Mike Israetel (sport physiologist (phd)) and Jason Fung (physician, kidney specialist) side by side: how they train, eat, supplement and sleep, how strong the evidence is, and how to build a plan from either or both.
Training splits are our estimates from each expert’s published routine. Following checked October 2026.
The key differences
Israetel puts more of the week into strength: about 65% against 45%.
Fung puts more of the week into aerobic base (zone 2): about 35% against 25%.
In plans in their style, Israetel's hard sessions are 1-minute intervals; Fung's are 4-minute intervals (Norwegian 4 × 4).
We rate the evidence behind Israetel's protocol higher: solid, against mostly weak for Fung.
Supplements that go into a plan: Israetel, none (food first); Fung, none (food first). Prescription items and personal stacks stay out of every plan.
Neither has a separate mobility routine; plans add 10 minutes a day of basics.
Protocols side by side
Each line is rated for the evidence behind it. “Doctor only” items never go into a plan.
Training
Mike Israetel
For the average person, about 30 minutes of training twice a week gives the best return on time.Some evidence
After 40: most sets in the 10–20 rep range, some at 20–30, and 5–10 reps only rarely, because heavy low-rep sets raise the risk of injury.Some evidence
Train each muscle twice a week, starting with 1–2 hard sets per muscle per session, and add a set the next week if you recovered well.Some evidence
Lower the weight slowly and pause for 1–2 seconds at the bottom.Some evidence
Warm up more: three warm-up sets (light, medium, heavier) before the first working set, and 1–2 before each later exercise.Personal habit
Add weight in small steps: rarely more than about 2.5 kg or one rep per set at a time.Personal habit
Choose joint-friendly exercises with a high stimulus, for example a hack squat instead of a heavy back squat.Some evidence
Take a planned easy week every 4–6 weeks, and a lower-volume month about every 5 months.Personal habit
Jason Fung
No specific guidance in what we reviewed.
Eating
Mike Israetel
If you want to gain muscle, only gain weight when you are lean: about 0.25 kg a week for 4–8 weeks, then a fat-loss phase.Personal habit
Stay under about 20% body fat while gaining, come back to about 15% afterwards, and get blood tests after gaining phases.Personal habit
Jason Fung
Cut added sugar and refined grains; eat whole foods with natural fats.Some evidence
Stop snacking: three meals a day, then skip one meal a day.Personal habit
Eat within a shorter window of the day (time-restricted eating).Some evidence
Fasts of 24 hours (skipping two meals in a row) two or three times a week, as used in his clinic's programme.Personal habit
Longer fasts of several days; in 2016 he said fasts of up to a month were fine.Doctor only
For type 2 diabetes: no sugary drinks, fructose or processed food, and more natural fats.Doctor only
Weak spots to know
Mike Israetel
Most of his content is aimed at bodybuilders and younger lifters; advice for people over 40 is a smaller part of it.
Many specific numbers, such as when to take easy weeks or how fast to add sets, are coaching rules of thumb rather than findings from trials.
He sells training programmes and diet products through RP, the company he co-founded.
Jason Fung
Red Pen Reviews scored The Obesity Code at 31% for scientific accuracy, and The Diabetes Code at 33%.
His central claim that calories do not matter is contradicted by controlled studies.
Much of his support comes from case reports, small older studies and his own clinic.
Build a plan from Israetel, Fung or both
Your free plan shows a week of gym sessions, cardio, a day of eating, supplements and mobility, fitted to your age, time and health.
What is the main difference between Mike Israetel and Jason Fung?
Their training split differs most in strength: Israetel about 65%, Fung about 45% (our estimate from their published routines). Israetel's signature habit is 2 × 30 min, close to failure; Fung's is Fasting, less sugar.
How much protein do Israetel and Fung recommend?
Israetel: No fixed target. Fung: No fixed target.
Whose advice has stronger evidence?
We rate the evidence behind Israetel's protocol higher: solid, against mostly weak for Fung.
Do Israetel and Fung disagree?
Not directly in what we reviewed. Their differences are in emphasis: israetel puts more of the week into strength: about 65% against 45%.
Can I combine Israetel and Fung?
Yes. In Build my mix you choose one expert per area, for example one for strength and another for eating. Your free plan shows the result straight away.