5 Kinds of Fasting for Different Benefits - Gut Health, Fat Loss, Brain Health & Insulin Resistance

DeLauer reintroduces the concept of fat fasting, which he hadn't discussed in years, blending the older MCT oil fast with Valter Longo's fasting-mimicking diet (FMD). The central idea is to achieve key benefits of fasting—autophagy, telomere lengthening, stem cell regeneration—without entering the extreme energy deficit that comes with pure water fasting. This appeals to people who have lost significant weight and fear losing muscle, like DeLauer himself. He is careful not to claim it outperforms a real fast; instead, he positions it as a strategic tool. The protocol is straightforward: maintain all the usual fasting liquids (water, black coffee, tea, electrolytes) but add pure fats while restricting protein and fiber to keep insulin levels rock-bottom. The fat keeps ketones elevated, providing brain fuel and a sense of energy. He warns that it's not a fat loss strategy—it's about cellular housekeeping. The psychological benefit of sipping MCT oil or eating a few macadamia nuts can make extended fast-like periods more sustainable for those who struggle with complete abstention.

DeLauer acknowledges the social media frenzy around 'sugar fasting' but separates the noise from the underlying science. He traces its roots to juice fasts his mother practiced and references Ray Peat's high-carb, low-fat concepts. He explains that strict avoidance of fat and protein while flooding the system with sugar triggers a specific hormonal response: FGF-21 rises, ramping up metabolism and fat burning. There is also a logic of forcing cells to adapt to glucose when no other substrates are present, potentially restoring insulin sensitivity in some people. However, he is cautious, noting that the response is heterogeneous—some thrive, others crash. He warns that candy-gorging versions online are distortions; the real protocol is about pure fruit juice or sucrose without any fat or protein. He insists that if someone tries it, the refeed must begin with lean protein and starch, with fats added gradually over several days to avoid overwhelming a system that has downregulated fat metabolism. He is not endorsing it for everyone and wants viewers to self-identify whether they are a 'carb responder' or 'carb crasher.'

DeLauer credits bone broth fasting as the practice that first gave him a sense of control over his lifelong IBS. He explains that water fasting temporarily degrades the gut mucosal layer, which rebuilds when eating resumes. However, the transition back to food can undo some of that progress. By adding bone broth—rich in gelatin and collagen—you provide a physical layer of protection that supports the mucosal lining while the gut is in a regeneration state, essentially getting the 'best of both worlds.' He emphasizes that this fast is gut-centric, not designed for metabolic prowess; bone broth breaks a fast. He admits that from a hunger standpoint, pure water fasting is easier for him because the saltiness and satisfying mouthfeel of broth trigger a desire to eat. For safety, he caps the protocol at 48 hours because the small influx of amino acids is not enough to fully protein-spare the body, and muscle breakdown could occur if extended.

DeLauer presents protein sparing modified fasting (PSMF) as the most aggressive fat-loss method among the protocols. He frames it within the fasting community's sometimes contradictory view of low-fat diets: water fasting is inherently a zero-fat state, so a brief period of lean protein alone is conceptually similar—just with the addition of muscle-sparing amino acids. He compares it to 'protein fasting,' where you eat nothing but lean meat. The protocol was originally used in medical settings and bodybuilding. He cautions that it's meant only for short bursts because the calorie intake becomes dangerously low; pushing beyond 2 days could lead to hormonal disruptions. He alludes to a separate video where he discusses protein sensitivity cycling, implying that occasional protein restriction followed by PSMF could have an anabolic rebound effect.

DeLauer approaches dry fasting with more caution than any other protocol. While he acknowledges its effectiveness—citing the well-known anecdote that three days of water fasting is equivalent to one day of dry fasting—he repeatedly says he doesn't think people should push it that far. He explains the mechanism of endogenous water creation from fat metabolism as a fascinating biological adaptation, likely something our ancestors relied on when water was scarce. Still, he underscores that we live in a time when cellular hydration and electrolyte balance are paramount, and he would rather see people use water fasting with proper electrolyte support. He mentions the Ramadan practice as a culturally accepted short-term dry fast, but extreme versions like Dr. Filannov's multi-week dry fasts are not what he's endorsing. He closes by saying that while he's done it and found it effective, the 'juice isn't worth the squeeze' for most people.

DeLauer touches on this bonus protocol because he believes there is a 'serious serious benefit' to pairing methylene blue with fasting. He explains that one of the challenges of fasting is reduced energy, but methylene blue directly supports the mitochondrial electron transport chain, making the body better at producing ATP from fat. This essentially turns up the cellular engine during a fast, potentially allowing for longer or more comfortable fasts. He doesn't go into detail here because he has a whole separate video on the topic, which he says he will link.

DeLauer frames this as a tool for those who find prolonged water fasting too catabolic. He contrasts it with pure fasting: fat fasts are not designed for fat loss, but for the longevity and cellular cleanup mechanisms that come from low insulin, high ketones, and protein restriction. Citing Longo's work, he explains that a high-fat, low-protein approach keeps the body in a fasted-mimicking state without forcing a severe energy deficit. He says he uses them occasionally because, as someone who once weighed 300 lbs and lost 100 lbs, he worries about muscle loss from too much traditional fasting. While he admits the approach isn't superior to a full fast, he values the cognitive boost and the ability to still drink water, coffee, tea, and electrolytes while adding MCT oil or macadamia nuts. He emphasizes that the focus should be on pure fat, keeping fiber low to drive ketones up and insulin low.

DeLauer says his mother did juice fasts when he was a kid, so the concept isn't new. The trend has returned, but he stresses that the real sugar fast involves consuming 500–600 grams of sugar from fruit, juice, or sucrose while dropping fats and protein to near zero. He points to research showing that such a fast elevates FGF-21, a compound that can increase metabolic rate and thermic energy expenditure, leading to fat burning. Additionally, forcing cells to rely solely on glucose may help some insulin-resistant individuals re-learn how to use glucose, but only if their insulin resistance isn't too advanced. He cautions that type 1 diabetics would die on this protocol, and those with pathological insulin resistance won't benefit. Breaking the fast should be done with lean protein and starch, followed by a gradual reintroduction of fats—not a cheeseburger. He does not fully endorse it but wants to give credit where due, as some people report feeling shredded and energized.

DeLauer reveals he has done a couple of dry fasts and found them effective, but he isn't sure 'the juice is worth the squeeze.' He explains that fat cells release hydrogen as they are broken down, which combines with oxygen from breathing to create molecular H₂O—effectively hydrating the body through accelerated fat burning. This underlies the anecdote that a single day of dry fasting can equal three days of water fasting in terms of results. He explicitly says he does not think people should push it that far, but he provides the information because short periods (like during Ramadan) might have some effect. He believes our ancestors went long stretches without water without harm. For most people, however, water fasting is safer, and he emphasizes staying smart, using electrolytes, and having supervision if attempting anything beyond brief stints.