Intermittent fasting can help with weight loss when the fasting window fits your routine, lets you eat fewer calories overall, and is safe for your health (no pregnancy, eating disorder history, uncontrolled diabetes, etc.).

Key idea: “When” matters less than “consistency”

  • Weight loss mainly comes from an overall calorie deficit across the week, not a specific magic hour to stop eating.
  • For most people, a daily “time‑restricted” eating window (like 8 hours eating, 16 hours fasting) is the simplest way to structure that deficit.

Common fasting windows for weight loss

Researchers and clinicians often suggest windows that include your normal sleep to make fasting easier.

  • 12:12 or 14:10 (beginner friendly)
    • Example: Eat between 8 a.m. and 8 p.m. (12:12), or 10 a.m. to 8 p.m. (14:10).
* Good if you are new to fasting or get hungry early.
  • 16:8 (most popular)
    • Example: Eat between 11 a.m. and 7 p.m., or 12 p.m. and 8 p.m.
* Much of the 16‑hour fast happens overnight; this is why many people use “skip breakfast, finish dinner early”.
  • Weekly pattern
    • Some people use 5:2 (normal eating 5 days, 2 lower‑calorie days, around 500 kcal).
* Others alternate normal days with very low‑calorie/fasting days, but this can be harder to sustain.

In studies, intermittent fasting and regular daily calorie restriction often lead to similar weight loss, so the “best” timing is whatever you can stick to.

Better vs worse times to fast

Many dietitians recommend concentrating food earlier in the day and not eating too close to bedtime.

Often better:

  • Stopping food 2–3 hours before sleep to help digestion and alignment with your body clock.
  • A daytime eating window like 9 a.m.–5 p.m. or 11 a.m.–7 p.m., rather than late‑night eating.

Often worse:

  • Very late eating windows (e.g., 4 p.m.–midnight), which may worsen sleep and make overeating easier.
  • Frequent 24‑hour “dry” fasts or extreme fasting without medical supervision, which are not recommended for weight loss.

How to choose your timing

Use these steps to decide when you should fast to lose weight :

  1. Check safety first
    • Avoid or be carefully supervised if you are pregnant, breastfeeding, have diabetes on medication, have a history of eating disorders, or take medicines that require food at specific times.
  1. Match your lifestyle
    • Early‑riser: Try eating 7 a.m.–3 p.m. (or 8 a.m.–4 p.m.) and fasting the rest.
 * Night‑owl: Try 11 a.m.–7 p.m. and slowly bring your last meal a bit earlier.
  1. Start simple and adjust
    • Begin with a 12‑hour fast (e.g., 7 p.m.–7 a.m.), then move to 14:10 or 16:8 if you tolerate it well.
 * Aim to follow your chosen pattern most days of the week; occasional off days matter less than long‑term consistency.
  1. Focus on what you eat, too
    • Fasting alone will not overcome constant high‑calorie, ultra‑processed foods.
 * Emphasize vegetables, lean protein, whole grains, and healthy fats during your eating window to stay full on fewer calories.

Quick “forum‑style” take

If you’re asking “when should I fast to lose weight,” the practical answer is: pick an eating window that fits your life (commonly 8–10 hours during the day, ending at least 2–3 hours before bed), stick to it most days, and use it to help you eat a bit less overall while still choosing mostly whole, filling foods.

TL;DR: Most people see results with something like 16:8 or 14:10, eating between late morning and early evening and not snacking late at night, as long as total calories over the week are reduced and the approach is safe for their health.

Information gathered from public forums or data available on the internet and portrayed here.