Prolon’s fasting-mimicking diet

Real trials; early evidence.

Prolon sells a five-day boxed plant-based meal plan, low in calories, sugar and protein, built on research from Valter Longo’s lab. Short answer: in a randomized trial, three monthly cycles lowered weight, body fat, blood pressure and IGF-1 compared with eating normally, and an open-label trial in Crohn’s disease found more people improved. Both were unblinded and compared with no change in diet, and the developers are tied to the company. They measured markers, not lifespan.

How the evidence flows

Each claim (middle), the studies that tested it (left) — green found it, red found nothing — and the grade they add up to (right). Drawn from the same records as the grades below. Tap to open full size.

Fasting-mimicking diet (Prolon) · evidence checked 2026-10-28

What the research shows

Grades are calculated from the studies listed, by fixed rules.

Monthly 5-day fasting-mimicking diets improve risk markers for aging and diseaseEarly evidence
In one randomized trial, three monthly cycles lowered weight, body fat, blood pressure and IGF-1 compared with eating normally; a later analysis of the same blood samples reported a lower “biological age” score. Neither was blinded or named one main outcome, the comparison was no diet change at all, and the later analysis lists company ties. Markers, not disease or lifespan, were measured.
- Open-label randomized trial, 100 people, 13 weeks (2017) — secondary outcome: improved. Funder not checked.
- Open-label randomized trial, size not stated (2024) — secondary outcome: improved. Funded by mixed sources.
A fasting-mimicking diet helps mild-to-moderate Crohn’s diseaseEarly evidence
One open-label trial found more people responded on monthly 5-day cycles than on their usual diet. Promising, unblinded, and not a replacement for treatment — talk to your gastroenterologist first.
- Open-label randomized trial, 97 people, 13 weeks (2026) — primary outcome: improved. Funder not checked.
Prolon is “built on 25+ years of research” and “completed by over 1 million users”No real evidence
The ad said
“Five days of food. Twenty-five years of homework. / Built on 25+ years of research from Dr. Valter Longo’s lab at the USC Longevity Institute. / Completed by over 1 million users.”
Prolon · Facebook ad, seen Oct 2026
The human trials above are real but short and unblinded, and the diet’s developers are tied to the company; a million customers is a sales figure, not a result.

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