Fast Diets For Dummies
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People have been fasting (in other words, not eating for a while) for centuries to prevent disease and strengthen the body. Fasting is also a safe way to lose weight.

This Cheat Sheet gives you an overview of the basic principles of fasting, including what you should and shouldn't drink, so you can implement it into your routine and start your journey toward more vibrant health.

The basic tenets of fasting practices

By definition, fasting is the abstinence from eating. As a practice, cultures in all parts of the world have observed some form of fasting. In fact, you can fast in differing ways, as described below.

Regardless of which method you choose, be sure and stay hydrated by drinking plenty of fresh filtered water.

Here are the basics, and some tips, for each type of fasting method:

Intermittent fasting:

  • Once or twice a week, you abstain from eating for 24 hours.

  • For most people, the easiest fast to complete is a dinner-to-dinner fast, meaning you eat dinner on, say, Tuesday and don’t eat anything again until dinner on Wednesday.

  • Coming out of the fast, aim to choose foods with the highest nutritional value, such as grass-fed, free-range meats and poultry, organic vegetables, and raw or sprouted nuts and seeds. Avoid junk food.

The 5:2 diet:

  • Choose two days each week in which you only consume 500 (for women) or 600 (for men) calories.

  • Split the daily caloric limits roughly evenly between breakfast and dinner (for example, 250 calories at breakfast and 250 calories in the evening).

  • Choose foods that are low on the glycemic index and that don’t unnecessarily raise your blood sugar levels.


  • Micro-fasting involves fasting every day of the week.

  • Spend 16 hours fasting (it includes time that you’re asleep) and 8 hours not fasting (for example, fast from 10 p.m. Tuesday through 2 p.m. Wednesday).

  • Try to schedule your largest meal of the day to occur after you work out.

The Warrior Diet:

  • To return to an ancestral eating pattern, each day is split between a period of undereating (to occur during the daytime hours) and overeating (to occur during evening hours).

  • While undereating, choose live foods, such as vegetables, some fruit, and light protein.

  • During the overeating period in the evening, eat one large meal starting with subtle-tasting vegetables, then protein, and then carbohydrates or fats.

What you can drink during fasting

As a general rule, when fasting, you’re only able to indulge noncaloric beverages. To fast, after all, means to abstain. This means that, for the most part, food is something that needs to be set aside in the hours that you’re fasting. However, you can enjoy several drinks during your fast, including the following:

  • Black coffee

  • Black tea

  • Green tea

  • Herbal teas, such as peppermint, chamomile, or rooibos

  • Homemade light broths

  • Sparkling water

  • Unsweetened coconut water

  • Water

Don’t underestimate the power of water. The human body consists of about 75 percent water. In fact, water is vital in the performance of bodily and cognitive functions. However, the typical American only drinks 2.5 glasses of water a day, far short of the recommended eight glasses.

Staying hydrated while fasting can help ensure optimization of the fast, including allowing fat and toxins to be transported out of the body.

What you shouldn't drink during fasting

Anything with calories in it is off limits, because it will break your fast. This includes all soda and juices. The only exception to this rule is if you’re following a controlled fast, such as in the Warrior Diet or the 5:2 diet, where fresh fruit and vegetable juices are permitted in moderation.

What you shouldn’t drink when fasting includes the following:

  • Alcohol: Alcohol is quite calorically dense, so stay away from it.

  • Any diet beverages: They include soda, tea, and other similar drinks that contain artificial sweeteners, including aspartame, Splenda, and stevia.

  • Juice: During a strict fast (such as intermittent fasting), juicing isn’t allowed. But if you’re following a controlled fast, such as the 5:2 diet or the Warrior Diet, then fresh vegetable and fruit juices are allowed, such as carrot and ginger juice.

  • Sugar- and/or cream-laden coffee or tea: Anything with calories in it will tax your digestive system and sabotage a strict fast. Avoid any such additives to your coffee or tea.

Understanding the glycemic index

The glycemic index (GI) is an indicator of how quickly your body’s blood sugar will rise after eating a particular food. No matter what you eat, your blood sugar will temporarily increase as your pancreas secretes insulin into the bloodstream.

However, how much your blood sugar increases (and you don’t want it too spike too much) depends on what kinds of foods you eat, particularly carbohydrates.

Foods that are mostly fat or protein don’t raise the blood sugar as much (and don’t have as high of a glycemic index) as carbohydrates do so the GI mostly pertains to carb-heavy foods, such as grains and fruits.

In the GI, each food gets a score out of 100. You want to stick to food choices that have a score of less than 50. Foods with a score of less than 50 take longer to digest and don’t induce as much insulin to be released into the bloodstream. This is especially pertinent on fasting days, if you’re adhering to either the 5:2 Diet or the Warrior Diet, as you eat some food during the fast. Your fast will be incredibly difficult to successfully complete if you experience a spike in blood sugar.

Typically, foods made from grains come with a high GI score. Dairy can also be problematic, particularly if you’re lactose-intolerant or have difficult digesting dairy.

Because fasting and the Paleo Diet complement one another nicely, you should completely cut grains and dairy from your diet and focus on getting your carbohydrates (and the nutrients you typically get from grains and diary) from fruits, vegetables, and some carb-rich nuts, such as cashews.

Be careful with how much fruit you consume. Although fruit is bursting with nutrients, some fruits are also quite sugar dense, and some are high glycemic, such as pineapple and melon. Stick to vegetables and lower glycemic fruits, such as berries.

You can find a glycemic index chart online by typing “glycemic index chart” in your favorite search engine.

About This Article

This article is from the book:

About the book authors:

Dr. Kellyann Petrucci, author and nutritionist, appears on various news streams nationally and conducts workshops and seminars worldwide to help people feel — and look — their best. She is also the author of the popular website and gives daily news, tips and inspiration on twitter @drkellyann. Patrick Flynn, a fitness minimalist, is the coauthor of Paleo Workouts For Dummies, and the driving force behind a top 500 Health and Wellness blog

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