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A scientifically designed protocol
Are you losing the wrong kind of weight?
Most diets can't tell the difference between fat and muscle. Your body can. The Prolon 5-Day Fasting Mimicking Diet is clinically formulated to help you lose the fat you don't want and protect the muscle you do.
Start your reset
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★★★★★
4.4 Stars
47 Clinical Trials
1M+ Happy Customers
Stanford
· Mayo Clinic · Harvard
20K+
physicians
25+
years of research
Patented
formulation
Head to head · published clinical study
Prolon vs. the gold-standard Mediterranean diet, over 120 days
Mediterranean diet
Lost weight. Maintained muscle.
✕ Considered the gold standard for cardiometabolic health
✕ Delivered cardiometabolic benefits
✕ Helps maintain muscle mass
✕ Months of dietary change required
Prolon 5-Day FMD
Lost the fat. Kept the muscle.
Matched the Mediterranean diet's cardiometabolic benefits
Protected more muscle than the Mediterranean diet in the study
5.7 lbs lost and 1.6 inches off the waist across 3 cycles
Five days at a time, not months of restriction
7 reasons it works
Why the weight comes off and stays off
What you lose matters more than how much you lose
Most diets can't tell the difference between fat and muscle. They just drop the number on the scale. Prolon is formulated to know the difference, targeting stored fat for fuel while preserving the lean muscle mass that supports your metabolism, immunity, and longevity.
The weight you lose is the weight you wanted to lose.
5.7 lbs lost · 1.6 inches off the waist · published clinical results across 3 cycles
Five days at a time, not months of dieting
Most weight-loss approaches ask for forever — daily counting, weekly weigh-ins, restriction that drags on. The Prolon protocol runs five days at a time, then you go back to eating the way you normally eat.
Those published clinical results, 5.7 lbs lost and 1.6 inches off the waist, came from three cycles. Most customers run three to four cycles per year. Five days a few times beats five months once. The takeaway:
the body responds to it like water, not like a meal.
You can eat while you lose
Water fasts, juice cleanses, and extreme calorie cuts work against your body. Prolon is different: plant-based soups, nut bars, olives, kale crackers, and herbal teas, precisely formulated to keep your cells in a fasting state while you stay nourished.
Precision nutrition, not deprivation.
The cellular work that makes the loss real
By day three, your cells enter autophagy: damaged cellular components clear out, making way for healthier, younger functioning cells. Prolon is the only nutrition program clinically proven to trigger autophagy in humans.
For weight loss, that means the body isn't just dropping water and muscle. It's resetting metabolism from the inside out.
The only nutrition program clinically proven to trigger autophagy in humans
Younger biological age, on top of pounds lost
In published clinical research, participants saw measurable shifts in biological-age markers after completing three monthly cycles of the 5-Day program. So the weight you lose isn't the only thing that changes. What's happening inside does too.
The compound effect: a feeling of being lighter and younger, at the same time.
Published clinical results · biological-age markers shifted younger
No drugs. No injections. No extreme diets.
If you've looked at GLP-1s, tried crash diets, or worked through a shelf of supplements, the message has always been the same: force your body into results. Prolon takes the opposite approach. It works with your body's own fasting response.
Five days a few times a year, no prescriptions, no side-effect list to memorize, no plateau roulette.
25 years of research from USC, not a wellness trend
Prolon was developed by Dr. Valter Longo at the USC Longevity Institute. 25+ years of clinical research, 47+ clinical trials, 18 research institutions including Stanford and Mayo Clinic, 200+ patents, and a network of more than 20,000 physicians.
It's the only nutrition program patented for longevity support through cellular rejuvenation.
From a customer
★★★★★
"I can't believe I went down 9.9 pounds in five days and lost two inches off my waist."
Whitney
Verified Prolon customer · shared on social
Individual results vary. Whitney's experience reflects her own use of the 5-day protocol and is not a guaranteed outcome.
The 5-day arc
How the body shifts, day by day
Day 1
Body adjusts to lower glucose
Day 2
Stored fat starts mobilizing, ketones rise
Day 3
Autophagy activates, cellular cleanup begins
Day 4
Fat-burning state in full swing
Day 5
Cellular renewal continues into days six and seven
★★★★★
4.4 Stars
1M+ Happy Customers
Prolon 5-Day Fasting Mimicking Diet
A five-day program clinically formulated to target fat, protect muscle, and reset your body from the inside.
Designed to target fat and protect lean muscle mass
The only nutrition program shown to trigger autophagy in humans
No drugs, no injections, no long-term food deprivation
Plant-based: soups, nut bars, olives, kale crackers, herbal teas
HSA/FSA eligible · 90-day money-back guarantee
$182.75
$215.00
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Original 5-Day FMD shown. Next Gen (ready-to-eat) available from $255.
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HSA/FSA
eligible
90-day
money-back guarantee
1M+
happy customers
Most customers run three to four cycles per year. Individual results vary.
The 5-day arc
Questions
What people ask before their first program
How much weight will I lose?
Individual results vary. In published clinical research, participants saw an average of 5.7 lbs of weight loss and 1.6 inches off the waist across 3 cycles, with muscle mass preserved. Most customers follow three to four cycles per year for compounding results.
Will I be starving?
You eat every day of the five-day program: plant-based soups, nut bars, olives, kale crackers, and herbal teas, precisely formulated to keep your cells in a fasting state while you stay nourished. Some people do feel hungry at points, especially on the first cycle, and that's normal. Most find it more manageable than they expected, and it tends to get easier with each cycle.
Will the weight come back?
What you do after the program matters. In published research, the majority of the weight loss stayed off even after participants returned to normal eating. Combined with balanced eating and a healthy lifestyle between cycles, the 5-Day program is built for sustained results, not a yo-yo. Most people repeat it three to four times a year.
Is it safe?
The 5-Day Fasting Mimicking Diet has been tested in 47+ clinical trials and is trusted by more than 20,000 physicians. As with any nutrition program, talk to a clinician about decisions specific to your care.
What's the guarantee?
90-day money-back guarantee, no questions asked. HSA/FSA eligible.
Five days. Real change.
Lose the fat. Keep the muscle. Reset the body, from the inside out. The protocol that 20,000+ physicians trust.
Start your RESET
Subscribe & Save 15% · HSA/FSA eligible · 90-day money-back guarantee
© Prolon · L-Nutra. Patented fasting mimicking technology developed with the USC Longevity Institute.
These statements have not been evaluated by the FDA. Not intended to diagnose, treat, cure, or prevent any disease.