There's a wonderful blog called The IF Life: Intermittent Fasting and Instant Freedom. It is written by personal trainer (and apparently former corporate bigshot), Mike O'Donnell.
Mike has a great take on brief, intermittent fasting that I found helpful and I believe you will also.
Intermitent Fasting 101: How to Start, Part I
The biggest question people have is how to effectively use IF (intermittent fasting) to achieve their goals and maximum results. These results and goals can vary by each person with fat loss, muscle gain, better health, improved performance in your sport of choice and more. With that comes the individuality of what is a person’s insulin resistance, current body composition (bodyfat%), daily lifestyle, eating habits, macronutrient ratios (carbs/protein/fat), type of exercise program, frequency and volume of training, recovery demands, and so forth. You are unlikely to find 2 people with the same set of parameters and same exact responses to an IF protocol. What does this mean? Well just that we need to start with a basic IF program, and then learn how to monitor results and adjust as we go. Even down the road things will change as you will improve health, lower insulin resistance and maybe change performance and recovery needs. So nothing is ever just one set way. Life is dynamic (always changing and evolving) and so should be the way we see our own journey for health and fitness.
What is IF?
For those that may not be familiar to the term, intermittent fasting is just taking times of fast (no food) and working them into your lifestyle. This can be either daily or a couple times a week (will get into that more below). Benefits include improving insulin resistance (which you will hear alot about as being the #1 key marker in so many health factors including weight loss, muscle gain, performance, recovery, anti-ageing and disease prevention) and giving the body a chance to do some internal cleaning (or housework), which can lead to improved immune function and overall health. If you want to see studies of all the benefits of IF/CR, please the resources page.
How do I begin to IF?
Is there only one set way in which to do IF? No. I could easily come up with 10 different IF protocols based on 10 people’s individual’s needs, lifestyle, exercise, goal, macronutrient ratios, and so forth. We will keep it simple and give the 2 most frequent and basic options.
Daily Fasting: Typically done every day and only giving the person a smaller eating window in which to get their calories. (for example, a 18hr daily fast would mean someone would only eat every day between the hours of Noon and 6pm). You will see varying times from 15-19 hours for daily fasting.
Fasting 1-3x a week: This could also be called alternate day fasting/calorie restriction (for those doing it every other day). This is just fasting of usually longer periods 18-24 hours but only 1-3x a week. Many variations to play with here.
“But which one is better and how to I do it now if I want…….”. Whoa, slow down. I know many have questions but let’s still try to keep this simple for now and expand into more specifics later. So far many people have experimented with both types of IF and have seen great results. But you also have to take into account all the other variables such as what is the person eating in that window? Is is junk food? Is it low carb? How many times a week are they doing it? Are they overweight and wanting just fat loss? Are they lower bodyfat but looking for improved performance and health? How many times a week are they exercising? What kind are they doing and what intensity? The list can go on and on, but let’s start to analyze the 2 types of IF and let you decide which one best suits your lifestyle.
Daily Fasting (15-19 hours):
The Advantages are:
--simple eating strategies for every day
--even people that may not eat 100% clean foods can see weight loss due to the smaller window and lower calorie total per day
The Disadvantages are:
--Can possibly lower metabolism if calories are too low for too long (not what you want if your #1 goal is weight loss)
--Not getting enough food in the smaller window may also lead to muscle loss for more active people (not good)
Fasting 1-3x a week:
The advantages are:
--Allows a person to make sure they are getting enough calories on the non-fasting days, and then just keeps to a simple small feed window (if any) on the IF days.
--Simple thinking for people who do not have experience in how to eat clean to eat one day, and then eat in a smaller window the following day (alternate day fasting/CR). This can achieve fat loss for people who are mostly overweight and may not be too active. (of course don’t get me wrong, that eating healthy is our main goal but this can be a good step for some people to start their weight loss jounrey and learn how to make better choices as they go)
Disadvantages:
--Doesn’t force a person to make better choices with their food (as one could probably eat junk one day, and then fast the next and still lose weight). Not something we want long term because this is not going to improve your other health markers (diseases prevention, insulin resistance) like a good IF program on healthy foods.
Again I can’t say it enough, as there are so many variables to play with in an IF program. Some people may say “well it didn’t work for me” or “I didn’t gain any muscle”. Well unless I know everything about what you do for exercise daily, your total calories, when you eat and your macronutrient ratios (protein/carbs/fats), I can’t even begin to help. IF is a simple tool to start with, but you have to take full responsibility for your own health and progress and learn when it is not working and when to change things up! Like I said, if it is NOT working then stop IF and rethink your attack plan (or get a professional to coach you on it).
So to sum up, here are some examples of what you can play with:
Daily Fasting of 15-19 hours. I would highly suggest that if you do this make sure you are recovering from your exercise and start only Mon-Fri and give yourself the weekends to eat all day (hopefully with healthy choices of course)
Fast 1-2x a week to start if you have never done any fasting or do not know how to eat healthy and control your macronutrients. Start with 1-2 days a week with fasts of 18-20 hours (I wouldn’t start with 24 hr fasts to begin as most people can not handle the hunger cravings and in turn will just end up eating all the wrong foods when they do eat) and say eat only from say 1pm-6pm for example. Drink lots of water (add lemon, your liver will appreciate it! and it will help with the hunger). For example, fast Wed and Sun (or whatever days fit into your schedule)
Or you can do a mixed approach and fast every other day for a small eating window. For example eat all day Mon, only 12-6pm on Tues, all day Wed, 12-6pm on Thurs, etc. Start with bigger eating windows and make them smaller as you get used to fasting. This approach may work for people who have alot of weight to lose and can not (I should really say “will not” as everything is a choice!) eat 100% healthy for the moment. This approach may not work for more advanced people who have a high activity level unless you are getting a ton of health calories in that fasting window.
“So What Do I Eat on the Fasting Days?”
That’s the best part, you should be able to eat unlimited healthy foods (healthy proteins, fats, veggies, fruit, nuts…see Paleo Diet in the resources page). If you are eating more processed foods, breads and other high calorie intakes then you may have to monitor and control portions. Please know this is NOT about chronic calorie restriction or starving yourself. When I do weeks of eating 1-7pm, I am eating a ton of protein and veggies (complex carbs pwo also). I am hardly starving myself. I am not taking in 4000 cal a day however, so my daily average of say 2200-2500 cal is still low compared to the alternative. If you want to lose weight of course you will need a calorie deficit to pull the “stored energy” out of fat cells. That is the advantage to eating “Paleo”, you can’t over eat on protein, healthy fats, fruits (in moderation) and veggies. If you are making bad choices or starving yourself on IF, you may lose the effectiveness or slow progress. All goes back to the fact that if it is not working, then change something up! (there is always something that can be changed…and food choices is the #1 place to start!) I don’t count calories, and by eating natural foods that have been around for 100s of years….I don’t need to! (eating healthy natural foods will not only help you lose weight but also improve your health and lower your risks of diseases….so eating for health should always be the #1 goal in any program)
Hopefully this will give a good overview while trying to keep it simple. Remember it’s your journey to take, measure progress and adjust things that are not working. Start with one approach, and modify it. Who knows, your approach may change every couple months and that is ok. Life is always changing and so should your approach to health and fitness (as the body always responds better to change than sticking with the same eating/exercise approach for a long period of time).