1. What's the optimal amount of time to fast?

When it comes down to it, the optimal amount of time to fast is the amount of time a person can realistically spend in autophagy, considering both physical and mental factors. (In other words, you’ve still got to do life — and that has to factor into your fasting plans.) While a week-long, zero-calorie water fast is fantastic for your health, it’s not realistic for most people with a busy work schedule and family life. Based on my research, a three-day modified fast is the right mix of doable and highly impactful for your health. I find that people fall off and feel like a failure when they attempt 5 days of modified fasting, but virtually everyone finishes strong with 3 days.

2. Is a modified fast better than a water-only fast? What about juice fasts, or dry fasts?

It’s easy to get confused by the sheer number of options for different fasting types. And I’m not here to knock any of them. A water-only fast (zero calorie intake, only water to drink) is wonderful for your health, but very difficult for most people to maintain. A juice fast has a lot of benefits (and gives you an incredible boost of micronutrients), but autophagy doesn’t kick in nearly as quickly as it does other types of fasting. And a dry fast (neither water nor food allowed!) can really only be done for one day, max, to avoid some serious health issues related to dehydration. A modified fast of 3 days feels doable for most people, offers the same health benefits of a water-only fast, and is compatible with real life.

3. How does modified fasting differ from intermittent fasting or time-restricted eating?

Modified fasting is a type of intermittent fasting and includes some time-restricted eating. A 12-hour feeding window is basic common sense for good health. This is something we should be practicing all year long and doesn’t quite qualify as fasting. For autophagy to really kick in, a modified fast of 600-800 calories is needed, in addition to maintaining an “eating window” of 8-12 hours each day during the modified fast. Throughout history, people have limited their “eating window” from 7 am to 7 pm or even shorter; the modern American phenomenon of eating all day and even into the night is a product of cheap, easily available food.

4. Isn’t five days better than three days of fasting?

Based on my own research, a three-day window of modified fasting is simply more doable for the vast majority of people. And that three-day window is enough time for your body to do some serious work in autophagy, clearing out damaged cells, reducing inflammation, and improving so many markers of good health. If you want to extend your fast to five or six days, all the better! But I find that people who set out with a specific goal of five days, instead of three, have high dropout rates. Three days seems to be the magic number for a doable, realistic fast that doesn’t interfere with your social life.

5. How much weight can you lose with modified fasting?

Our first group of modified fasters (who used my Flash Fast program , which included three days’ worth of organic, prepared mini-meals), lost an average of 4 pounds in 3 days. Think about what that means over the course of a year: If you did a (modified) Flash Fast every month, that’s a possible 48-pound weight loss in one year, even changing nothing else in the year-round diet.

6. How do you start a modified fast?

It’s really simple. Choose three days in a row. Plan your plant-based, nutrient-dense meals to total 650-800 calories per day. Eat within an 8-12 hour window each day . Your satiety level will be the best if your plant-based diet is higher in protein than most vegan diets. Our first 100 beta testers of the Flash Fast reported an average highest hunger level of 3.4 on a 1 to 10 scale!

7. What should you eat and drink during a modified fast?

Liquids appropriate for a modified fast include lemon water, organic herbal tea, celery juice, and good old fashioned filtered water. I recommend including 13 grams of protein, four times per day, during the fast, as well as good omega fatty acids from flaxseed or hemp seed. You may wish to include raw greens, plus steamed vegetables or a piece of fruit. Your total intake of calories should not exceed 800 calories daily to stay within what is known, from the published clinical research, to support the benefits of fasting while still eating. If you plan your own menu for a modified fast, take special care to include plenty of micronutrients from organic sources. You can also use the Flash Fast kit, which has all the food you’ll need for three days (and allows for unlimited greens blended into your shakes, or eaten without oils added, and some non-starchy veggies or one serving of fruit is also allowable as additions, keeping you under 800 calories).

8. Should men and women do modified fasting differently?

As of this time, no one has done a study to prove or disprove that men can eat more than women during modified fasting and still gain all the autophagic and ketotic health benefits. So, to be true to the published studies, I can say only 800 calories or fewer for both genders. If I learn of any new evidence that men can follow different guidelines than that, I will update this blog post.

9. Are alcohol and coffee off-limits during a modified fast? What about decaf?

Don’t compromise your results by drinking caffeine or coffee (even decaf coffee) during your modified fast. Not only is coffee dehydrating, but it’s incredibly acidic and can undermine your results significantly. You’ll also want to eliminate alcohol from your diet during the fast, since it will tax your liver and make it harder to flush toxins and fat stores.

10. Can I exercise during a modified fast?

Yes! Most people find that they prefer workouts that are lighter or less intense while fasting, but you should feel free to listen to your body and stay as active as you wish. If your body tells you to slow down a little, be willing to respond accordingly — after all, you’re doing a lot of unseen work during your fast!

