Types of Fasting: Every Method Explained
“Fasting” is not one practice. It is a family of them, and the differences between the members matter more than most introductions admit. Some methods change only when you eat. Others remove food for days at a time. A few remove water as well.
The clearest way to tell them apart is by two questions: how long the fast runs, and what you are allowed to drink while it does. Duration decides which biological stages you reach — glycogen depletion, ketosis, then autophagy. Permitted liquids decide how sustainable and how safe the fast is once you get there.
Below are all 52 guides on this site, grouped so you can start wherever you are. If you are new to this, read intermittent fasting first, then electrolytes. Everything here is logged against a real 52-week experiment, not written from theory alone.
Protocols & Durations
The main types of fasting, grouped by how long you go without food and what you allow yourself to drink. Start here if you are deciding which method to try.
- Intermittent FastingMethods, benefits and how metabolic switching works.
- 24 Hour FastWhat happens in the body during a one-day fast.
- 48 Hour FastGlycogen depletion, rising ketones and the metabolic switch on day two.
- 72 Hour FastBenefits, hour-by-hour timeline and how to do it safely.
- 5-Day FastDay-by-day physiology of a five-day fast, plus weight, muscle and safety.
- 1-Week FastSeven days without food: the metabolic switch, deep ketosis, muscle sparing and refeeding.
- Water FastingThe baseline engine of the One Year Fast.
- Wet FastingPermitted liquids and adherence benefits.
- Dry FastingSoft vs hard dry fasting, risks and physiology.
- Herbal FastingTeas and botanicals that support autophagy, digestion and calm.
- One Year Fast vs. Intermittent FastingHow the OYF protocol compares to 16/8 and OMAD.
The Science of Fasting
What actually changes inside the body once food stops arriving — the fuel switch, the hormones and the cellular housekeeping that follow.
- AutophagyCellular cleanup, timing and how to amplify it.
- KetosisBHB, ketone monitors and reading your numbers.
- LipolysisHow the body breaks down stored fat into usable fuel.
- Insulin SensitivityHow cells respond to insulin — and how fasting can improve it.
- Metabolic FlexibilitySwitching between burning carbs and burning fat.
- Fasting & HGHHow growth hormone surges during a fast to protect lean muscle and mobilise fat.
- HibernationMetabolic parallels between fasting and hibernation.
Muscle, Training & Recovery
Keeping and building lean mass while fasting, training in a fasted state, and helping the body recover between sessions.
- HypertrophyBuilding muscle while running a One Year Fast.
- SarcopeniaPreventing age-related muscle loss on a fast.
- Fasting & ExerciseTraining safely inside a fasted state.
- Ketosis & WorkoutsTraining in ketosis without losing performance.
- Creatine + FastingCreatine timing, safety and muscle retention.
- Amino AcidsMuscle preservation, BCAAs and refeeding.
- Fasting & MassageCan massage support a fast — benefits, best techniques and safety.
Hydration, Nutrition & Supplements
What to drink, what to supplement, and how to break a fast without undoing it.
- ElectrolytesSodium, potassium and magnesium during a fast.
- Hydronated WaterHydrogen-rich water and cellular hydration.
- Vitamins & FastingWhich supplements help during a fast and which belong in the eating window.
- SpirulinaWhy spirulina is the ideal transition superfood.
- Peptides & FastingHow peptides — GLP-1s, growth-hormone analogues and experimental compounds — interact with fasting.
- Fasting & Copper CupsTamra Jal, hydration, copper as a trace mineral and what the evidence supports.
Does This Break My Fast?
The everyday grey areas — the things people are least sure about once a fast is underway.
Tracking & Tools
Measuring what is happening rather than guessing: monitors, wearables, definitions and a calculator.
- Fasting Weight Loss CalculatorEstimate fat loss versus water weight for a fast of up to 72 hours.
- Ketones vs. GlucoseHow glucose monitors and ketone readers differ — and why to track both.
