Serenity and Fire with Krista

Fasting Without the Chaos: Intermittent, 24-Hour, and Beyond

• Krista Guagenti

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0:00 | 25:09

Fasting doesn’t have to feel extreme, confusing, or stressful, but the way it’s talked about online often makes it feel exactly that way.

In this episode of Serenity & Fire, Krista breaks down fasting without the chaos. From intermittent fasting to 24-hour fasts and beyond, she explains how fasting actually works in the body and how to choose the right approach based on your metabolism, hormones, stress levels, and health goals.

You’ll learn:
💚 Why 18 hours is often the most effective fasting window for insulin repair
💚 When fasting helps metabolic health and when it can backfire
💚 The difference between fasting for performance vs fasting for healing
💚 Why feast-and-famine works for some people and not others
💚 How autophagy really works (and why consistency matters more than extremes)
💚 The biggest mistake people make when breaking a fast and how to avoid undoing your progress

This episode is about clarity, not restriction. Strategy, not punishment. And building metabolic health in a way that’s sustainable, grounded, and actually works long term.

Tune in next week, Krista dives into lab data and what your numbers may or may not be telling you. 

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Roadmap For Deep Dive On Fasting

Clarifying Kids And Sugar

Meals Over Constant Snacking

Rethinking Carbs And Exercise

Why Post-Workout Carbs Work Better

The Case For 18-Hour Fasts

Intermittent To Multi-Day Fasting Spectrum

Feast Famine: Who It’s For

Krista’s Personal Protocol And Lessons

Choosing Your Fasting Dose

Autophagy Basics And Timing

How To Break A Fast Safely

What Does Or Doesn’t Break A Fast

Labs Teaser And Next Steps

Disclaimer And Listener Invitation

Support The Show And Spa Offer

Krista

Welcome to Serenity and Fire, the podcast where wellness meets grit. I'm your host, Krista Guidenti, founder of Panacea Luxury Spa Boutique. Join me as we dive into the intriguing world of biohacking, clean living, cutting-edge spa trends, and the hustle, grind, and grit of entrepreneurship. From my personal battles with weight management, infertility, and the 30-year journey to create and launch my dream business, to building a sanctuary for those who have been touched by cancer, I'm here to share real talk, inspire big dreams, and spark a passion for holistic living inside each and every one of you. So let's dive in. Welcome back to Serenity and Fire. After wrapping up my five-part sugar series and then sharing my personal ketosis and multi-day fasting experience, I realized there were still a few really important conversations we hadn't fully unpacked. So in this episode and in my next episode, I want to dive really deep into everything fasting: intermittent fasting, 24-hour fast versus multi-day fasting, how to set up your own fasting routine, how to properly break a fast, how and when your body actually truly hits autophagy, and what our lab data is and isn't telling us. This is where awareness turns into long-term strategy and where everything we've talked about becomes actionable. But if you listen to as many experts and podcasts as I do, all of this can be super confusing. You hear one expert say to fast every day, another says to feast and famine, another says women shouldn't fast at all. And then suddenly metabolic health feels more stressful than sugar ever was. So in these next couple episodes, I'm going to bring it all together for you. We'll talk about everything I mentioned above, including why some experts recommend 18-hour intermittent fasting, where intermittent fasting actually fits into your whole story, when fasting can become too much, and then when doing a feast-famine diet makes sense and when it doesn't. And then we'll also get into how to interpret your lab work beyond those normal guidelines and how to know what may or may not actually apply to you. But first, I want to revisit something. In the last episode of my sugar series, there were a couple of things I mentioned that I wanted to provide a little clarification on. The first one is around the topic of kids and sugar. I had mentioned that kids are not small adults and that kids process sugar differently than adults. What I meant when I said that is that children's bodies are still building neural pathways, they're still developing appetite regulation, they're still wiring dopamine and reward systems, and they're still learning how to interpret hunger and fullness. So biologically, they process sugar very differently than adults. What I was not saying is that you as a parent, if you're giving your kids sugar, are doing everything wrong. I also was not saying that kids should never have sugar. What I am saying is that early patterns matter more because our children's systems are still forming. Their bodies and brains are still under construction. So their appetite cues, reward pathways, and blood sugar regulation systems are still developing, which means repeated sugar exposure doesn't just affect energy in the moment. It helps train those systems long term. So we want to shift away from that rhythm and mindset of constant grazing and snacking to a more focused meal mindset, meaning that those meals are balanced with proteins, clean nonprocessed foods, and less constant sweetness. Because physiologically, meals create insulin rise, which then leads to insulin fall, clear hunger and fullness signals, and metabolic rhythm. But constant snacking creates chronically elevated insulin, blurred hunger cues, and dependence on quick energy. It's