K1 ketones by Prüvit are now available in the United States and Canada. They combine BHB (beta-hydroxybutyrate) with C5 ketones, a formula that goes beyond standard exogenous ketones to deliver what I describe in my practice as cleaner, more sustained metabolic energy without the crash.  Dr. Monica Mogne, ND | FastingON

K1 Ketones by Prüvit: The C5 Formula That Changes How Fasting Feels

buy k1 ketones

K1 Ketones Are Here!
Dr. Monica Mogne’s Clinical Recommendation

Most exogenous ketone products on the market today are built around the same molecule: BHB, or beta-hydroxybutyrate. BHB works. I’ve recommended it for years. But after studying the K1 formula and testing it alongside my clinical protocols at FastingON, I can tell you there’s something meaningfully different happening here.

K1 introduces C5 ketones, a distinct ketone substrate that the body metabolizes through a different pathway than BHB. In practice, what that means for my patients is a ketone experience that feels less like a spike and more like a steady floor of energy,  exactly what you want when fasting for 16, 18, or 20 hours.

K1 is now available to purchase in the US and Canada. Europe opens April 28. Here’s everything you need to know before you order.

Order K1 Ketones Available Now

What Are K1 Ketones? (And Why C5 Changes the Equation)

K1 is Prüvit’s next-generation exogenous ketone formula. Unlike previous Prüvit products that deliver ketones exclusively as BHB mineral salts, K1 includes a C5 ketone component, listed on the label as (D)-3-hydroxypentanoic acid sodium.

A quick chemistry note for you:

Standard ketone supplements give your body C4 ketones, four-carbon molecules that your cells use for energy when glucose isn’t available. C5 ketones are five-carbon molecules. They follow a slightly different metabolic route, which may explain why people who’ve already tried standard ketones sometimes respond differently to K1.

I want to be transparent here: the research on C5 ketones in supplement form is early-stage. What I can tell you from clinical practice and from studying the physiology is that the addition of a second ketone substrate is logical, and the anecdotal responses we’ve seen within the FastingON community have been consistently positive.

The M3™ Matrix Blend: what’s actually in the formula

Each K1 sachet (16.9g) contains:

  • DL-3-hydroxybutyric acid sodium, calcium and magnesium (the BHB mineral salts)
  • (D)-3-hydroxypentanoic acid sodium — the C5 component
  • Glycine — an amino acid that supports metabolic function
  • Vitamin B6 (100% DV) and Vitamin B12 as methylcobalamin (100% DV)
  • Calcium (35% DV), Magnesium (21% DV), Sodium (47% DV)
  • Only 20 calories and 4g of carbohydrate per serving

📌 FastingON Note: The high sodium content (1070mg per sachet) is relevant for people who fast. Fasting and low-carb eating naturally deplete electrolytes — so this level of sodium is a feature, not a concern, for most fasters. If you have a medical reason to restrict sodium, speak with your doctor first.

Why I Use K1 Myself. Dr. Monica’s Clinical Perspective

I’ve been using exogenous ketones personally and recommending them professionally since 2020. In that time, I’ve cycled through most of what the market offers. Here’s my honest assessment of what K1 does differently.

The most common complaint I hear from my patients about standard BHB products is the “peak and sometimes crash” pattern, strong energy for 60–90 minutes, then for some people a noticeable drop. I’ve experienced this myself with certain formulas. With K1, the energy curve feels more gradual and sustained. I attribute this to the C5 component creating what I’d describe as a metabolic handof,  as BHB levels begin to taper, the C5 substrate continues to provide substrate for energy production.

I also want to be direct about what K1 is not: it is not a weight loss pill, not a replacement for a solid fasting protocol, and not going to produce results without your commitment. What it does is lower the friction of fasting, less hunger, better focus, more stable energy,  so that you actually follow through with the protocol that produces results.

In my practice, I had a patient,  a 47-year-old woman doing 18:6 fasting for perimenopause-related metabolic slowdown, who had stopped using other brand of exogenous ketones because they made her feel jittery and then flat. I introduced K1 into her protocol in the first week of testing. Her response: “It just feels smoother.” That single word, smoother,  captures what I’ve now heard from multiple patients. It’s not dramatic. It’s consistent. And consistency is what changes metabolism long-term. — Dr. Monica Mogne | FastingON

Who K1 Ketones Are For — and Who They’re Not

K1 is a strong fit if you:

  • Practice intermittent fasting (16:8, 18:6, OMAD) and want to extend your fasting window without hunger
  • Struggle with afternoon energy crashes and want a clean, non-stimulant solution
  • Are in a GLP-1 recovery phase (post-Ozempic/Mounjaro) and want to rebuild metabolic flexibility
  • Are an athlete or high-performer who uses fasting for cognitive edge
  • Have tried standard BHB ketones and found the results underwhelming
  • Are new to ketones and want to start with the most advanced formula available

