My thoughts on Intermittent Fasting

[foodandfitness]

I've been reading a lot about IF on the forums lately. From what I've read I'm not really sure why frequent feeding or IF would have any real impact on bodybuilding as long as you ate the same amount of calories. So here are the conclusions that I've drawn after doing some thinking and doing a little bit of research. I'll start with a background on fasting, glucose and insulin, and then talk about the practicality of both methods and some research on meals and timing.

In normal metabolism, there are five stages in which the body utilizes nutrients. Phase 1 is the normal fed state where a majority of glucose comes directly from a food source. Phase 2 is a post absorptive state in which blood glucose originates from glycogen breakdown and hepatic gluconeogenesis. In phase 3, early starvation- lactate, alanine, and lyceral are also substrates for gluconeogenesis. Phase 4 is preliminary prolonged starvation in which the brain begins to use keytone bodies for energy after 60 hours of starvation. Phase 5, which is secondary prolonged starvation, hepatic and renal gluconeogenesis supply blood glucose and the rate of glucose used by the brain is diminished.

Since glucose is the preferred source of energy by the brain and almost all cells in the body and most of us are not going to fast long enough to enter ketosis, let us assume that intermittent fasting will be long enough for the majority of glucose used for energy is coming from liver glycogen and conversion of fats and proteins into glucose.

The two primary hormones responsible for regulation of blood glucose levels are insulin and glucagon. Insulin promotes energy storage (anabolism) and glucagon promotes energy production (catabolism). Insulin also inhibits glycogenolysis and gluconeogenesis. A healthy person secretes 0.5 to 0.7 units of insulin per kg per day. When blood glucose is low, glucagon is released by the pancreas to promote glycogenolysis, gluconeogenesis (protein breakdown), and lipid breakdown. Epinephrine, norepinephrine, growth hormone and cortisol are other hormones that have an antagonistic effect on insulin. Glucagon-like-peptide-1 and amylin to help regulate glucose.

Based on the clinical practice guidelines of the American Diabetes Association a fasting blood glucose level (performed after an overnight fast) is between 70-99 mg/dL. An oral glucose tolerance test is performed after an overnight fast. The subject is given a 75 gram pure glucose drink and blood is drawn 2 hours after. A normal level is less than 140 mg/dL. So just 2 hours after drinking pure glucose, the body brings serum glucose levels down to within 40 mg/dL of an overnight fast. Hmmm… It seems that glucose homeostasis is quite desirable for the body and whether or not we are eating or fasting its going to come from food or glucagon is going to get it into the blood if we are fasting.

Insulin is the master anabolic hormone. Yes, even before testosterone and GH and what have you. You can take all the steroids in the world but you won’t grow a pound if you don’t eat enough and make enough glucose and insulin to drive protein synthesis in the muscle cell. As stated above, the presence of insulin prevents gluconeogenesis (using protein to make glucose). Anabolism occurs when insulin allows glucose to enter the muscle cell which drives cellular metabolism and therefore protein synthesis. Do all glucose and insulin responses result in anabolism or positive energy balance? No. These nutrients must come from glucose derived from food because glucose pulled from the liver or converted out of fats or proteins do not yield a net gain of energy, and therefore an overall anabolic response. When glycogen, fats, and proteins are shifted and converted from one form to another, this takes metabolic work. Inefficiencies in this metabolic work (no reaction is 100% efficient) are released as heat and energy is lost. Catabolism is occurring.

When you are not fasting, glucose is present in the bloodstream as a result of digestion. Insulin is rapidly pulling glucose into the muscle cells to be used for metabolism.

When you are fasting, glucose is still present in the bloodstream as a result of homeostasis from glucagon and insulin hormone responses. The brain’s primary source of energy is glucose. So you can be damn sure that your body makes certain the brain gets what it wants in sufficient amounts. The only difference is that, as stated above, fuel sources are simply being moved around and energy (and nutrients) is being used up in the process.

