Intermittent fasting, the longevity diet & prolonged fasting — a deep dive

Longevity

By Dr Mavis Pak · August 2024 · 7 min read

Why dietary strategy matters for longevity

Of all the levers we can pull for health and longevity, what we eat — and when we eat — has among the most powerful and well-evidenced effects. Three approaches in particular have accumulated strong scientific support: intermittent fasting (IF), the Longevity Diet developed by Dr Valter Longo, and the prolonged fasting Fasting Mimicking Diet. Let me break each one down.

Intermittent fasting (IF)

Intermittent fasting is not a diet in the traditional sense — it's about when you eat, not what you eat. The most popular protocol is 16:8 (eating within an 8-hour window, fasting for 16 hours). The 5:2 approach — eating normally five days a week and restricting to around 500 calories on two non-consecutive days — is another well-studied option.

The mechanisms: fasting periods lower insulin levels, shift the body toward fat oxidation, activate autophagy (cellular self-cleaning), and reduce inflammatory markers. Multiple clinical trials confirm benefits for weight, metabolic health, and some markers of longevity.

The longevity diet (Dr Valter Longo)

Dr Valter Longo is one of the world's leading longevity researchers at USC. His Longevity Diet is broadly plant-based and pescatarian, low in protein (particularly animal protein) until age 65, rich in legumes, olive oil, nuts, and complex carbohydrates, and low in refined sugars and saturated fats. It draws on observations from Blue Zone populations and decades of laboratory research on ageing pathways.

The prolonged fasting fasting-mimicking diet

This is my personal favourite of the three — the most precisely engineered. prolonged fasting is a 5-day commercially available programme that provides specific ratios of macronutrients, micronutrients, and calories to keep the body in a fasting-like metabolic state while still providing nutrition. Developed by Dr Longo himself, it has been through human clinical trials.

Key clinical findings: prolonged fasting reduced visceral fat, improved insulin sensitivity, reduced C-reactive protein (inflammatory marker), and showed evidence of autophagy activation — all within five days. Many patients report feeling noticeably clearer and lighter by day four or five.

I have personal experience with prolonged fasting and recommend it to appropriate patients as a quarterly or monthly reset. It is not suitable for everyone — please consult a doctor before attempting it.

Which approach is right for you?

• If you want a daily sustainable protocol: start with 16:8 intermittent fasting
• If you want a long-term dietary philosophy: explore the Longevity Diet
• If you want a periodic metabolic reset: consider prolonged fasting under medical supervision
• Ideally, combine all three in a layered approach