Table 1

Examples of fasting practices from ancient and modern societal practices

Fasting practicePattern of fastingDietary restriction during fasting
Religious practices
 Ramadan (Islam)29 or 30 consecutive days of fasting during daylight hoursNo food or liquids consumed
 Yom-Kippur (Judaism)1 day of fasting for 24 hoursNo food or liquids
 Proşadhopavāsa (Jainism)Fasting on day 8 and 14 of the lunar cycleAbstinence from the four categories of consumables:

  1. Food that satisfies entire hunger such as rice, wheat, vegetables.

  2. Water.

  3. Sweets.

  4. Oral fresheners after meals.

 Lent (Christianity)Fasting for 40 days, fast during the day and breaking fast at sunsetAbstinence from meat, eggs, dairy products, olive oil and alcohol
 Baguan zhai (Buddhism: eightfold fast)Do not eat after noon (midday), break-fast the next morningAbstinence from meat and fish
Non-religious practices
 Time-restricted eating, for example, 16/8Fasting for 16 hours and eating within an 8-hour periodNo particular dietary restriction during feeding window, however, typically results in un-intentional total caloric reduction
 Alternate day fasting, for example, 5:2 protocolCalorie restriction on 2 days of the weekNo particular dietary restriction but significant calorie restriction
 Modified alternate day fasting for example, modified 5:2 protocolIntake of up to 40% of energy requirements on 2 days of the weekUp to 40% of recommended energy requirements but no particular dietary restriction