Why Fasting
Why I Like Intermittent Fasting:
1. It helps lose weight
2. It helps maintain target weight
3. It’s simple to execute
4. It helps improve performance
5. It helps lower the triacylglycerol concentration in the body
6. It helps shorten recovery time by increasing the natural production of HGH
7. It helps improve memory and fight age-related illness
Caution
8. People with diabetes or any type of abnormal metabolic conditions MUST NOT attempt fasting
9. Fasting should only be applied after you are “dialed-in” with your nutritional plan, sleep pattern, and workout habits. Intermittent Fasting is no match against crappy lifestyle choices.
The Takeaway
The fasting strategy is all-purpose, i.e. for sports performance, weight reduction, and lifestyle. Intermittent Fasting (IF) adds numerous health benefits and does not require a lot of effort. Even those who want to gain weight should experiment with it; just use it a lot less frequently.
The same strategy will apply to all body types and to both genders. As long as you don’t have any metabolic conditions such as diabetes, the fasting strategy I gave you will work the same via the same metabolic mechanism.
Now, for the biochem geeks who want to know in detail how our bodies respond to fasting, here is the long version of the blog (reading time approx. 25 minutes)…
Last week, when I was the ‘human target’ in our sparring session, my weight was around 177 lbs. As most of you know, I normally walk around at 190+ lbs. I dropped the weight to help increase my stamina and to be faster, so I can better keep up with Speedy Gonzales (aka Sal!). The lighter weight did its job on stamina, but didn’t make any difference in running away from you-know-who (Sal). So I’m going to bring my weight back up again.
How did I drop the weight?
Intermittent Fasting, IF.
The most proven method to lose weight is to restrict calories. The studies indicate that the benefits of calorie restriction include improved memory [1], delayed physiological aging [2], and combating age‑related illness [3]. And one of the best ways to restrict calories is to use intermittent fasting.
The popular advice [4,5] in men’s magazines and numerous diet books is that eating 6 small meals a day is the best way to lose weight. So if it is popular then it must be true, right?
Not so fast.
These are the main arguments for the 6-meals-a-day plan:
- It boosts resting metabolic rate via the thermic effect of food
- It increases energy
- It decreases appetite
While most of us would agree that eating more often decreases appetite, there is hardly anything out there that comes close to the consensus on the claims of improvement in the resting metabolic rate or an increase in energy [6].
Exercise is the only consistent way to elevate the resting metabolic rate [6,7,8].
Surprised?
Two reasons why I might recommend the 6-meals-a-day approach to a client:
- If the client is a body builder or wants to gain weight;
- If the client has bad eating habits. (randomly skipping meals is NOT fasting, by the way)
Here are the disadvantages of the 6-meals-a-day approach:
d1: It’s hard to follow on so many different levels.
d2: It lacks strong research data
d3: See d1
Why I like the Fasting Method…
- It’s much easier to execute. It’s ON or OFF. There is no guesswork. I don’t have to set my alarm every 2 hours, nor do I have to measure my food every time I eat. “Eyeballing” your portions is a guaranteed way to over eat. That is human nature. Athletic training centers or the personal chefs for pro-athletes measure and weigh every raw material that goes into each meal for that very reason: humans are notoriously bad at guesstimating.
- The benefits of fasting can easily be explained by metabolism.
- It helps induce natural HGH production in the body, from 1.9µg/L to 11.0 µg/L after 60 hours of fasting [10].
- It helps lower triacylglycerol concentration. High triacylglycerol in the bloodstream is linked to thickening of artery walls and increased risk of heart disease and stroke [15].
- There are many supporting scientific research studies [9,10,11,12,13,15].
How Does Fasting Work In Weight Reduction?
After we finish a meal, glucose and amino acids are absorbed by the small intestine into the blood, triggering the secretion of insulin. This high insulin level soon after a meal promotes the uptake of amino acids by the muscles and stimulates protein synthesis, but it also promotes fatty acids production in adipose tissue (body fat).
Several hours after the meal, the blood glucose level starts to drop, resulting in decreased secretion of insulin. When the fasting is prolonged to the point that our body’s carbohydrate reserves are exhausted, the metabolic process changes, shifting from glucose as the primary fuel to fatty acids – via gluconeogenesis by the liver.
During fasting, our body gets energy by oxidizing fatty acids released from adipose tissue. Muscle shifts almost entirely from glucose to fatty acids for fuel.
Doesn’t Fasting Trigger Starvation AND Slow Down Metabolism?
Technically, yes but the number is negligible. After fasting for 60 hours, our resting metabolism rate slows down by 28 calories per day (that’s roughly equal to 3 mentos per day, a really tiny drop) [10].
But the return is tremendous. During fasting, our fat metabolism increases by a factor of 2.5, jumping from 46 cal/hr to 115 cal/hr [10].