K1 is not for you if:

  • You’re pregnant or breastfeeding (always consult your doctor first)
  • You’re looking for a quick fix without committing to a fasting or nutrition protocol
  • You have a medical condition that restricts sodium intake without medical supervision

How to Use K1 Ketones With Intermittent Fasting | Dr. Monica’s Protocol

The timing of exogenous ketones relative to your fasting window matters more than most supplement guides acknowledge. Here’s the protocol I use with my FastingON patients:

One example of a Fasting Support Protocol

  • Take 1 K1 sachet 30–45 minutes before your eating window closes, OR during the first hours of your fasting window
  • This positions ketones to support the transition into deeper ketosis as liver glycogen depletes
  • Dissolve in 12–16 oz cold water. Shake well. Drink within 15 minutes of mixing

The Cognitive Performance Protocol

  • Take 1 sachet 20–30 minutes before intense mental work (presentations, deep focus sessions, studying)
  • Do not stack with other caffeine sources — K1 contains caffeine. Total daily caffeine budget applies

The GLP-1 Recovery Protocol

  • During the metabolic re-training phase post-GLP-1, use 1 sachet in the morning within the first hour of waking
  • Combine with a 14:10 fasting window minimum — see the FastingON GLP-1 Rebalance program for the full protocol.

Order K1 Ketones Today

Available in the US & Canada

K1 is now available through Prüvit for customers in the United States and Canada. Europe opens April 28, 2026.

Order through our official FastingON link: it costs you nothing extra, and it supports this platform so I can keep producing free educational content on fasting and metabolic health. 

But here’s what makes ordering through FastingON different: you get access to our private Skool community, ongoing coaching, and direct support from me personally as you go through your protocol. The product is the starting point. The community is what makes it stick.

 

Order K1 Ketones Available Now

One step after you order: fill in the form  with your name and email so I can send you your Skool access and get you set up inside the community. This form is how I make sure no one gets left behind.

K1 Ketones + Fasting Protocol
 

Frequently Asked Questions About K1 Ketones

Does K1 break my fast? K1 contains 20 calories and 4g of carbohydrate per serving. Strictly speaking, any caloric intake breaks a pure water fast. However, within a metabolic or therapeutic fasting context, the kind I practice at FastingON, the ketone elevation K1 produces maintains the fat-burning and cognitive benefits of fasting while removing the physiological stress of prolonged energy deprivation. For most fasting goals, K1 does not  disrupt the fast.

What is the difference between K1 and Prüvit’s NAT ketones? NAT ketones are C4-only BHB mineral salts — effective, well-studied, and my original recommendation for years. K1 adds a C5 ketone component ((D)-3-hydroxypentanoic acid sodium) alongside the BHB, which I believe creates a more sustained energy profile for many users. Think of NAT as reliable and proven; K1 as the evolution of that formula.

Will K1 show up on a blood ketone meter? Standard blood ketone meters (Keto-Mojo, Precision Xtra) measure BHB only. Because K1 includes C5 ketones, which are metabolized differently and not measured by these devices, your meter reading may be lower than you expect even when K1 is actively working. This is not a problem. It simply means your meter is giving you an incomplete picture of what’s happening metabolically.

Can I take K1 while doing extended fasting (24+ hours)? Yes, and I often recommend it for 24–48 hour fasts to support mental clarity and reduce the risk of electrolyte depletion. The mineral profile in K1 (calcium, magnesium, sodium) is particularly valuable during extended fasting windows when electrolyte losses accelerate. Use 1 sachet per 12-hour fasting block as a guideline.

Is K1 available outside the US and Canada? K1 opens for European customers on April 28, 2026, through the Prüvit global store. If you are in Portugal, Germany, Sweden, or elsewhere in Europe, check back on April 28 or join the FastingON newsletter to be notified the moment your region goes live.

How many sachets should I order for a 10-day protocol? For the FastingON K1 Challenge (10 days), I recommend 10–20 sachets, one per day, with an optional second serving on high-activity or extended fasting days. A standard box gives you enough for a full challenge with buffer to assess how your body responds before committing to a larger order.

 

Explore More From FastingON

Partner disclosure: FastingON is an independent Prüvit Partner. This page contains affiliate links. Dr. Monica Mogne personally uses and recommends the products featured on this site. Medical disclaimer: The information provided on FastingON is for educational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional before starting a new supplement or fasting protocol. Individual results vary. Author: Dr. Monica Mogne, ND | Fasting  & Advanced Nutrition Coach | FastingON | fastingon.com Published: April 20, 2026 | Last updated: April 20, 2026