not that all snacks are bad necessarily. It's just more about the fact that the body learns hunger and fullness best when it has clear beginnings and endings. So that is what I meant when I said meals, protein, real food, and less constant sweetness. The second thing I wanted to provide some clarification on is around the topic of carbohydrates and how they fit into this whole sugar discussion. When can we have them? And when do we not have to worry about them creating complete metabolic chaos in our bodies? I had mentioned that carbs are best after exercise. What I meant by that is that you should eat carbohydrates after you exercise, not before. But as I thought more about that statement, I wondered if that might have been confusing for you and maybe left you wondering if I meant that you should eat carbs before exercising, which is what I always did when I was an athlete in high school. My teammates and I literally would devour an entire pan of macaroni and cheese before every basketball game. And we did that religiously. But we were doing that then because we were more concerned about performance than we were about metabolic health. And from an energy, power, speed, and endurance perspective, that made perfect sense back then. But it's just the opposite as an adult who isn't a high-performing athlete. And here's what I mean by this: the idea of carbloating developed in endurance and high-intensity sports because glucose, which is stored as glycogen, is the fastest fuel. Muscles in the liver store glycogen in advance. And during competition, that stored glycogen is rapidly burned for speed, power, endurance, and repeated bursts of effort. So carbloating before competition is designed to maximize fuel availability, delay fatigue, and improve performance during a single event. In other words, the goal for us back then was to fill our tanks, not to improve insulin sensitivity. And that makes sense for young athletes because as a high school athlete, I likely had high muscle mass, daily training, excellent insulin sensitivity, low baseline inflammation, and low stress hormones, at least, you know, relative to what we have as an adult. In that context, insulin worked efficiently, glucose went straight into my muscles, very little was stored as fat, and recovery was fast. So pre-event carbs were used immediately, metabolically appropriate, and performance enhancing. That's a very different physiological landscape than most adults live in now. And here's why carb loading doesn't translate well to adult metabolic health. Most adults today are not training daily, they're not insulin sensitive, they're not depleting glycogen regularly, and they're not competing in multi-hour events. Instead, many adults are sedentary or inconsistently active, they're insulin resistant, stressed, they don't sleep enough, and they're eating carbs without glycogen depletion. In that environment, carb loading just raises insulin, glucose lingers in the bloodstream, excess is stored in fat, and cravings increase instead of performance. So same carbs, but different body, different outcome. So going back to when I was an athlete, carb loading before competition made sense because my body was about to use that fuel immediately. Today, most of us aren't training for an event. We're training our metabolism to work better. And those are two very different goals. Now we have to think and eat very different. Now we have to eat those carbs after we work out because for most adults post-exercise, that workout temporarily changes how your body handles glucose. Because during and after muscle contraction, muscle cells pull glucose in without needing much insulin. And insulin sensitivity is significantly increased, while glute for transporters, if you remember, I mentioned those a few episodes ago, move to the muscle cell surface. And glucose is then preferentially stored as muscle glycogen, not fat. And then carbs are used for repair, not storage. In plain English, basically what I'm saying is that exercise opens the door. So carbs go into muscles instead of staying in the bloodstream or being stored as fat. And this effect can last two to 24 hours, depending on intensity, muscle mass used, and metabolic health. So what happens if you eat carbs before you exercise instead? Eating carbs before exercise is going to raise glucose and insulin first. It still allows carbs to be used for fuel during the workout, but does not lower insulin beforehand, and it does not create the same insulin-sensitizing effect. This isn't bad necessarily. It's just less therapeutic for insulin resistance. For metabolically healthy athletes, pre-workout carbs can be fine. But for insulin resistance, cravings, or metabolic repair, post-exercise carbs are the cleaner signal. So for metabolic health, eat carbs to refill what you used, not to preload what you're not about to burn. Carb timing isn't about right or wrong, it's about context. Athletes fuel for performance. Most adults need fuel for metabolic stability first. And when I was a young athlete, carb loading before competition wasn't wrong. It was just serving a completely different purpose. Today, the goal for most of us, including me, isn't to perform a super intense athletic activity for two hours. It's to feel good every day, regulate our hunger, and keep insulin working the way it should. And when I say carbs are best tolerated after exercise, I don't mean that you need to work out because you ate carbs. I mean that exercise makes your muscles more insulin sensitive. So if you choose to include carbohydrates, having them after movement helps shuttle glucose into muscle instead of leaving it in circulating