Therefore at the normal fat burn rate of 46 cal/hr, it would take approximately 3 days to get rid of 1 lb (3500 cal) of body fat. But in the fasting state, where the fat burn rate is 115 cal/hr, it’ll only take 1 day and 6 hrs to metabolize the same amount of fat.
Wanna lean out? Go Fast!
Will Fasting Trigger Muscle Loss?
Yes, you’ll lose some muscle, but only a little, because our bodies want to preserve muscle. Muscle loss is probably the worst nightmare for body builders and that’s why they prefer the 6-meals-method. Knowing how sensitive body builders are about their lean body mass, mentioning any muscle losses – regardless of whether it is real or imaginary – will trigger some kind of anxiety attack with those boyz.
In the wild, animals depend on being able to move rapidly to enhance their survival chances. This requires a large muscle mass, so muscle loss must be minimized. Our metabolism is designed to meet that requirement.
Here is how:
After most of your glucose is used up and the glycogen in the liver is depleted, the liver forms large amounts of acetoacetate and d-3-hydroxybutyrate (ketone bodies) from acetyl CoA, because the Krebs cycle is unable to process all the acetyl units produced by oxidizing of fatty acids. So acetyl CoA is blocked from entering the Krebs Cycle by reducing oxaloacetate (the key compound for acetyl CoA to enter into the Krebs cycle). This forces the brain (and heart) to start using ketone bodies (generated from the triglycerides pathway) as fuel instead of glucose. Once the brain is accustomed to using ketone bodies as the major energy source instead of glucose, the metabolism will switch to the triglycerides pathway, using fat as the main source of fuel.
Acetoactate is activated by converting succinyl CoA to acetoacetyl CoA. The enzyme thiolase then converts acetoacetyl CoA back to acetyl CoA, which enter the Krebs cycle as fuel [13].
The effective conversion of fatty acids into ketone bodies and their use by the brain (and heart) markedly protect the muscle from proteolysis (protein breakdown).
Do Not Skip Meals Randomly!
The break down of 20 g/day of muscle during fasting compared with 75 g/day when you just skip meals is one of the main differences between fasting and starving yourself when you feel like it (aka the bulimic diet). When you skip a meal while your body is still in glycolysis mode, your body will go after any glucose in your body. The result of depletion of the liver’s glycogen means the activation of gluconeogenesis, but at this stage, this process merely replaces glucose that has already been converted into lactate and alanine by the peripheral tissues. Moreover, the brain oxidizes glucose completely to CO2 and H2O. Thus, for the net synthesis of glucose to occur, another source of carbon is required. Glycerol released from adipose tissue on lipolysis provides some of the carbons, with the remaining carbons coming from the hydrolysis of muscle proteins [13].
Off On A Tangent:
What happens when your body fat deposits are completely gone, when fasting has gone too long, and the only source of fuel that remains is proteins? This will force the metabolic process to accelerate the protein break down, starting with the internal organs’ muscle, and death inevitably results from a loss of heart, liver, or kidney function.
A typical well-nourished 154 lb American has fuel reserves totaling about 161,000 calories. The energy needed for a 24-hour period ranges from about 1600 cal to 6000 cal, depending on the extent of activity. Thus, stored fuels suffice to meet caloric needs in starvation for 1 to 3 months.
Does Fasting Elevate Cortisol Levels?
Yes, but again not very much. Fasting 12 to 60 hours raises the cortisol level (“the stress hormone”) from 339 nmol/L to 412 nmol/L [10]. In comparison, lack of sleep will put you in the 636 nmol/L level or higher Range [14].
Key Point
Here is the optimum order of implementation: (1) establish good eating habits, (2) develop a solid sleep pattern, plus (3) EP-fit, then (4) play with IF. Intermittent Fasting is no match against a crappy lifestyle, according to Robb Wolf, the Crossfit nutrition guru.
Traps
You need to stay on an eating schedule as close to the plan as possible. Our metabolism is highly adaptable, but we need to train it so it will do what we want it to do. Do not skip meals randomly and think that is fasting – it is NOT, and you’ll suffer for no reason.
Do not over-stuff yourself at the first meal immediately after each fasting period. Some over-eating is expected, but if you eat near double the calories prescribed, you’ll just hurt later. It’s better to keep your calorie count as consistent as possible for all your meals (and this will make your next intermittent fasting period easier).
The first couple of times you fast, it’s quite possible that it may cause you some difficulty sleeping. But don’t give up. Have a couple glasses of warm water to ease the discomfort, relax, and go back to sleep.
