What Is The Obesity Code? Insulin, 16:8 Fasting, and Snacking
The Obesity Code by Dr. Jason Fung: insulin resistance, time-restricted eating (16:8), eliminating snacking, and pairing fasting with protein and lifting.
Insulin, snacking, and time-restricted eating — Jason Fung without unsupervised hero fasts
The Obesity Code made intermittent fasting sound like endocrinology instead of willpower. The keepers are fewer snacks, fewer liquid sugars, and a daily eating window. The danger is fasting on glucose-lowering drugs without a clinician. This guide places Fung next to Longo and modern IF practice.
Frequency
Daily eating window
Duration
4–12 weeks as an experiment
Level
Intermediate

Key Takeaways
- 1Constant grazing keeps insulin busy; a defined eating window is the first experiment
- 2Calories still exist — Fung oversells ‘hormones only’
- 316:8 is enough for most; multi-day fasts are optional and riskier
- 4Diabetes meds, pregnancy, and eating-disorder history are stop signs
Who this is for
- ·Snackers who need a why
- ·Readers comparing Fung vs Longo vs Means
- ·Anyone about to try OMAD in week one
The Insulin Story
Moderate EvidenceFung’s core claim: obesity is hormonally defended, and frequent refined carbohydrate keeps insulin (and hunger) high. That is a useful correction to ‘eat less, move more’ as the only sentence.
It is not a reason to pretend energy balance vanished. People who fast and then eat pizza every night are running a different protocol than the book describes.
A Sane Window
Moderate EvidenceStart with 12:12, then 14:10 or 16:8. Eat protein and plants in the window. Black coffee is fine; ‘fasting’ cream lattes are a loophole.
Longo’s fasting-mimicking diet is the periodic alternative if daily restriction wrecks your training or sleep. See our Longevity Diet guide.
Safety
Strong EvidenceInsulin, sulfonylureas, SGLT2s, and pregnancy change the risk math. So does a history of bingeing. This is a book club, not a clinic.
As an Amazon Associate, Reo Tuku Iho Limited earns from qualifying purchases through Amazon links on this site. Full disclosure
Sources
Key references cited in this guide. Links open the original publication or abstract.
- Metabolic effects of intermittent fastingAnnu Rev Nutr, 2017
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Read guideLast updated: 2026-09-21 · For informational purposes only. Not medical advice. Consult a healthcare provider before starting any new health protocol. Health disclaimer.