bloodstream. So when I say carbs are best tolerated after exercise, I don't mean you need to work out because you ate carbs. I mean that exercise makes your muscles more insulin sensitive. So if you choose to include carbohydrates, having them after movement helps shuttle glucose into muscles instead of leaving it circulating in your bloodstream. Or even simpler, exercise makes your body better at handling carbs. So if you're gonna have them, timing them after movement is usually the most forgiving window. Okay, now let's get back into the topic of fasting with some more context. If you've been listening to experts like Dr. Pampa and Dr. Boz, which are a couple of my favorites, you've probably heard them recommend an 18-hour fasting window, meaning that you eat within about six hours of your day and then you fast the remaining 18. That recommendation isn't random and it's not about calorie restriction. It's about insulin dynamics. And most people today eat shortly after waking, they snack throughout the day, they eat dinner late, and they often finish the night with something sweet. I know that is a pattern of behavior that I had been in for a very long time. And that means that insulin is elevated for 14 to 18 hours every single day. And that's a problem because when insulin stays elevated like that, fat remains inaccessible, hunger signals stay noisy, and metabolic repair stays muted. And for metabolically disrupted bodies, meaning insulin resistance, sugar dependence, constant hunger, stubborn fat, a 12 or even 14-hour fast often isn't enough. And that was something that took me a really long time to understand, because what happens is that insulin never fully drops and the switch never flips. But an 18-hour fast is long enough to keep insulin low for a sustained window and allow the body to fully transition out of glucose burning, begin meaningful fat oxidation and ketone production, and quiet those appetite hormones after adaptation. So when these experts recommend an 18-hour fast, it's for a very good reason. And this distinction matters because an 18-hour fast allows your body to experience a true therapeutic insulin reset. And depending on what your health goals are, this can make a big difference for you. So how do you decide what your fasting schedule should look like on a regular basis? Fasting's often talked about as something extreme, but it doesn't have to be. Intermittent fasting is the foundational layer of fasting, not the far end. So think of fasting as a spectrum. 12 hours is gonna be a normal overnight fasting. 14 to 16 hours is gonna give you gentle insulin reduction. And then 18 to 20 hours is gonna give you therapeutic insulin lowering, while 24-hour fasts are gonna give you that metabolic reset. And then when you start looking at multi-day fasts, two to five days, that's when you get into that advanced therapeutic fasting. So when we look at intermittent fasting, usually 16 to 18 hours is gonna be the most sustainable, the least risky, the highest compliance, and the most effective long term for restoring that metabolic flexibility, which is really what our goal is. And this is why intermittent fasting is often recommended daily while longer fasts are periodic. And this is where a lot of confusion starts, because you may have heard some experts, and Dr. Pompa's one of them, talk about a feast and famine approach to eating. This is where you intermittently fast on some days, do a 24-hour fast weekly, and then intentionally feast with higher carbohydrate, low protein intake on other days. He has this philosophy because he believes our bodies crave variability and that this leads to increased metabolic flexibility. He's not wrong, but many people misinterpret this, and here's what I mean. Dr. Pompa's feast famine philosophy is rooted in evolutionary biology, and the theory is sound because humans evolved with food variability. Periods of scarcity or famine were followed by periods of abundance or fasting. And this theory is true. The body adapts best when it experiences changing inputs, not constant sameness, and variety can prevent metabolic stagnation. Where people get tripped up, though, is with timing and who this type of routine applies to. The key lesson here is that you cannot create flexibility in a metabolically inflexible body through chaos. And this is the part that often gets skipped on social media, but it's so critically important because for a metabolically disrupted person, in other words, for someone who's insulin-resistant, sugar-dependent, craving-driven, or has poor hunger signaling, daily intermittent fasting is not a state of rigidity or torture. It's rehabilitation. And those bodies really need predictability, insulin calming, reduced frequency, and stable signaling. For them, alternating fasting and that famine cycling too early and having high carb feast days and experiencing frequent metabolic switching can actually worsen dysregulation, not improve it. So when does feast famine make sense scientifically? It's really going to be for people who already have low fasting insulin, stable hunger cues, good sleep, low stress, no food obsessions, and metabolic flexibility is already developing. And those bodies, periodic carb cycling, intentional feast days, and variability in their macros, which just means not eating this exact same thing every single day. Some days it might be lower carbs, some days it might be higher carbs, other days maybe more protein, and others may be more fat. For people who are metabolically balanced all the time, this can support thyroid signaling, support leptin and ghrelin sensitivity, prevent metabolic stagnation, and psychologically reduce