24-Hour Fast Schedule: Hour-by-Hour Plan, Milestones, What to Expect
A 24-hour fast is the threshold where extended-fasting benefits begin. You'll cross into mild ketosis around hour 16–18, see growth hormone climb, and brush the start of autophagy right at the 24-hour mark. It's a manageable first extended fast for most healthy adults.
How 24-Hour Fast works
Run dinner-to-dinner: eat a normal evening meal around 19:00, then nothing until 19:00 the next day. Water, electrolytes, black coffee, and plain tea throughout. Plan a light activity day — walks are great, heavy training is not.
A sample day
- Day 1, 19:00Last meal: balanced and substantial.
- Day 2, 07:00Wake. 500 ml water + 1/4 tsp sea salt + black coffee.
- Day 2, 11:00Hunger wave. Water and a 20-min walk.
- Day 2, 14:00Magnesium glycinate 200 mg, water, tea.
- Day 2, 17:00Final stretch — clarity often peaks here.
- Day 2, 19:00Break fast with a small, easy meal (see below).
What happens in your body
Physiological milestones reached during a 24-hour fast.
- h4
Blood sugar normalizes
Insulin drops back to baseline as your last meal finishes digesting.
- h8
Glycogen burning begins
Your liver starts releasing stored glycogen to keep blood glucose steady.
- h12
Glycogen depletion
Liver glycogen runs low; the body shifts toward fat for fuel.
- h14
Fat burning accelerates
Lipolysis ramps up — stored triglycerides break down into free fatty acids.
- h16
Mild ketosis starts
The liver begins producing ketones from fatty acids. Mental clarity often improves here.
- h18
Growth hormone rises
HGH increases up to 5×, supporting muscle preservation and tissue repair.
- h24
Autophagy begins
Cells start digesting damaged proteins and organelles — the housekeeping phase.
What to eat
After 24 hours your gut needs gentle reintroduction. Start with bone broth or vegetable soup, wait 30 minutes, then a small balanced meal — cooked vegetables, lean protein, no heavy fat or fiber. Save the bigger meal for 3–4 hours later.
How to break the fast
- Bone broth, then scrambled eggs with cooked spinach
- Vegetable soup with shredded chicken
- Plain Greek yogurt with cooked apples and walnuts
- Dal with white rice and steamed greens
Who it's for
- • Experienced 16:8 / OMAD practitioners
- • First-timers easing into extended fasting
- • Anyone curious about autophagy without committing to 72 hours
Benefits
- • Reliable ketosis
- • Strong GH surge — supports lean tissue preservation
- • Early autophagy signals at hour 24
- • Mental clarity often peaks at hour 18–22
Risks & cautions
- • Headaches in hours 12–16 from sodium loss — drink salted water
- • Dizziness on standing — go slow when getting up
- • Don't pair with intense training
- • Anyone on glucose-lowering medication needs medical supervision
Frequently asked questions
How much weight will I lose on a 24-hour fast?
Will I be too tired to function?
Can I drink electrolytes during a 24-hour fast?
How often can I do 24-hour fasts?
Related schedules
Track your 24-Hour Fast fast in QoFast
Live timer, milestone tracking, water and electrolyte logging — free on iOS & Android.
