Intermittent Fasting: Beyond the 16/8 Fad — Benefits, Myths, and How to Apply It Wisely

Unlike practically any other nutritional trend, intermittent fasting doesn’t tell you what to eat, but rather when to eat. It is a time-based protocol that alternates deliberate windows of eating with continuous hours of caloric abstinence, and it has established itself as one of the most widely practiced health habits in the world.

For decades we were told, like a mantra, that «breakfast is the most important meal of the day» and that we should «eat five times a day, every three hours, to rev up the metabolism.» Today, scientific evidence has dismantled those commercial dogmas and recovered an elementary truth: the human body is evolutionarily designed for regular periods of digestive rest.

1. The Most Common Protocols: From 12/12 to 16/8 and OMAD

There are different schemes depending on each person’s level of experience and goals:

• 12/12 (The natural circadian rhythm): Having dinner at 8:30 p.m. and breakfast at 8:30 a.m. This is the basic physiological fast that respects the cycles of light and darkness. It requires no effort and allows for optimal overnight regeneration.
• 16/8 (The star formula): 16 hours of fasting and an 8-hour window for two or three meals. In practice, this usually means having an early dinner and delaying the first meal until midday (skipping the traditional breakfast), or eating a hearty breakfast and an early afternoon snack with no dinner.
• OMAD (One Meal A Day): Fasts of 22 to 23 hours with a single large meal per day. Very popular among biohackers, although it’s difficult to cover all micronutrient and protein requirements without stomach discomfort.
• 5:2: Eating normally five days a week and restricting intake to about 500–600 calories on two non-consecutive days.

2. What Happens in Your Body During the Fasting Hours

Far from weakening the body, a digestive pause triggers a cascade of cellular repair mechanisms:

• Lower insulin and fat burning: After 10–12 hours without consuming calories, plasma insulin levels bottom out, which facilitates access to adipose fat stores through lipolysis.
• Cellular autophagy: The cellular cleanup mechanism (whose discovery earned Yoshinori Ohsumi the Nobel Prize in 2016). In the absence of circulating nutrients, cells recycle damaged proteins, aged organelles, and dysfunctional cellular components.
• Rest for the intestinal barrier: It allows activation of the migrating motor complex (MMC), a kind of «cleaning sweep» of the digestive tract that prevents abnormal fermentation and bacterial overgrowth in the small intestine.

«Being constantly in a postprandial state is a modern anomaly. Letting your stomach rest for a few hours isn’t going hungry; it’s giving your body time to clean house.»

3. Myths Debunked and Common Mistakes

Despite its simplicity, intermittent fasting is often surrounded by significant confusion:

• Myth 1: «Your metabolism slows down»: False. Various clinical trials have shown that basal metabolic expenditure remains intact (and even rises slightly due to the release of noradrenaline) during fasts of less than 48 hours. Metabolic slowdown occurs from chronic, prolonged caloric deficits, not from skipping a meal.
• Myth 2: «You lose muscle mass immediately»: If total daily protein intake is adequate and strength training is maintained, muscle is preserved with complete certainty.
• Critical mistake: Compensating with junk food: Breaking the fast with ultra-processed foods, refined flours, and sweets in the belief that «you have calories to spare» ruins all the metabolic benefits. What you eat during the eating window remains decisive.
• Permitted drinks: During the fasting hours you may have water, black coffee without sugar, tea, herbal infusions, and bone or vegetable broths strained free of fat and solids.

4. Who Should NOT Practice Intermittent Fasting

Fasting is a hormetic biological stressor (a beneficial stress at the right dose), but it is contraindicated in certain profiles:

• People with a history of, or vulnerability to, eating disorders (EDs, binge eating, bulimia).
• Women with menstrual cycle disruptions, hypothalamic amenorrhea, or low energy availability.
• People in states of extreme chronic stress, severe sleep deprivation, or acute overtraining.
• Pregnant women or those actively breastfeeding.

Calculate Your Calories and Eating Window

Remember that intermittent fasting is a tool for distributing meals across the day, not metabolic magic. If your goal is to lose fat or maintain muscle mass within your eating window, you need to know your numbers. Calculate your energy expenditure and macronutrients with our TDEE and Macro Breakdown Calculator.

The Trebellos Verdict

Intermittent fasting is not a religion or a mandatory requirement; it is an extraordinary tool for simplifying your life. It frees you from the tyranny of meal-prep containers, reduces digestive inflammation, and sharpens morning mental clarity. If you don’t have an appetite one morning, don’t eat out of social inertia; if one day you wake up hungry, eat a real, nutritious breakfast. The key lies in learning to listen to your own body’s genuine signals of hunger and satiety.