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Short Summary
Main recommendation: Dietary change, including intermittent fasting variations such as the fasting mimicking diet and the 5:2 diet, can reverse or put type 2 diabetes into remission, and fasting should be considered by people with type 2 diabetes, those at risk, or those wanting to get ahead of it. Dr. Jason Fung argues that diet should be the first treatment step, and that fasting variations can be added to current medications to potentially reduce the need for them.
Key Points
- According to Dr. Fung, the ADA's long-standing view from the 1980s to 2020 that type 2 diabetes is chronic and progressive was a lie, since weight loss often improves or resolves it, and it wasn't until 2021 that ADA experts said it could be reversed.
- Lifestyle and diet change is the universally acknowledged first step in treating type 2 diabetes, but it is often ignored in clinical practice because diets are hard to sustain.
- Intermittent fasting is easier to sustain than permanent food-group elimination, and a time-limited treatment is easier for people to accept, comparable to a defined chemotherapy course.
- Fasting-based dietary treatment can be added to existing drug treatment and may reduce medication needs.
- Dr. Fung states that across the cited randomized controlled trials, fasting variations produced better blood sugar control and frequent medication reduction or drug-free remission compared with control groups.
Details Worth Noting
- Concrete instructions: The fasting mimicking diet is a pre-designed program of meals low in calories, sugar, and protein, and high in fats and complex carbohydrates, taken for five days each month. In the FIT study, day one was about 1,100 calories and days two to five about 750 calories each.
- Concrete instructions: The 5:2 approach eats normally five days a week and limits two days to about 500 to 600 calories. The JAMA study used meal replacement bars emphasizing medium-chain fatty acids and omega-3s to make the plan easier to follow.
- Concrete instructions: The InterFast-2 trial used three days a week at about 25% of usual calories, roughly 500 to 750 calories.
- Concrete instructions: A 2023 trial alternated five days of fasting at 840 calories with ten days of the regular diet, in 15-day cycles.
- FIT study (12 months): medication dosage was decreased in 40% of the fasting mimicking group versus 5% of controls, medications were stopped completely in 16%, and the fasting group lost an extra 3.6 kg, 2.2% body fat, and 3.5 cm waist circumference versus controls.
- JAMA 5:2 study: about 80% of participants reached remission (A1C below 6.5 without medications), and the fasting strategy reduced A1C more than the drugs metformin and empagliflozin.
- InterFast-2: A1C dropped 2.8% versus controls, weight fell 8% versus 4% in controls, and three of four fasting participants reduced insulin doses compared with fewer than 10% of controls.
- The 2023 trial found 44% drug-free remission at 12 months in the fasting group versus zero in controls, with participants averaging 1.86 medications at baseline.
Bottom Line
Dr. Fung presents fasting variations as a strong, evidence-backed dietary tool for type 2 diabetes, based on trial results he cites rather than independent verification of each study.