11. What should I eat after a modified fast?

What you eat after a fast is important. When “refeeding” your body after a fast, you’ll be fueling new cell growth as your body rebuilds the “broken parts” stripped down by the process of autophagy. You’ll want to eat plenty of organic fruits and vegetables, non-gluten whole grains, legumes, nuts, seeds, and only very small portions of wild-caught, free range, or grass-fed animal products (if you choose to eat any animal products at all). Avoid dairy, processed food, stimulants like caffeine, and artificial flavorings and other chemicals.

12. How often can I do a modified fast without slowing down my metabolism?

Modified fasting can be done up to weekly without fear of lowering your metabolism . 4 For those with significant health challenges or who have a lot of weight to lose, you can safely fast once per week (meaning three days out of every seven). Our ancestors were incredibly familiar with food scarcity, and most humans around the globe, until about 100 years ago, had long periods of time with only one or two meals per day. (In fact, as strange as this may seem to North Americans, many indigenous cultures around the world currently eat one or two meals a day.) Our bodies know just how to take advantage of those conditions! While modern society offers us food 24-7, making the choice to fast regularly is one of the smartest things you can do for your health.

13. Is there anyone who shouldn’t do a modified fast?

The great thing about a modified fast of three days is that it’s accessible for a lot of people for whom fasting generally isn’t a great option, including older adults. Water fasting isn’t recommended during pregnancy or the first few months of exclusive breastfeeding, or for people who have an eating disorder, hypertension, diabetes, kidney disease, or heart disease. People in cachexia (muscle wasting) from stage IV cancer should consult their physician, but even modified fasting is usually contra-indicated in this situation. When in doubt, talk with your trusted functional medicine doctor about whether a modified fast is right for you.

14. Should I be worried about muscle loss during modified fasting?

No! It’s a common myth that the body will start metabolizing muscle as soon as you enter a fasted state. You’d have to fast for quite a long time for that to happen. During a fast, your body will use up your fat stores 4 (that’s a big reason they exist, to get you through a famine!) and break down damaged bits of protein and cells for fuel (autophagy). During a modified fast, you’ll also be eating enough protein and micronutrients to maintain muscle tissue. [caption id="attachment_126039" align="aligncenter" width="300"] Your fat stores get used up while fasting, not muscle. In fact, our protein powders help your muscles keep building![/caption]

15. Are there any challenges I should prepare for?

Many people experience something called “Herxheimer reactions ” during a fast, as toxins that have been tucked away in your fat tissue flood through your organs on their way out of your body. You might experience headaches, digestive issues, or other brief symptoms. Know that this is normal, and actually, it's a good sign of how much your body needed to detox. Keep drinking water to help flush these toxins out, and consider a coffee enema to help speed up the process.

16. What kind of health benefits should I expect to see from modified fasting?

This is the most important question, and I’ve saved it for last because it deserves its own section, up next! Here's the short version when it comes to the health benefits of modified fasting: allows your body to burn abdominal fat stores for weight loss recycles damaged cells triggers cellular regeneration triggers human growth hormone and stem cell production boosts the immune system improves memory and cognition slows bone loss increases life span fights tumor growth reverses fatty liver syndrome decreases overall cholesterol and blood pressure decreases overall inflammation balances the hormone (endocrine) system regenerates the myelin sheath, preventing Multiple Sclerosis, Alzheimers, Parkinson’s, etc. breaks down cancerous growths helps reverse metabolic syndrome . . . and the list goes on!

What is a green smoothie made of?

Green smoothies are simply blended mixtures of whole foods that include greens (like spinach, kale, and collard) or other nutrient-dense veggies, and they may or may not contain other ingredients like fruit or nuts blended in. Don’t let the name mislead you—green smoothies don’t necessarily come out looking green! Some of my smoothies do have a rich green hue, but I’ll often add frozen mixed berries to make them purple or other ingredients that turn the smoothie purple, pink, or orange.

Are green smoothies really that healthy?

Green smoothies are very healthy, especially if the emphasis is on the greens! Green food is a powerhouse of enzymes, vitamins, minerals, and fiber. Drinking a quart of green smoothie a day addresses what I believe is the #1 deficit in the American diet: lack of leafy greens. A close second deficit is lack of overall plant fiber in the diet, but eating green smoothies addresses that, too. One quart of green smoothie per day can be a major game-changer for your health. Based on my research poll of 175 adults for The Green Smoothies Diet , 95.4% of people who drank a daily quart of green smoothie for 30 days reported improved health or quality of life. Specifically, the quart-a-day health benefits respondents reported were: more energy (85%) improved digestion (79.5%) fewer cravings for sweets and processed foods (65%) more positive, stable mood (54%) improvement in skin tone and clarity (50%) weight loss (50%) Green smoothies are “fast food” that actually leave you feeling energized. It’s easy to make one for yourself before you go to bed, put it in a glass jar and refrigerate overnight before drinking it in the morning on your way out the door, which is a vast improvement over most quick options or skipping breakfast entirely.

