#59 - Jason Fung, M.D.: Fasting as a potent antidote to obesity, insulin resistance, type 2 diabetes, and the many symptoms of metabolic illness
Jason Fung, nephrologist and best-selling author, discusses individualized fasting for metabolic disease, arguing hyperinsulinemia is the root problem. He also critiques evidence-based medicine and compares scientific disciplines.
Deep Dive Analysis
19 Topic Outline
Introduction to Dr. Jason Fung and his clinical approach
Comparing scientific disciplines: Medicine and Biology versus Physics
Limitations of evidence-based medicine in chronic disease
Nephrology's unique insights into early metabolic disease
Challenging the conventional insulin resistance paradigm
The overflow paradigm: Hyperinsulinemia as the root problem
Why common type 2 diabetes treatments make things worse
SGLT2 inhibitors: A new approach to glucose management
Hyperinsulinemia drives the entire metabolic syndrome
Type 2 diabetes and obesity as protective mechanisms
Causality: Hyperinsulinemia driving adiposity
Role of inflammation and other hormones in metabolic health
Chronic diseases as 'diseases of too much growth'
Manipulating nutrient sensors (insulin, mTOR, AMPK) to reduce proliferation
Fasting and dietary restriction in clinical practice
Case study: Reversing diabetic foot ulcers with fasting
Managing common challenges during fasting (sleep, electrolytes, muscle loss)
Fasting for healthy individuals and longevity
Fasting and gallstone risk
6 Key Concepts
Insulin Resistance (Conventional View)
The traditional understanding that cells become 'resistant' to insulin, meaning insulin cannot effectively open the 'gate' to allow glucose into the cell, leading to high blood glucose despite normal or high insulin levels.
Hyperinsulinemia (Overflow Paradigm)
An alternative model suggesting that cells are not resistant to insulin's signal, but rather are already too full of glucose and fat. High insulin levels are a response to this cellular overflow, attempting to force more glucose in or clear it from the blood.
Selective Insulin Resistance
A paradox observed in conventional insulin resistance, where insulin's glucose-lowering effect is impaired, but its other effects, such as stimulating fat production (de novo lipogenesis) or promoting growth, remain sensitive or even heightened within the same tissues.
Evidence-Based Medicine (Critique)
A framework for medical decision-making that, while valuable, is seen as primarily a search for consensus rather than truth. This can lead to slow adoption of new, effective theories or treatments if they lack extensive, long-term randomized controlled trials, even if clinical observations suggest benefit.
Diseases of Too Much Growth
A conceptual framework proposing that many chronic diseases prevalent today, including obesity, type 2 diabetes, cardiovascular disease, and cancer, are fundamentally characterized by excessive cellular proliferation and growth, often driven by overactive nutrient sensing pathways.
Medical Bariatrics
A term used to describe the therapeutic application of fasting to achieve metabolic improvements similar to those seen with bariatric surgery, particularly in reversing type 2 diabetes, by effectively reducing hyperinsulinemia and clearing excess fat from internal organs.
14 Questions Answered
The conventional 'lock and key' paradigm fails to explain the central paradox where insulin's glucose-lowering effect is impaired, but its other effects, like fat creation (de novo lipogenesis) and growth, remain highly active in the same tissues.
It's better understood as an 'overflow problem' or hyperinsulinemia, where cells are already too full of glucose and fat, preventing more glucose from entering, leading to the body producing even more insulin in an attempt to clear the blood glucose.
Many traditional drugs for type 2 diabetes, such as sulfonylureas and exogenous insulin, increase insulin levels, which, under the overflow paradigm, further fills already overloaded cells, masking the problem and making the underlying disease progress.
Unlike older drugs that increase insulin, SGLT2 inhibitors work by making the kidneys excrete excess glucose in the urine, effectively 'emptying the sugar bowl' from the body, leading to significant organ protection despite modest blood sugar lowering.
Hyperinsulinemia drives abdominal obesity (liver exporting fat), high triglycerides (excess fat production), low HDL (linked to high triglycerides), and high blood pressure (insulin causes sodium reabsorption), linking all components of metabolic syndrome to a single underlying issue.
Yes, these conditions can be viewed as the body's protective responses against excessive glucose and insulin; for example, fat storage (obesity) sequesters excess energy, and insulin resistance prevents further glucose overload in cells, and glycosuria (peeing out sugar) is the body's attempt to excrete excess glucose.
Experimental evidence, such as patients gaining weight when given insulin and losing weight when insulin is reduced, strongly suggests that hyperinsulinemia is a causal driver of obesity, rather than obesity solely causing hyperinsulinemia.
Many chronic diseases are seen as 'diseases of too much growth,' where excessive cellular proliferation, often stimulated by growth factors like insulin and mTOR, contributes to conditions like atherosclerosis (smooth muscle proliferation) and cancer.
Time-restricted feeding limits the daily eating window (e.g., 16-8 hours), while intermittent fasting involves periodic, longer periods of complete or significant caloric reduction (e.g., 24-hour fasts several times a week, or multi-day fasts).
In some severe cases, patients on large doses of insulin for many years have been able to get off all their insulin and reverse type 2 diabetes within 5 to 18 days of starting aggressive fasting protocols.
Patients often experience hunger, headaches, cramps, and difficulty sleeping due to sympathetic nervous system activation, but these symptoms are usually temporary and manageable with proper preparation and electrolyte management.
