The only nutrition program clinically proven to trigger autophagy in humans
4.4 Stars
1M+ Happy Customers
A protocol That supports what changes after 40
Why belly fat shows up after 40 — and why dieting harder can make it worse.
Shifting estrogen and a slower metabolism can change where your body stores fat and how easily it holds on to muscle. Most diets can't tell the difference between the two, and after 40 that difference matters more than it ever has. The Prolon 5-Day Fasting Mimicking Diet (FMD) is clinically formulated to target stored fat while protecting the lean muscle you already work hard to keep.
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40+
Clinical trials
conducted with world-leading institutions
20k+
Physicians
recommending Prolon to their patients
130+
Issued patents
for optimizing longevity and healthspan
$48M
In scientific research
confronting the four major causes of mortality
Researched with
18
Research institutions
25+
Years of research
Head to head · published clinical study
Prolon 5-Day vs. the gold-standard Mediterranean diet, over 120 days
Two approaches, one randomized trial. One asked for four months of daily dietary change. The other asked for five days at a time.
Mediterranean diet
Lost weight. Asked for four months.
- —Considered the gold standard for cardiometabolic health
- —Delivered cardiometabolic benefits over 120 days
- —Helps protect muscle as part of a whole eating pattern
- —Months of daily dietary change required, every meal, every week
Prolon 5-Day FMD
Lost the fat. Protected the muscle.
- ✓20 days of Prolon was as effective as 120 days of the Mediterranean diet on heart health markers
- ✓Protected more muscle than the Mediterranean diet in the study, which matters more at a stage when lean mass is already harder to hold on to
- ✓Clinically proven average of 5.7 lbs lost and 1.5 inches off the waist after three consecutive monthly cycles
- ✓Five days at a time, without months of deprivation
Mishra A, Fanti M, Ge X, et al. Fasting mimicking diet cycles versus a Mediterranean diet and cardiometabolic risk in overweight and obese hypertensive subjects: a randomized clinical trial. npj Metabolic Health and Disease, 2023. Weight and waist results: Wei M, Brandhorst S, et al. Science Translational Medicine, 2017. Individual results vary.
Five days. A real change, inside and out.
Lose the fat. Protect the muscle. Give your body a reset built on 25 years of research and trusted by more than 20,000 physicians.
Subscribe and save 15% · HSA/FSA eligible
7 reasons it works
Why this works when the rules have changed
You did not stop trying; your biology changed the terms. Here is what a protocol that supports for this stage actually does differently.
01
What you lose matters more than how much you lose
Lean muscle gets harder to hold on to with age, and after 40 that decline can speed up quietly in the background. Most diets can't tell the difference between fat and muscle; they simply move the number on the scale. And some of what leaves is the muscle that supports your metabolism, your strength, and how you feel in your own body.
Prolon is formulated to know the difference: it targets stored fat for fuel while protecting lean muscle mass. So the weight you lose is the weight you want to lose.
Clinically proven average of 5.7 lbs lost and 1.5 inches off the waist after three consecutive monthly cycles
02
Five days, not months of deprivation
Most approaches ask for forever. Daily counting, weekly weigh-ins, a running commentary in your head at every family dinner. Between work, a household, and everyone who needs something from you, dieting becomes a way of life.
Prolon runs five days at a time, then you go back to eating the way you normally eat. The protocol behind the research is three monthly cycles to start, and then three to four times a year. Five days a few times a year beats five months once.
03
You keep eating
Plant-based soups, nut bars, olives, kale crackers, herbal teas. Every item is precisely formulated to keep your body in a fasting state while still providing nourishment. This is the opposite of the water fasts, juice cleanses, and cut-out-everything plans you are already tired of; with Prolon, you get the benefits of fasting, while you eat.
This is precision nutrition, not punishment.
04
The cellular work that makes the loss real
Around 72 hours into a prolonged fast, autophagy kicks in. This is the body's natural process of intracellular clean-up, where worn-out cellular components are cleared or recycled, making way for younger, more efficient versions of themselves. Prolon 5-Day is the only nutrition program clinically proven to trigger autophagy in humans.
This is the part you can't see on a scale, but is happening deep within your cells.
