Prolon® with Dvora Citron, RN MS, NBC-HWC

Why I do Prolon

I have completed 38 rounds of Prolon® since my first in September 2019.

I first heard about it on Dr. Joel Kahn's Heart Doc VIP podcast. Dr. Kahn is an integrative cardiologist who eats a whole-food, plant-based diet. He shared that he has always tended toward the "zaftig" side, and that Prolon helps him keep his weight in check. He also understands the science behind the Fasting Mimicking Diet created by Dr. Valter Longo of the USC Longevity Institute.

I eat a very nutritious plant-based diet too. I also have a big appetite and a petite frame, and I have always worked to maintain a healthy weight. His experience convinced me to try it. I did my first round in September 2019.

I keep doing Prolon because I am committed to healthy aging, and a few times a year it gives me a structured reset that I can actually complete.

What is Prolon?

Prolon® is a five-day, plant-based meal program designed to mimic some effects of fasting while you still eat. It is food, not a drug. It was developed by Dr. Valter Longo from two decades of research at the USC Longevity Institute.

Everything you eat for the five days arrives in one box, with a smaller box for each day. Each day includes soups, a nut-based bar, snacks, herbal teas, and supplements.

The current version, Prolon® Next Gen, uses certified organic soups and teas made with ingredients sourced from farms in Italy. The soups are fully cooked, so you can eat them hot or cold.

What the five days feel like

• Day 1: This is the easiest day, with the most calories. Your body begins to shift.
• Days 2 and 3: Your stored glycogen drops, and many people move into ketosis. These are usually the hungriest days.
• Days 3 and 4: This is the window when research suggests the body's cellular clean-up process, called autophagy, is most active.
• Day 5: Energy often lifts on this day. You start preparing for a gentle transition day.
• Day 6: You return to normal eating, slowly. Light, plant-based meals work best.

What the research actually shows

The studies are promising, but they are small.

In a 2017 randomized trial, three monthly cycles reduced body weight, waist size, blood pressure, and markers of inflammation and blood sugar. The biggest improvements were in the people who started at higher risk.

A 2024 analysis found that three cycles were associated with a 2.5-year decrease in median biological age, independent of weight loss. It also found lower insulin resistance and less liver fat.

These are markers of health, not long-term outcomes like heart attacks or fractures. The research also comes from the lab of Prolon's founder. I find the evidence meaningful enough to use Prolon myself, and I think you deserve to know its limits.

Prolon is not a weight loss drug. It will not produce GLP-1 results on the scale. Its value is as a periodic reset a few times a year, not as a daily intervention.

What happens after Prolon?

The weeks between cycles are part of the program.

Day 6 is a transition day. Plan on light, plant-based meals, and don't treat it as a celebration.

After that, rebuild with enough protein and with strength training. This matters even more after 60, because Prolon is intentionally low in protein and you want the reset to cost you nothing in muscle.

Most people repeat Prolon a few times a year. Decide how often with your doctor.

A note for women 50+

Prolon does not build muscle or bone. It does appear gentle on muscle: in the original trial, three cycles caused no loss of lean body mass. That study did not measure strength, though, and there are no human studies on Prolon and bone.

What actually protects muscle and bone after 50 is progressive strength training, enough protein, and a conversation with your doctor about bone density and hormone therapy. Prolon can sit on top of that foundation, but it cannot replace it.