Fat, Get Thin, 2021

Partly supported

A plant-rich Pegan diet (about 75% plants, low sugar, quality protein and fats) is a healthy way to eat.

Its core resembles the well-studied Mediterranean pattern, but cutting out gluten and most dairy for everyone has no strong evidence and can make calcium and other nutrients harder to get.

Carrie Dennett, Washington Post, 2019; Alyssa Pike, Food Insight (IFIC); Estruch et al., NEJM 2018

Unproven

Functional medicine gets better results than conventional care by treating root causes.

The main study is a non-randomised 2019 Cleveland Clinic cohort with small, short-lived gains in self-reported health; critics note patients differed at the start.

Beidelschies et al., JAMA Network Open 2019; Gorski, Respectful Insolence 2019

Unproven

Large lab-test panels in healthy people help find problems early and guide prevention.

There is little evidence that broad lab panels in healthy adults improve health outcomes; critics warn that buying tests without medical guidance risks misinterpretation and false positives.

Adrian Chavez, Katie Couric Media, 2026

Supported

Strength training and enough protein are key to healthy ageing.

Resistance training and adequate protein are well supported for keeping muscle and function in older age.

Mainstream geriatric and exercise guidance (e.g. WHO physical activity guidelines, 2020)

Not supported

Gluten can cause autism.

There is no good evidence that gluten causes autism, and the NHS does not recommend gluten-free diets for autism.

BBC World Service investigation of The Diary of a CEO, December 2024; The i Paper (Clare Wilson), 2024

Commercial ties: Hyman co-founded and is chief medical officer of Function Health, a membership lab-testing company, and sells supplements and his own branded products through his website; he also earns from books, his podcast and media work.

Hyman’s style in your plan

Choose “Follow one expert” and we keep this balance of training and the methods above, then fit them to your age, your available time and your health screen.

What goes into your plan

  • Strength training 3–4 times a week for about 30 minutes, using bands or moderate weights.
  • Aerobic or interval exercise most days, about 30 minutes, in activities you enjoy.
  • Fill most of your plate with vegetables, including 1–2 cups of cruciferous vegetables a day.
  • Cut back sharply on sugar, refined flour and ultra-processed foods.
  • Get healthy fats from olive oil, nuts, seeds, avocado and oily fish.
  • Aim for 7–8 hours of sleep with a regular bedtime and a dark, quiet room.

What we leave out, and why

  • Lab-test panels and supplements dosed from them (e.g. B vitamins for homocysteine): only with your own doctor.
  • NMN, urolithin A and similar 'longevity' supplements: little human evidence of benefit.
  • High-dose vitamin D stacks (around 7,000 IU a day): above the usual safe upper limit without testing and medical advice.
  • Peptides, stem cells, exosomes, plasmapheresis and ozone therapy, which he describes using himself: experimental and not proven safe.
  • Avoiding gluten and dairy without a diagnosed intolerance: no strong evidence and can reduce calcium intake.
  • Daily cold plunges and hypoxia training: limited evidence and possible heart strain for some adults over 50.
Build my plan in Hyman’s styleCompare with other experts

The research behind it

Functional medicine at Cleveland Clinic

Patients at Hyman's former centre reported slightly bigger gains in physical well-being at 6 months than primary-care patients, but the study was not randomised and the gap was gone at 12 months.

Beidelschies et al., JAMA Network Open, 2019

Ultra-processed food and overeating

In a tightly controlled ward study, people ate about 500 more calories a day and gained weight on an ultra-processed diet compared with an unprocessed one.

Hall et al., Cell Metabolism, 2019

Mediterranean-style eating and heart disease

A Mediterranean diet with extra olive oil or nuts reduced major cardiovascular events compared with a lower-fat control diet.

Estruch et al., New England Journal of Medicine, 2018 (PREDIMED, republished)

Honest about weak spots

  • Functional medicine as a field lacks randomised trial evidence; surgeon and blogger David Gorski (Science-Based Medicine, 2014; Respectful Insolence, 2019) argues its useful parts (diet, exercise, sleep) are not unique and its unique parts (broad testing, supplements, 'detox') are not proven.
  • A 2021 Red Pen Reviews analysis of Eat Fat, Get Thin scored its scientific accuracy 1.2 out of 4, finding the claim that saturated fat does not cause heart disease conflicts with most controlled studies.
  • Commercial ties are large: he co-founded and is chief medical officer of Function Health (direct-to-consumer lab testing) and sells supplements through his own online shop; nutrition scientist Adrian Chavez (Katie Couric Media, 2026) noted one of his supplement stacks supplies 7,000 IU of vitamin D a day, above the usual 4,000 IU upper limit.
  • On The Diary of a CEO podcast he said gluten can contribute to conditions including autism; a BBC World Service investigation (December 2024) reported this, and experts it consulted called the claim false.

Where experts disagree

  • Animal foods: Hyman includes grass-fed meat, eggs and fish in a mostly-plant diet; Michael Greger advises a whole-food, fully plant-based diet.
  • Protein: Hyman takes 30–50 g of protein in one shake and stresses high protein with age; Valter Longo advises about 0.8 g/kg a day for adults under 65.
  • Fat: Hyman argues saturated fat is not a main driver of heart disease; Michael Greger and most heart guidelines advise keeping saturated fat low.

Sources

Last reviewed October 2026. Spotted an error? Tell us at hello@lifelongmethod.com and we’ll correct it.

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