The only nutrition program clinically proven to trigger autophagy in humans
05
The other number that moves (biological age)
In published clinical research, three consecutive monthly cycles of the 5-Day program were shown to reduce biological age score by an average of 2.5 years - a figure based on markers in your blood, not the one on your driver's license. It's the number that describes how young or old your body is actually functioning.
This is the part people tell us they notice: lighter and, somehow, more like themselves again.
Biological age score reduced by an average of 2.5 years after three consecutive monthly cycles
06
No injections.
No prescriptions.
Weight-loss injections and medications often work by acting on the signals that tell you when you are hungry, and they only work as long as you keep taking them.
Prolon works the other way around. It uses food to put your body into a fasting state and lets your own biology take it from there, with results shown to last after return to normal eating. Five days, a few times a year - no shots, no prescriptions.
07
25 years of research from USC, not a wellness trend
The 5-Day FMD was developed by Dr. Valter Longo at the USC Longevity Institute, and touts 25 years of research, 40+ clinical trials, 18 research partners including Stanford and Mayo Clinic, 130 global patents, and a network of more than 20,000 physicians.
It is the only nutrition program patented for longevity through cellular rejuvenation and proven to trigger autophagy in humans. This is what evidence looks like.
Real results
★★★★★
"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 five-day arc
How your body resets, day by day
Five days is short enough to plan around, and long enough to reset your body.
Energy and clarity are user-reported experiences and vary from person to person.
Cellular renewal
Skincare that no serum can touch
The renewal that starts around Day 3 does not stay hidden inside your cells. It shows up in the one place you see every morning: your skin.
In a randomized controlled trial, three consecutive monthly cycles of the 5-Day program improved fine lines, skin tone and texture, and increased skin hydration by 25%, while enhancing overall radiance and clarity and evening skin tone. Users also report smoother, clearer skin and more confidence in how their skin looks.
25%
More hydration
Fine lines
Improved
Tone
Clearer and more even
All results measured after three consecutive monthly cycles of Prolon 5-Day. Maloh J, Wei M, Hsu WC, et al. Journal of Clinical Medicine, 2023. Individual results vary.
Start your reset
Five days, delivered to your door
One box, portioned by day. Nothing to plan, weigh or prep, and you choose the flavors.
Your order includes
- ✓Prolon 5-Day kit: soups, nut bars, snacks and teas, boxed by day
- ✓Free Welcome Kit with a Prolon water bottle, subscribers only
- ✓Free Getting Started guide, so Day 1 needs no research
- ✓15% off with a subscription, pause, skip or cancel anytime
4.4 rating · 1M+ programs completed
Prolon 5-Day FMD
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The same science-backed fasting benefits in 100% organic, pre-cooked soups. Open, warm, eat.
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One cycle is five days, most customers run three to four a year.
Prolon 5-Day
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Questions
What women ask before their first cycle
Prolon is designed to target fat and protect muscle, which is exactly what many women struggle with during perimenopause and menopause. There's skin research too — in a randomized trial of 45 women aged 35 to 60, three monthly cycles were associated with an increase in skin hydration. Many users also report more energy and mental clarity by the later days of a cycle.
Prolon is designed to target fat, not muscle. In published research, it shows muscle protection along with visceral fat loss. Unlike ordinary dieting, multiple cycles of Prolon help protect lean muscle mass alongside the weight you lose.
Prolon is a plant-based food program, not a medication, and more than 20,000 physicians, including women's health experts, recommend it. It is intended to be used in healthy adults; if you have a medical condition or are taking any medications, talk to your doctor before starting.
Many users lose up to 5 lbs in a single cycle, with clinical results showing an average of 5.7 lbs lost and 1.5 inches off the waist after three consecutive monthly cycles. That is the protocol we recommend starting with: three cycles over three months, then three to four cycles a year. Prolon targets visceral fat, the kind stored around the middle, which is also the kind that becomes more stubborn after 40. Individual results vary.
Prolon is HSA and FSA eligible, and subscriptions can be paused, skipped or cancelled at any time.
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.
Individual results vary. Clinical results referenced on this page were measured after three consecutive monthly cycles of Prolon 5-Day. If you are on hormone therapy or any prescription medication, or are managing a health condition, consult your doctor before starting.