What does this mean? Should I eat constantly to promote anabolism? Not necessarily. Let’s look at this in 3 scenarios and assume you need 4000 Calories a day to gain weight with all the muscle mass you have and all the exercise you are doing:

1. You eat often, 4000 Calories in 6 small meals a day. In this scenario food is eaten in small to medium amounts. You are not uncomfortably full and food moves through the GI tract in smaller amounts and provides a relatively constant supply of glucose and nutrients into the blood stream. Your energy levels could be represented as a sine wave with small yet frequent peaks and valleys on a graph. Insulin is released. Anabolism occurs.
2. You eat less often, 4000 Calories in 2 or 3 big meals. In this scenario food is eaten in larger amounts. You may be uncomfortably full depending on how you handle big meals. Food sits in the stomach a bit longer but still moves through the GI tract between meals. You are provided with a relatively constant supply of glucose and nutrients. Insulin is released. You may have a short period where liver glycogen is utilized to release glucose into the blood. Problem? Nope. Anabolism occurs. You ate 4000 Calories today and are in positive energy balance.
3. You eat one big 4000 Calorie meal. In this scenario you are, in my opinion, an idiot. You are a glutton for punishment. For some reason you like feeling ridiculously full and obviously have no laborious tasks to perform for some time after your meal. But still, you ate 4000 Calories. Your glucose and energy levels look more like a bell curve compared to the sine wave responses from 1 and 2. 4000 Calories is 4000 Calories. Positive energy balance. Anabolism.

Looking at these 3 scenarios in a practical sense we can infer that eating all of your calories in one meal is difficult at best. However, as you desire more and more growth, your caloric intake must also increase. Eating all your calories in 2-3 meals becomes less and less feasible. If all of these scenarios result in anabolism, I would suggest choosing the one that makes you feel the least uncomfortable for the sake of compliance.

Ok, so all of this stuff is primarily looking at insulin response and anabolism related to positive energy balance. I have described how whether in a fasted or fed state, the body will regulate blood glucose to make sure there is a constant supply of fuel to drive metabolism. Now let’s look at some research. Note that these studies may not necessarily be examining bodybuilder subjects. Why? There is more money in healthcare research. Most of the sports nutrition science we have today started off in a clinical setting. Did you know L-arginine and HMB were initially used to enhance wound healing and prevent catabolism in hospital burn units? But I digress… Here are some articles that look at the relationship between nutrition and timing. Because that’s the basic theory of IF, Warrior Diet, etc. right? We are manipulating nutrient timing to get some sort of positive benefit whether that be increased size, strength, improved energy, etc.

http://www.ncbi.nlm.nih.gov/pubmed/21123467
“The Effect of Eating Frequency on Appetite Control and Food Intake: Brief Synopsis of Controlled Feeding Studies”
- People ate at different frequencies. 1 meal a day to 4 or more meals a day.
- Eating more than 3 meals a day didn’t seem to improve appetite control significantly
- Eating less than 3 days negatively affects appetite control

http://jp.physoc.org/content/535/1/301.full

“Timing of postexercise protein intake is important for muscle hypertrophy with resistance training in elderly humans”
- Old people lifted weights
- One group got protein immediately after lifting and one group 2 hours after lifting
- Old people who consumed protein immediately after had more significant improvements in strength and size

http://journals.lww.com/acsm-msse/Ab...istance.6.aspx

“Effects of Supplement Timing and Resistance Exercise on Skeletal Muscle Hypertrophy”
- Experienced male weight lifters lifted weights
- One group received protein, carbs, and creatine pre and post workout while the other group got the same supplement in the morning and evening
- The group that got their supplement pre and post workout got bigger and stronger than the group that ate their supplement morning and evening

http://onlinelibrary.wiley.com/doi/1...247.x/abstract

“New approach for weight reduction by a combination of diet, light resistance exercise and the timing of ingesting a protein supplement”
- Fat guys lifted weights
- One group received a protein drink post workout the other did not. However, calorie and protein amounts for the day were same in both groups.
- Fat guys that lifted weights and drank a protein shake post workout

For the rest of these articles I’ll just list the link and a brief statement.

http://www.ncbi.nlm.nih.gov/pubmed/11440894
- protein immediately before lifting weights increases protein synthesis more than after

http://www.ncbi.nlm.nih.gov/pubmed/15570142
- protein before exercise can increase protein synthesis

http://www.ncbi.nlm.nih.gov/pubmed/18284676
- nutrient timing had no effect on controlling muscle damage from exercise

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2575187/
International Society of Sports Nutrition position stand: Nutrient timing
- this is a great read and contains some of the links above plus many more.

