This lecture by Dr. Pradip Jamnadas, a cardiologist, addresses the controversial topic of fasting for survival by grounding it in human evolution and biochemistry. The core message is that modern eating patterns are inconsistent with human genetics, and fasting is a natural mechanism to promote health, longevity, and cellular repair.

The Evolutionary and Hormonal Rationale

Dr. Jamnadas argues that humans evolved over 2.5 million years to survive periods of fasting, a genetic blueprint that has not adapted to the constant availability of food today. He debunks common myths:
Myth of Constant Energy: The feeling of energy from eating sugar is a false “junkie” high, which stimulates the brain’s reward (dopamine) center.
Myth of Frequent Meals: The notion that one must eat five to six times a day, or that breakfast is the most important meal, is “totally false” and incongruent with human physiology.
The central hormonal factor is Insulin. High insulin levels (caused by frequent eating) lock up fat stores, making weight loss impossible and leading to Insulin Resistance and Type 2 Diabetes. Fasting is presented as the most potent way to drop insulin levels, thereby increasing the body’s sensitivity to it and unlocking fat to be used for fuel.

The Biochemistry of Fasting

The body undergoes a predictable shift in fuel sources during a fast:
0–12 Hours: The body uses up the readily available glycogen (stored glucose) in the liver and muscles.
12–24 Hours: Gluconeogenesis (the liver making new glucose from protein turnover) maintains stable blood sugar levels, preventing hypoglycemia.
18+ Hours (Ketosis): With insulin levels low, fat stores are broken down, and the liver converts fatty acids into ketones (Beta-Hydroxybutyrate). The brain, traditionally thought to be an obligate glucose utiliser, can utilise up to 70% of its energy from ketones after a 7-day fast, which is described as a “cleaner burn”.

Major Anti-Aging and Health Benefits

Fasting triggers multiple potent biological processes:
Autophagy (Cellular Repair): This process starts around 18 hours and maximises at three days. The body acts as a “reset switch,” recycling old, redundant, or damaged intracellular organelles and proteinaceous material (like those linked to Alzheimer’s) into new building blocks, essentially rejuvenating the cell.
Growth Hormone (HGH) Boost: A two-day fast can increase HGH production by 2,000% in men and 1,300% in women. HGH promotes muscle growth and is key to staying young.
Stem Cell Mobilisation: Refeeding after a significant fast (like a 3-day fast) triggers the bone marrow to release new stem cells to repair and replenish organs and tissues.
Increased Alertness: Fasting increases epinephrine and cortisol, boosting the metabolic rate and making a person more alert and focused.
Gene Expression: Fasting activates genes like FoxO3, which turns on the body’s natural antioxidant and DNA repair mechanisms.

Practical Fasting Recommendations

Dr. Jamnadas outlines different fasting durations for different goals:
Type of Fasting Duration/Frequency Goal
Time-Restricted Feeding (TRF) Daily 6–8 hour eating window (eat once or twice a day) General health maintenance, minor weight loss, and disease prevention
Weekly Fast 36 hours once a week Significant boost in immunity and fat burning
Therapeutic Water Fast 3, 5, or 7 days (water-only) Treat severe chronic conditions (cancer, autoimmune disease, Alzheimer’s) or significant weight loss

Important Precautions:

Diabetes Medication: Diabetics on insulin or sulfonylureas (like Glyburide) must consult a physician as these medications should be stopped or drastically reduced during a fast to prevent dangerous low blood sugar.
Electrolytes and Refeeding: During a fast, drink lots of water and use a pinch of salt (e.g., Himalayan salt) to prevent cramps and dizziness. Upon refeeding, use bone broth to avoid “refeeding syndrome” (deficiencies in phosphate, potassium, and magnesium).
Nutrition: Avoid processed foods and high-protein supplements, as too much protein (specifically IGF-1) activates the MTOR pathway, which increases cancer risk and turns off autophagy.