- Ketones: Blood vs. BreathBlood meters measure BHB, breath meters measure acetone — why the numbers never match.
- Smart ScalesWhat bioelectrical impedance really measures during a fast.
- SmartwatchesWearables that pair well with a fasting protocol.
- Fasting GlossaryPlain-language definitions of key fasting terms.
Light, Rhythm & Environment
Fasting does not happen in isolation. Daylight, sleep, season and contact with the ground all push on the same biology.
- Fasting & SunlightCircadian rhythm, vitamin D and why daylight reinforces the same biology as fasting.
- Fasting & Red LightRed light therapy and fasting: mitochondria, inflammation, recovery and hormesis.
- Fasting & SeasonsPhotoperiod, seasonal phenotypes and the environmental signals modern life removed.
- Fasting & SleepHow fasting and sleep influence one another — hormones, ketosis and tips.
- Fasting & EarthingGrounding and fasting — shared evolutionary roots and what the evidence shows.
- Fasting & EnvironmentHow responsible fasting may lower your environmental footprint.
- Fasting & Carbon FootprintA 15-part series on food emissions, land, water, waste and eating less.
Mind, Spirit & History
Fasting is older than the science of it. These pages cover the traditions, claims and characters that shaped how we think about going without food.
- PranaThe ancient concept of life force — breath, nutrition and fasting.
- InediaThe historical mystery of living without food — accounts and science.
- BreatharianismThe spiritual belief of living without food — origins, claims and science.
- Fasting & CatharsThe medieval movement that made fasting the centre of spiritual life.
- Fasting & Nikola TeslaEnergy, frequency and the body as a bio-electrical engine.
Common Questions
- What are the main types of fasting?
- The most common types are intermittent fasting (daily eating windows such as 16/8 or OMAD), extended fasts measured in days (24, 48 and 72 hours), water fasting, wet fasting (water plus other non-caloric liquids), dry fasting (no food and no water) and herbal fasting (teas and botanicals only). They differ mainly in duration and in what liquids are permitted.
- What is the safest type of fasting?
- Intermittent fasting is generally the most forgiving starting point, because the fast is short enough that hydration and electrolytes rarely become a problem. Longer fasts require more preparation, and dry fasting carries the highest risk because it removes water as well as food. Anyone with a medical condition, or who is pregnant, underweight or taking medication, should speak to a doctor first.
- Which type of fasting is best for weight loss?
- No single method has a monopoly on fat loss — total energy deficit over time matters more than the schedule. Intermittent fasting suits most people because it is sustainable week after week, while longer fasts produce faster short-term scale movement, much of which is water weight in the first day or two.
- How long does it take to enter ketosis when fasting?
- Most people begin producing meaningful ketones somewhere between 12 and 24 hours into a fast, once liver glycogen is largely depleted, with deeper ketosis building through days two and three. The exact timing depends on your last meal, activity level and metabolic flexibility.
Fasting & Carbon Footprint
A 15-part series on the environmental side of eating less: food emissions, land and water use, waste, the rebound effect and what a year of fasting could actually measure.
- What Is a Carbon Footprint?
- The Environmental Cost of Food
- Eating Less: Does It Reduce Emissions?
- Food Production
- Food Waste
- Agricultural Land
- Water Consumption
- Food Miles
- Fasting vs. a Plant-Based Diet
- Plant-Based Eating
- Can Fasting Reduce Our Food Footprint?
- The Rebound Effect
- Your Personal Food Carbon Footprint
- The OneYearFast Environmental Experiment
- Could Fasting Be an Environmental Choice?
Fasting Through History
Long before it was studied, fasting was practised by physicians, philosophers, mystics and reformers. Their accounts sit alongside the science in a separate index.
Browse Fasting Figures →I am not a medical expert. This website documents a personal experiment born out of curiosity. I am not offering medical advice, nor am I encouraging anyone to replicate this protocol. Consult a doctor before making any drastic dietary changes.