In overweight or obese individuals, the body primarily burns stored fat for energy during fasting, and while some protein breakdown occurs (gluconeogenesis, autophagy), it's often from superfluous connective tissue and skin, with minimal clinically significant muscle loss.
Yes, periodic fasting can be beneficial for healthy individuals by regularly lowering insulin levels, which helps prevent diseases of hyperinsulinemia such as heart disease, stroke, cancer, Alzheimer's, type 2 diabetes, and obesity.
While some weak epidemiology suggests a link, Dr. Fung believes that low-fat diets, by reducing bile flow, are a more likely cause of gallstone formation, and that fasting itself is not a significant clinical problem for gallstones.
16 Actionable Insights
1. Understand Hyperinsulinemia as Root Cause
Recognize that metabolic syndrome and type 2 diabetes stem from cells being ’too full’ of glucose and fat (an overflow problem) due to chronically high insulin (hyperinsulinemia), rather than cells being unable to absorb glucose. This shifts the focus from ‘insulin resistance’ to ‘hyperinsulinemia’ as the underlying problem.
2. Prioritize Lowering Insulin
To address hyperinsulinemia and its associated diseases, the primary treatment strategy should be to lower insulin levels and reduce overall body glucose, rather than increasing insulin or forcing glucose into already full cells.
3. Utilize Fasting to Lower Insulin
Implement fasting as the most potent method to significantly lower insulin levels and force the body to utilize stored fuel, thereby emptying excess glucose and fat from cells.
4. Consider Aggressive Therapeutic Fasting for Severe Conditions
For severe metabolic diseases like non-healing diabetic foot ulcers, consider medically supervised, aggressive fasting protocols (e.g., a seven-day water fast followed by 36-hour fasts three times a week) to rapidly reverse the condition.
5. Individualize Fasting Protocols
Tailor fasting regimens to individual needs, considering the severity of the condition, age, urgency, and personal willingness, rather than adhering to a one-size-fits-all approach.
6. Prioritize Safety During Fasting
Always stop fasting immediately if you feel unwell, and then seek medical advice, as safety is paramount and regimens can be adjusted or alternative strategies pursued.
7. Cultivate Supportive Fasting Environment
Recognize that the psychological challenges of fasting are often greater than the physical ones; actively create a supportive environment and community to aid in adherence and success.
8. Start with Time-Restricted Eating
Begin by restricting your eating window (e.g., between 12 pm and 8 pm) to reduce eating frequency and break the habit of constant consumption, which can help lower insulin and improve metabolic health.
9. Manage Fasting Sleep Issues
Expect potential sleep difficulties during fasting due to sympathetic nervous system activation; acknowledge it as temporary and consider using supplements like phosphatidylserine and GABA (if available over-the-counter) to aid sleep.
10. Supplement Magnesium, Use Bone Broth
Supplement magnesium, especially if you are a type 2 diabetic, to prevent cramps. If experiencing dizziness or other issues during fasting, consider consuming bone broth with salt to replenish electrolytes and feel better.
11. Periodic Fasting for Longevity
For healthy individuals, engage in periodic fasting (e.g., 14-hour daily fasts, occasional longer fasts) to regularly lower insulin levels, which can reduce the risk of chronic diseases linked to hyperinsulinemia (e.g., heart disease, cancer, Alzheimer’s, type 2 diabetes, obesity).
12. Question Risks of Inaction
When considering new treatments, always evaluate the risk of not doing something (e.g., continuing conventional treatments that lead to worsening conditions) against the risk of trying a new, potentially beneficial intervention.
13. Monitor Kidney Health Markers
For longevity and early detection of vascular damage, regularly monitor kidney function indicators such as cystatin C creatinine and microalbumin (urinary albumin excretion).
14. Avoid Very Low-Fat Diets
Avoid very low-fat diets, as they can lead to bile sludge and gallstone formation by reducing the necessary flow of bile; ensure adequate fat intake to stimulate proper gallbladder function.
15. Embrace Clinical Flexibility
Avoid rigid, dogmatic approaches in treatment; be prepared to adjust strategies based on individual patient responses, as clinical practice often proves theoretical assumptions wrong.
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7 Key Quotes
If your theory doesn't work, then it's not a good theory. And this is what they say in physics, which they don't say in medicine.
Jason Fung
Evidence-based medicine is not a search for truth, it's a search for consensus.
Jason Fung
The risk of doing something is usually more in our forefront. It's that risk of not doing something that people often forget.
Peter Attia
The problem is not insulin resistance per se. The problem is hyperinsulinemia.
Jason Fung
If you have a patient who 10 years ago was on one drug and now they're on huge doses of insulin, that diabetes never got better. The sugars might've gotten better, right? But the actual disease itself of type 2 diabetes never got better. It only got worse.
Jason Fung
Fasting is what I call medical bariatrics. You get all the benefits of bariatric surgery without doing any surgery.
Jason Fung
It's like storing firewood for the winter. And then as soon as you need to use it, you chop up your sofa and throw it in the fire. Like who would do that? But we think that our bodies are just that stupid.
Jason Fung
1 Protocols
Aggressive Fasting Protocol for Severe Diabetic Foot Ulcer
Jason Fung- Initiate with a 7-day water-only fast (patient was in hospital, on clear fluids, no sugar).
- Transition to 36-hour fasts, three times a week.
- Monitor blood sugars and overall well-being very closely.
- Adjust regimen or stop fast if patient does not feel well.
- Provide psychological support and warn of potential side effects like hunger, headaches, and sleep issues.
- Ensure a supportive environment from family and medical team.