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. <img aria-describedby="caption-attachment-126039" class="size-medium wp-image-126039" src="https://greensmoothiegirl.com/wp-content/uploads/2019/09/flash-fast-chocolate-being-stirred-300x170.jpg" alt="Photo of woman stirring GreenSmoothieGirl chocolate plant protein powder into glass of water from "Modified Fasting 101: The Ultimate Beginner’s Guide" by Green Smoothie Girl" width="300" height="170" /> Your fat stores get used up while fasting, not muscle. In fact, our protein powders help your muscles keep building!

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!