My thoughts of IF versus frequent eating are this. Don’t train hungry but don’t train when you are stuffed either. Lifting in a fasted state may or may not be SLIGHTLY beneficial to lifting in a fed state. From my personal experience, I concentrate better when I am moderately fed and therefore can focus on my lifts. I don’t get as sleepy after lunch when I eat a mid-morning snack. There are ideal scenarios and then there is real life. If I have to miss a meal to take care of something I’m going to feel better if I just at 2 hours ago than if I’ve only eaten once that day. What if I go to a party, to a friend’s house, or to a restaurant to eat and the meal isn’t that nutritious? I don’t want half of my daily calories to have to come from that meal because I only eat twice a day. I don’t necessarily only use my anaerobic pathways when I lift weights. High volume can keep my heart rate up and sometimes I like to go for a run. Performing cardiovascular exercise in a fasted state is difficult.

In conclusion, more research needs to be done to make a conclusion about fasting versus frequent feeding. Based on what I’ve learned so far I have to make a conservative recommendation and say that it really doesn’t matter how often you eat as long as you feel comfortable with your method. I would recommend making sure you have some food in your system before you lift weights whether that happens from a small pre workout shake or just eating a big meal plenty of time ahead of your workout. Is eating 6 small meals a day broscience? If you are doing so with the hopes to rev up your metabolism, then yes. If you have a high caloric demand for growth, then spreading out your food throughout the day is a practical and simple solution to just getting in enough calories.

Your thoughts?

[AlwaysTryin]

Insulin also inhibits glycogenolysis and gluconeogenesis.

When blood glucose is low, glucagon is released by the pancreas to promote glycogenolysis, gluconeogenesis (protein breakdown),

Interesting reading.

The bolded part, protein breakdown comes from the Glucose-Alanine cycle through muscles, gluconeogensis isn't protein breakdown, it's using pyruvate/lactate etc.

Also you forgot the other inhibitors like the FBiPase's/PFK's etc

Other than that a very good effort into an informative post!

[spicyprice]

I read Eat Stop Eat by Brad Pilon and found the long term benefits of remaining in a fasted state for longer periods of time interesting. Its def worth reading.


Edit: I do not in any way have any substantial knowledge of human nutrition, but found the book easy to read. Definitely does not go into the depth of what you know regarding the physiology of it.

[YeomenKek]

Great read, thanks OP and repped. I agree 6 meals vs IF benefits/drawbacks are slight if any at all, and I've come to accept the only reason I eat 2-3 big meals a day is because I find it suits my lifestyle better.

Thanks for the refs.

[foodandfitness]

Interesting reading.

The bolded part, protein breakdown comes from the Glucose-Alanine cycle through muscles, gluconeogensis isn't protein breakdown, it's using pyruvate/lactate etc.

Other than that a very good effort into an informative post!

You know, I looked at that for a while too and thought I might be oversimplifying it. I thought the transamination of proteins into pyruvate to enter the TCA cycle occurred in muscle cells too. Thanks tho, I obviously need to look that up!

[DanTheManB]

#1 It depends on what you consider "IF" to be....an 8 hour eating window is not IF in my book. I don't give a fuk.

#2 Whether or not said IF is best depends on the person's individual GOALS for training+nutrition. Also throw in work/school schedule.

This whole topic is a waste of time.

IF you want to be a successful bodybuilder or athlete 9 out 10 will need to constantly supply the body with fuel.

If you want to be a year round 7-8% BF kinda guy with a good build then by all means eat two meals/day.

[foodandfitness]

This whole topic is a waste of time.

Indeed it is. Thanks for reading and posting on this thread about IF and all the other threads about IF you've been reading and posting on so much lately. Big waste of time.