The hunger feeling is very manageable, because true starvation will require you to fast for weeks. In 24 hours, our metabolism is still in a “fed” state. To completely alter our metabolic pathway to using triglycerides usually requires at least 60 hours of fasting. We just use the multiple intermittent fasts to trick our metabolism into thinking we have fasted for more than 60 hours. The headaches, tummy aches, and other ‘hunger’ cues comes from the body having been conditioned to eat every few hours. These hunger cues are just learned behavior, and one can unlearn it. After a few fasting intervals, the hunger cues will go away naturally on their own [16].
Caution
People with diabetes MUST NOT attempt fasting. A diabetic’s metabolism is different and requires a different strategy for weight management.
The Takeaway
Want to lean out? Let intermittent fasting become part of your lifestyle. The benefits are many, and it doesn’t take much to get used to it. Many weekend warriors, boxers, wrestlers, dancers, and metros have mastered this simple art of caloric restriction. Give it a try; the results may surprise you.
References
1. Caloric restriction improves memory in elderly humans
Department of Neurology, University of Münster, Albert-Schweitzer-Strasse 33, 48129 Münster, Germany (received for review September 4, 2008)
http://www.pnas.org/content/106/4/1255.full
2. Caloric Restriction and Delayed Biological Aging in Humans
School of Biological Sciences, University of Aberdeen, Aberdeen AB24 2TZ, Scotland, UK from American Society for Nutrition J. Nutr. 137:1078-1086, April 2007
http://jn.nutrition.org/cgi/content/full/137/4/1078
3. Reduced diet thwarts aging, disease in monkeys
Board of Regents of the University of Wisconsin System
http://www.news.wisc.edu/16889
4. Eat 6 Meals a Day for Maximum Weight Loss
Kim Roach is the Fitness Reporter at HealthyEveryDay.com, where you will find healthy diet recipes, fitness articles, and information
http://www.buzzle.com/articles/eat-6-meals-daymaximum-weight-loss.html
5. Healthy Dieting: Eat 5 Meals a Day and Lose Weight!
http://www.buzzle.com/articles/healthy-dieting-eat-meals-lose-weight.html
6. 3-Hour Diet or 3 Meals a Day?
By Elaine Magee, MPH, RD, LD WebMD Weight Loss Clinic – Feature
http://www.medicinenet.com/script/main/art.asp?articlekey=56254
7. Basal Metabolic Rate (BMR)
http://en.wikipedia.org/wiki/Basal_metabolic_rate
8. Attenuation of age-related changes in mouse neuromuscular synapses by caloric restriction and exercise
Department of Molecular and Cellular Biology and Center for Brain Science, Harvard University, Cambridge, MA and Laboratory of Genetics, The Salk Institute for Biological Studies, La Jolla, CA
February 20, 2010, http://www.pnas.org/content/early/2010/07/26/1002220107.abstract
9. Intermittent fasting dissociates beneficial effects of dietary restriction on glucose metabolism and neuronal resistance to injury from calorie intake
Laboratory of Neurosciences, Gerontology Research Center, National Institute on Aging, 5600 Nathan Shock Drive, Baltimore, MD
http://www.pnas.org/content/100/10/6216.full
10. Fuel and energy metabolism in fasting humans
Am J Clin Nutr 1994;60:29-36. © 1994 American Society for Clinical Nutrition
http://www.ajcn.org/cgi/reprint/60/1/29.pdf
11. Fasting, lipid metabolism, and triiodothyronine in rat gastrocnemius muscle: interrelated roles of uncoupling protein 3, mitochondrial thioesterase, and coenzyme
Journal Online by The Federation of American Societies for Experimental Biology.
http://www.fasebj.org/cgi/content/abstract/02-0839fjev1
12. Plasma Acetone Metabolism in the Fasting Human
The American Society for Clinical Investigation, Inc. 0021-9738/79/04/0619/08 Volume 63 April 1979 619-626
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC371996/pdf/jcinvest00676-0075.pdf
13. Food Intake and Starvation Induce Metabolic Changes
The National Center for Biotechnology Information, NCBI, The Integration of Metabolism
http://www.ncbi.nlm.nih.gov/bookshelf/br.fcgi?book=stryer&part=A4355
14. Cortisol in Blood
WebMD Author: Caroline Rea, RN, BS, MS; Specialist Medical Reviewer Alan C. Dalkin, MD – Endocrinology
http://www.webmd.com/a-to-z-guides/cortisol-14668?page=2
15. Alternate-day fasting and chronic disease prevention: a review of human and animal trials
American Journal of Clinical Nutrition, Vol. 86, No. 1, 7-13, July 2007
http://www.ajcn.org/cgi/content/full/86/1/7
16. Fasting for Weight Loss, Increased Human Growth Hormone, Immunity, and Longevity. The Intermittent Fasting Lifestyle
Chris LeCron, Associated Content, November 01, 2009