the feeling of rigidity and torture that is so often felt by someone who isn't metabolically balanced. So when I talk about signal repair, I'm talking about restoring clarity to the body's communication system, those hunger signals, the fullness signals, the energy signals. And in a metabolically disrupted body, those signals are noisy and unreliable. Consistency, especially with eating windows and sweetness, helps quiet the noise so the signals can recalibrate. So the feast famine philosophy itself is not wrong. The mistake is in applying it too early, because it's not how you create metabolic flexibility, it's how you express it once it exists. So the feast famine philosophy itself is not wrong. The mistake is in applying it too early. Because feast famine is not how you create metabolic flexibility. It's how you express it once it exists. Okay, now let's get on to those longer fasting periods. Like when we look at the incorporation of a 24-hour fast into your diet. These kinds of fasts are often called a metabolic reset. And for good reason, because a single 24-hour fast can significantly lower insulin, increase fat oxidation, raise ketones, recalibrate appetite hormones, improve mental clarity, and reduce inflammation. For most people, this is the highest benefit to risk fast available. And then we get into multi-day fasts, so those three to five-day fasts, which go much deeper. But as I mentioned in my earlier episodes, they can also carry more risk. They can deepen autophagy and profoundly suppress insulin and activate immune renewal pathways, but they can also potentially raise cortisol, increase electrolyte loss, increase muscle breakdown risk, and stress female hormones more easily. These are therapeutic interventions, and depending on where your metabolic, physiologic, and psychological health is at, more is not necessarily always better. So when and how to set up your fasting and whether or not you do a feast famine routine and or a weekly 24-hour fast depends on you as an individual. For me, I've been doing a 24-hour fast weekly, and I really do feel so much better doing so. I have so much less inflammation throughout my body. I have less brain fog and even more energy, which believe it or not, with all the energy I already have, it's kind of hard to believe, but it's there. I was trying to do the feast famine routine where I was doing three days of intermittent fasting with high protein and low carb, and then three days of carbohydrate feasting. But what I have learned from my body is that I'm not ready for this kind of variability yet. My weight will drop like three to four pounds when I'm doing the 24-hour fast and the intermittent fasting days, but then it all comes right back on when I try to do the feast days. So I really think my insulin levels are still regulating. So I'm gonna stick with this weekly 24-hour fast and then the 18-hour intermittent fasting with high protein and low carb foods and not do the feast days until at least until I feel like I've gotten my metabolic health totally back in check. And then I'll look at incorporating the feast famine routine back into my life at that point. But the key takeaway here and the important lesson that I'm personally learning is that consistency lowers insulin and strategic variation builds flexibility, but only after consistency is established. And how you decide how long your fasting window should be is the most important question. And quite frankly, this is where many people go wrong. The right fasting dose depends on your baseline insulin resistance, your stress load, your sleep quality, your hormonal status, especially if you're a female, your history of dieting and restricting, and then your mental relationship with food. But here's some general guidance that will hopefully help. So if you're new or metabolically fatigued and fragile, most experts recommend that you start with 12 to 14 hour intermittent fasting and then eventually build to 16 hours and stay there for weeks to months. And that's actually what I did. I actually, for years, did 12 to 16 hour intermittent fasting. And it wasn't until about six months ago that I started doing those longer intermittent fasting periods and those 24-hour fasts, which in hindsight is probably what I needed to be doing a long time ago and just didn't know. And quite frankly, my eating window had just been way too long. So now I'm trying to keep it to that six hours or eight hours at the max. And I'm finally starting to notice physical and visible changes in my body, which is super exciting. Okay, so if you're insulin resistant but stable, which is really where I think I'm currently at, 16 to 18 hour intermittent fasting on most days should be good for you with that occasional 24-hour fast. There's no urgency for longer fasts if you're in this phase, but introducing longer fasts, if not stress compounding for you, of course, can be very beneficial in healing if done correctly. My health coach recommends doing a multi-day fast every few months. And this is now where I'm at. So the ultimate goal is metabolic flexibility, not endurance fasting. So some red flags that fasting could be too much for you is constant coldness, hair loss, insomnia, anxiety, loss of menstrual regularity, obsessions with food, worsening cravings, if it's raising your cortisol levels chronically, if your sleep is getting disrupted, and if you find that your hormone balance is worsening. Those are all signs of physiological stress, not healing. So learn from my experiences and make sure you're using the right tools at the right time for the right reasons. So one other thing I wanted to revisit quickly while we're talking