How long will a green smoothie keep in the fridge?

Green smoothies keep well 2 or 3 days in the fridge. They often begin to separate fairly quickly, but that is easily remedied by a quick shake or another spin in the blender. After the third day, though, you’ll notice your green smoothie start to taste a little off.

Can green smoothies be frozen?

You can freeze green smoothies! I like to pour them into pint-size jars (leaving a half inch or so space for expansion) and store them in the freezer. When ready to use, allow to thaw at room temperature or in the fridge, then shake well (or reblend) before drinking. You can also freeze smoothies in ice cube trays to re-blend later.

What blender should I use to make a green smoothie?

You can make a smoothie with any blender, but for proper digestion and the best benefit, the ingredients need to be blended thoroughly. Many blenders will give you “chunkies” to drink instead of smoothies, so I like a high-speed blender like Blendtec or Vitamix . I have a lot to say about the best blenders for making your green smoothies , but you can get a pretty good result with a cheaper blender if you don’t use frozen fruits or veggies and make sure to blend in ingredients a bit at a time. Make sure the mixture is a smooth puree before adding in the next ingredient. Add a bit more water if you feel the smoothie is too thick. I even have a reader who makes all her smoothies with her hand-held stick blender ! It’s great for making smoothies on the road, at work, and even at home.

Do green smoothies taste good?

The taste of green smoothies can certainly be an adjustment if you’re used to processed foods, but luckily, you can tailor the ingredients to your liking. Many folks start with a lot of mixed berries and other fruits in their green smoothies so the final result is sweet. Some also add a few drops of liquid stevia or a tablespoon of honey to make it even sweeter. Over time, as your preferences evolve, you’ll probably add more greens and still love the taste as much as ever.

What are the best greens for smoothies?

Pretty much any kind of edible leafy green can be thrown into your blender and whipped up into a tasty green smoothie. Spinach is very mild and a great green to start with (especially for kids’ green smoothies ). Other mild greens are kale, collards, and chard. Greens that are more savory or bitter can be added as you widen your repertoire, like beet greens, mustard greens, turnip greens, and arugula. There are even edible weeds you can use for smoothie greens, like dandelion and purslane.

How much does a green smoothie cost to make?

While the exact cost of a green smoothie will depend on your preferred ingredients, you’ll spend about 12 cents per ounce of green smoothie if you make it with about half greens and half fruit. That makes a quart of green smoothie cost about $3.76. Some cost variables include which ingredients you choose and whether you grow or forage ingredients, use in-season fruits and vegetables , or purchase organic produce . You may even be able to get some ingredients for free if you forage or know what to ask for at a farmer’s market.

How many calories are in a green smoothie?

The exact number of calories in a green smoothie depends on what ingredients you use, but a quart of green smoothie with about half greens and half fruit will be around 250 calories . 250 nutrient-dense, delicious calories!

What should I put in a green smoothie?

With the wide variety of fruits, vegetables, seeds, legumes, and other nourishing foods available, your green smoothie ingredient options are practically endless. Here are just a few possibilities: Liquid base: water, coconut milk, coconut water, almond milk, juice Leafy greens: spinach, kale, chard, collard greens, beet greens, mustard greens, sprouts, bok choy Vegetables: celery, beets, cucumbers, sweet peppers, sweet potato, broccoli, cauliflower, zucchini, purple cabbage, carrots Fruit: bananas, mangos, berries, lemon, apricots, watermelon, pomegranate, oranges, apples, cantaloupe, peaches, grapes, pears, dates, limes, plums, pineapples Healthy fats: avocado, nuts, nut butters, coconut oil, sprouted ground flax, flaxseed oil, sunflower seeds Extras: cacao powder, cinnamon, bee pollen, parsley, maca, real maple syrup, honey, fennel, turmeric, basil, cilantro, aloe vera, protein powder, vanilla extract

Should I buy organic ingredients for green smoothies?

It’s not necessary to buy all-organic produce for green smoothies, especially for foods that have thick outer shells or peels that are removed, like watermelon, bananas, oranges, lemons, limes, and pumpkins. But you may want to consider organic for other produce that is more difficult to wash herbicides and pesticides from, like leafy greens (spinach, kale, collards) and strawberries. Check out our more complete discussion of what “organic” actually means , plus a list of which foods you should buy organic and which ones are okay to get conventionally.