I agree with your seemingly angry attestations about IF. I'm on here to talk about some science. You mad, bro?

[DanTheManB]

Indeed it is. Thanks for reading and posting on this thread about IF and all the other threads about IF you've been reading and posting on so much lately. Big waste of time.

I agree with your seemingly angry attestations about IF. I'm on here to talk about some science. You mad, bro?

I'm not mad at all. Real life experiences trump science experiments BRO

[dustinh6719]

#1 It depends on what you consider "IF" to be....an 8 hour eating window is not IF in my book. I don't give a fuk.

Not here to argue or anything, but if you don't consider an 8 hour eating window IF, then what do you consider IF?

[DanTheManB]

Not here to argue or anything, but if you don't consider an 8 hour eating window IF, then what do you consider IF?

apparently the clinical definition is one day of feeding and the next fasting and so on

for myself I consider it either the warrior diet or 2 meals/day one in the AM, one in the PM

[dustinh6719]

apparently the clinical definition is one day of feeding and the next fasting and so on

for myself I consider it either the warrior diet or 2 meals/day one in the AM, one in the PM

Ah, gotcha. Now your arguments make sense

[foodandfitness]

I'm not mad at all. Real life experiences trump science experiments BRO

Agreed.

Say, Dan. What kind of workout routine are you doing, Anything along the lines of periodization? You know, Bro. Muscle confusion? Maybe going through cycles of low repetitions to focus on strength and higher repetitions for hypertrophy? Nice, neat little concepts that came from sciences experiments before you were born. Maybe saved you some time than figuring it all out on your own.

Science experiments are real life experiments from other people, Bro. They just get written down in journals. There are different levels of validity, not all experiments are double blind placebo studies. Expert opinions, like yours, and case studies are also used to draw conclusions so people can make educated guesses as to how they should start those real life experiences of their own.

[DanTheManB]

Agreed.

Say, Dan. What kind of workout routine are you doing, Anything along the lines of periodization? You know, Bro. Muscle confusion? Maybe going through cycles of low repetitions to focus on strength and higher repetitions for hypertrophy? Nice, neat little concepts that came from sciences experiments before you were born. Maybe saved you some time than figuring it all out on your own.

Science experiments are real life experiments from other people, Bro. They just get written down in journals. There are different levels of validity, not all experiments are double blind placebo studies. Expert opinions, like yours, and case studies are also used to draw conclusions so people can make educated guesses as to how they should start those real life experiences of their own.

Actually I don't train like that. I don't follow any particular split as I hit whatever I feel like and mix body parts...my workouts also consist of dropsets, 3 rep sets, 15+ rep sets, 8-12 rep sets etc etc

again I go by feel and my past experiences with myself.

glad you know everything about me tho

[DanTheManB]

Actually I don't train like that. I don't follow any particular split as I hit whatever I feel like and mix body parts...my workouts also consist of dropsets, 3 rep sets, 15+ rep sets, 8-12 rep sets etc etc

again I go by feel and my past experiences with myself.

glad you know everything about me tho

strong ownage of your assumptions with no reply

[MikeK46]

I agree that meal timing doesn't seem to matter much from a nutritional point of view, and that one should eat as many meals as their stomach feels comfortable with.

However, I must also add that nutrition is just one of three inter-related requirements. The other two are training and rest.

Because all three are necessary to achieve the best results, your nutrition must support the highest possible performance in the other two areas.

To put it simply, one should also eat in a way that allows them to train with highest intensity, recover quickly, and have a good nights sleep. If you are unable to lift as heavy and get fatigued quicker when training fasted, then you will not get the best results. If you experience prolonged fatigue when not eating for many hours post-workout, then you will not get the best results. If you are unable to sleep well on a full or empty stomach, then you will not get the best results.

I feel that, while meal timing has no direct influence on results, people often forget the indirect relationships between nutrition and results.

[ErickStevens]

Inb4shiitstorm...

Oops. Too late.

[DanTheManB]

Inb4shiitstorm...

Oops. Too late.

ultimate trolling 101