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Alternate Day Fasting

by | Jun 7, 2020 | FASTING METHODS

The Big Idea of Alternate Day Fasting

Alternating between eating one day and fasting the next day can reduce caloric intake and retrain eating habits.

Deprivation diets don’t work. No matter how much weight you can lose, the rigmarole of counting calories and food stress is more than most people can tolerate for days let alone months. Alternate-day fasting (ADF) is an appealing alternative that helps you lose weight without all the tedium of traditional dieting.

The idea behind ADF is simple – eat one day, don’t eat the next. And because it’s so easy to follow (spoiler alert: you can even have food on your ‘fast’ days), alternate-day fasting has become one of the most popular and widely-researched branches of intermittent fasting.

No adverse effects have been reported in ADF’s numerous studies. And if you can endure slight discomforts like mild headaches and hunger for a week, scientists say that alternate-day fasting actually decreases overall hunger while increasing your sense of fullness.

What is Alternate Day Fasting?

As the name implies, ADF is a continuous cycle of fasting one day and eating the next. But it’s a little deeper than that. The parameters for alternate-day fasting studies include a 36-hour fast followed by a 12-hour refeeding period. This means that even on off days, you’re still practicing intermittent fasting to some extent.

One of the reasons that alternate-day fasting has a greater adherence rate than calorie-restricted diets is that you can eat whatever you want during your eating days, also known as ‘feast’ days. But the really cool part of this fasting method is that you can eat up to 500 calories on your fasting days and still reach all the benefits. Sort of similar to the Fasting Mimicking Diet.

You might worry that such an on-again-off-again relationship with food could either cause or worsen an eating disorder. But there’s no need to fear: a study of 59 adults showed no increase in disordered eating behavior after eight weeks of alternate-day fasting.

Benefits of Alternate Day Fasting


While calorie-restricted diets force you to scrutinize every bit of food you take in – calorie logs…are you serious? – ADF is mostly hands-off. This means you can enjoy a night out with friends, have a glass of wine, and feel like a human even when you’re in the process of losing weight. No more, “I wish…but I’m dieting” excuses. You just have to plan your social activities for fast days.

May reduce inflammatory bowel disease

Studies in both mice and humans have shown that alternate-day fasting and other intermittent fasting methods can reduce inflammatory bowel disease. Scientists have observed an increase in beneficial bacteria in the course of these fasts, which produce short-chain fatty acids that repair the gut lining.

Long-term weight loss

Weight loss is one of the most widely reported benefits of alternate-day fasting. While people tend to scoff at the YouTube videos highlighting 100+ pounds of weight loss, study after study shows that ADF is a reliable way to lose weight and keep it off. (This applies to both the obese and non-obese.)

Though long-term weight changes are similar to calorie-reduction study groups, the fat mass/lean mass ratio was more favorable in alternate-day fasting groups. This suggests that ADF spares lean muscle mass better than calorie restriction.

Cardiovascular health

Several studies show that ADF is associated with cardiovascular disease prevention. It’s not known exactly why, but research indicates that several markers of inflammation are lowered on fasting days, notably the inflammatory amino acid homocysteine.

Risks of Alternate Day Fasting

No moderate or serious risks have been reported in alternate-day fasting studies to date. That said, slight dizziness, headaches, and fatigue have been reported. Doctors say that hunger is normal during a fast, but they recommend stopping a fast if you start to feel unwell in any way.

Always consult your doctor before starting a fasting regimen, especially if have these conditions:

  • Heart disease
  • Liver and kidney disease
  • Epilepsy
  • Pregnancy
  • Eating disorders

How to do Alternate Day Fasting

Alternate between fast and feast days.

On day one, fast the whole day. On day two, eat all your snacks and meals into a 12-hour window, and don’t consume more than 500 calories. Studies show that it doesn’t matter whether you graze throughout the day or eat all 500 calories at once, so you can experiment with what works best for your appetite.

Doctors and fasting experts recommend drinking plenty of water during your fasting days. And lucky for you, coffee and tea are allowed. (Just go light on the sweetener and cream!)

  • Day 1: fast. Eat no more than 500 calories worth of food in a 12-hour window
  • Day 2: feast. Eat whatever you want, and enjoy it
  • Coffee and tea are allowed

fasting methods

Intermittent Fasting (IF)

Strategy that combines periods of eating with periods of fasting into a regular schedule.

Fasting With Water

The purposeful abstention of all food – solid or liquids – except for water. 

Dry Fasting

Dry Fasting

DF is the abstinence of food and water. Total. Abstinence. Dry!

Medical & Healing fasts

Medical & Healing Fast

Medical/therapeutic fasting is – eating nothing for medical advancements and natural healing.

Time Restricted Eating

The philosophy that aligns mealtimes with your natural circadian rhythm.

Fasting With Juice

Combine all your fruits & veggies into delicious juice for a select period of time.

Ketogenic Fasting

Ketogenic Fasting

Combines keto dieting principles with routine periods of fasting for enhanced fat loss. 

Fast for Religion

Spiritual & Religious

Spiritual and religious fasts have been part of almost every culture and religion throughout recorded history.

Prolonged Fasting

Fasting for 48 hours and over to
achieve health benefits and clarity.

Fasting With Food

Also known as Fasting Mimicking Diet (FMD), eating specific macronutrients to keep your body in a fasting state. 

Alternate Day Fasting

The idea behind ADF is simple – eat one day, don’t eat the next.

Detox Cleanses

Detox & Cleanse Programs

 Focus on improving liver health, the main detox organ, and nearly all of them enhance elimination and digestion.