QoFast
intermittentintermediate18h fast / 6h eat

18:6 Fasting Schedule: A Step Up from 16:8

FASTEAT
18h6h

18:6 extends the daily fast by two hours, deepening ketosis and pushing growth hormone higher. It's the natural next step for someone who has been doing 16:8 for a few weeks and wants more metabolic benefit without committing to OMAD.

How 18:6 works

Common eating windows are 13:00–19:00 or 12:00–18:00. Two meals fit comfortably; some people eat one large meal plus a smaller closer. Black coffee, tea, and water are fine outside the window. Add a pinch of sea salt to morning water if you get headaches in the first week.

A sample day

  • 07:00Wake up. Water + electrolyte pinch.
  • 10:00Black coffee. Water.
  • 13:00Break fast: protein + vegetables + complex carb.
  • 16:30Smaller second meal: yogurt, fruit, nuts.
  • 19:00Close eating window.
  • 19:00–13:00Fasting window. Water and unsweetened tea.

What happens in your body

Physiological milestones reached during a 18-hour fast.

  1. h4

    Blood sugar normalizes

    Insulin drops back to baseline as your last meal finishes digesting.

  2. h8

    Glycogen burning begins

    Your liver starts releasing stored glycogen to keep blood glucose steady.

  3. h12

    Glycogen depletion

    Liver glycogen runs low; the body shifts toward fat for fuel.

  4. h14

    Fat burning accelerates

    Lipolysis ramps up — stored triglycerides break down into free fatty acids.

  5. h16

    Mild ketosis starts

    The liver begins producing ketones from fatty acids. Mental clarity often improves here.

  6. h18

    Growth hormone rises

    HGH increases up to 5×, supporting muscle preservation and tissue repair.

What to eat

Six hours leaves less margin for poor choices, so prioritize density: a fist of protein, half a plate of non-starchy vegetables, a fist of carbs around training, a thumb of healthy fat. Drink ~2.5 L of water across the day to stay ahead of dehydration.

How to break the fast

  • Bowl of vegetable curry with chicken and rice
  • Steak with sweet potato and broccoli
  • Tofu stir-fry with quinoa
  • Greek salad with grilled fish

Who it's for

  • Intermediate fasters comfortable with 16:8
  • People targeting steady fat loss
  • Those who naturally don't want breakfast

Benefits

  • Reaches mild ketosis reliably most days
  • Higher growth-hormone surge than 16:8
  • Two meals fit comfortably in 6 hours

Risks & cautions

  • Hunger waves at hours 14–17 are common in the first week
  • Not for people with a history of disordered eating
  • Watch sodium and magnesium intake; deficiency symptoms appear faster than on 16:8

Frequently asked questions

Is 18:6 better than 16:8 for fat loss?
Slightly, on average. The longer fast deepens ketosis and pushes growth hormone higher, which favors fat oxidation. The bigger lever for most people is total calories — a tighter window naturally trims them.
Should I take electrolytes on 18:6?
If you get headaches, fatigue, or muscle cramps, yes — a pinch of sea salt, 200–300 mg of potassium, and 200 mg of magnesium will usually fix it. People eating salty whole foods inside the window may not need supplementation at all.
Can I drink bone broth during the fasting window?
Strictly speaking, bone broth has calories and breaks the fast. If you're using 18:6 for autophagy, skip it; if you're using 18:6 for body composition only, a small cup is unlikely to disrupt your goals.
How is 18:6 different from OMAD?
18:6 lets you space two meals plus a snack inside the window — easier to hit protein and calorie targets. OMAD compresses everything into one meal, which is logistically harder for most people but produces longer continuous fasting time.

Related schedules

Track your 18:6 fast in QoFast

Live timer, milestone tracking, water and electrolyte logging — free on iOS & Android.

Download on the App StoreGet it on Google Play