about fasting is that one of the main goals with fasting is, of course, reaching autophagy. Remember, this is our cellular housekeeping. It's your body's natural recycling system where your cells break down and remove old damaged components like proteins and organelles, and also harmful invaders like viruses and bacteria to reuse the cellular building blocks, generate energy, and maintain overall cellular health, especially during stress or starvation. It's a vital housekeeping process in your body that cleans out that cellular junk. It prevents clutter and provides resources for new cell parts, contributing to disease prevention and cellular efficiency. Autophagy is not an on-off switch. It's more like a dial. It actually begins with that 14 to 16 hour fast and increases at about 24 hours, which is why I like incorporating that 24-hour fast once a week into my routine. And then it peaks with those multi-day fasts. But again, the key is consistency, and that's more important than intensity. You do not need extreme fasting to benefit from autophagy. So now that you know what fasting is and what type of fast to choose, let's talk about what you do at the end of your fast. Because if you don't break your fast the right way, you can undo everything you accomplish during the fast. How you break the fast is as important as the fast itself. And here's why. Breaking your fast incorrectly can actually spike insulin pretty aggressively. It can cause GI distress, it can undo metabolic signaling, it can actually make you feel pretty awful. And that's because your digestive enzymes become suppressed during the fast. So if you don't introduce the right foods gently, all of these things can happen. So the best way to break a fast is with small portions. You want to think protein plus fats first, and then minimal carbs initially, and you want to chew slowly. You also want to wait about 20 to 30 minutes before you have. An actual full meal. The first thing you put into your mouth is the most important. So make sure you're selecting gentle, easily digestible foods like bone broth plus some protein or eggs plus avocado. Greek yogurt's great as well. And also steamed vegetables are all great things that you can use to gently break that fast. You really want to avoid sugar, refined carbs, processed foods, alcohol, and huge meals. So think gentle re-entry, not celebration. And I think that's the big thing is like when we go through a fast, we're so excited that we completed the fast that we're like, oh my God, I'm so hungry. I just need to eat everything. You don't want to do that. So heed my advice and make sure that you break that fast in the right way. And when you're in your fast, remember that protein, amino acids, glucose, and insulin all spike and break a fast. So things that generally do not break your fast or interrupt autophagy are unsweetened black herbal tea, black coffee, plain electrolytes, unless they're sweetened with something like pure stevia leaf extract and flavored with something very simple like lemon juice or lime juice. Also, minerals do not break your fast. So, like sodium, potassium, magnesium, and then of course water. Okay, I really wanted to get into the lab data today, but the episode's running kind of long. So I think I'm gonna save it for our next episode because there's so much to cover, and you're gonna want to come into that episode with your eyes wide open and your mind fresh because what I'm gonna share with you is super illuminating. So stay tuned next week to hear about what your labs may or may not be telling you. And before we wrap up today, please remember that everything shared on Serenity and Fire is meant for general information and inspiration purposes only. The topics we discuss are not intended to diagnose, treat, or replace personalized medical care. So please always consult with your healthcare provider before trying anything we talk about on the show. Your health is unique and your care should be too. Okay, that's it for today's episode. Thank you so much for joining me for this deep dive on fasting. Please let me know what you've tried, what works for you, what doesn't work for you, and if any of this information that I've been sharing with you has been helpful. It's taken me years and years to learn all of this, and now I'm sharing it with you so that hopefully you don't have to go through the same frustrations I have as an adult. My hope is that you discover metabolic health much faster, much easier, and in a much healthier way than I did. So please share your stories because they mean so much to me. And as always, thank you so much for listening to Serenity and Fire. If today's episode inspired you, the best way to support the show is to follow, leave a review, and share these episodes with those you love most. And don't forget to follow us on social too at Serenity and Fire. Until next time, keep balancing Serenity with Fire. I'm Krista Guigenny, and I'll talk with you more in our next episode. At Panacea Luxury Spa Boutique, we don't just offer traditional spa treatments. We create rituals that relax your mind, restore your health, and rejuvenate your spirit. From biohacking technologies to advanced oncology trained care, everything we do is designed to help you heal on the deepest level with clean, holistic therapies, products, and amenities that are second to none. And right now you can experience two of my favorites our whole body LED lightbed or hyperbaric oxygen therapies. And as a thank you for listening, you'll get 10% off your first session when you use the code SERENITY10 at booking. What is your panacea? 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