INTERMITTENT FASTING
So you're looking to lose weight in the most simplest way possible? 🤔
No food logging required...
No Detoxes...
No giving up your favorite foods... (That's right, you can still eat your favorite foods!)
With Intermittent Fasting, there is really only one thing you need to do...
Sound too good to be true?
Read on as we revisit some of the science behind the popular diet method.
WHAT IS INTERMITTENT FASTING?
Intermittent Fasting is a popular feeding strategy for those whom want to lose weight without giving too much thought on the dieting process. Also known as 'delayed eating', Intermittent Fasting involves restricting calories early on in the day for a greater amount of calories later.
Traditionally IF requires an energy time restriction of 16 hours (fasting) with only an 8 hour window of time for food consumption.
Note: The amount of time one fasts can also vary depending on sleeping patterns generally ranging anywhere from 14-18 hours (fasting) and 6-8 hours for consumption.
In it's simplest form it acts as an umbrella of Intermittent Energy Restriction and gateway to various other dietary protocols and energy prescriptions including:
⚠️ 24hr restriction
⚠️ 5:2 fasting
⚠️ 7 x day energy reduction
⚠️ Continuous Energy restriction (CER)
Much like continuous Energy restriction (Calories In = Calories Out), Intermittent Fasting may or may not place heavy restrictions on food quantity and food types around a daily 24 hour schedule.
However like most diets with a premise of getting you results, there is always a 'gimme' and a 'gotcha'...
HOW DOES IT WORK?
One of the first things we are prone to do as the day begins is to start feeding. Also known as 'breaking the fast'- a meal eaten in the morning, the first of the day.
During our first meal we typically begin to load more nutrients into the body whilst simultaneously signalling to bypass and use up any remaining 'fuel' leftover in storage[6].
During this feeding period, it's not uncommon for a large majority of Nutrients consumed to be predominantly Carbohydrates based. Anything from:
⚠️Liquid shakes
⚠️Coffee + Milk + Marshmallows or a Hot Chocolate
⚠️Wholegrain Cereals
⚠️Toasties or Croissants
⚠️Fruit
⚠️Packaged Snacks etc.
Carbohydrates are very easily digestible and low in Satiety. Meaning we are more than likely to go back for more!
How many times do we find ourselves going back for multiple bowls of your favorite cereal? It's not uncommon for some individuals to consume entire boxes of cereals in one single sitting.
To put this into perspective that's over 1000 - 1200 Calories to start your day!
In today's current climate, various individuals undergo periods and bouts of yearly weight loss attempts to reduce their overall fat mass[24]. Whether if it's an athlete preparing for a bodybuilding show, a sedentary office worker or stay-at-home mum-preneur looking to re-wire poor lifestyle habits.
For most individuals however, failure to reach their target body weight in the days or weeks of undertaking a nutritional weight management strategy can often be quite disheartening.
Within the weight loss demograph, the most common nutritional weight loss strategy implemented is most often misunderstood[22]. As a result individuals may often seek alternate sub-optimal dietary strategies for more rapid weight loss techniques i.e. acute "water weight" loss, "sweat suits", saunas, hot baths, detoxes etc.
Intermittent Fasting for one is not to be confused with starvation. Where starvation is the involuntary absence of food, fasting becomes the voluntary absence of food for a certain period of time...
What happens when we starve?
During times of feeding, the average person will experience elevated levels of insulin secretion. Depending on the Carbohydrate/Sugar source, pancreatic insulin levels will either spike very rapidly or minimally[18].
Excess glucose or glycogen stores can also store as bodyfat via the process denovo-lipogenesis'[19] if no strenuous or metabolic activity takes place.
During a 24hr fasting state, insulin levels typically drop off whilst stored glycogen is used as glucose for energy. As your body stops getting adequate fuel from food, your body also signals to increase development of GH (Growth Hormone).
Whilst GH is believed to cause an anabolic response in muscle building, the increase in GH from fasting doesn't cause an overall significant increase in skeletal muscle via anabolism. Simply rather an increase in total body water (LBM) and connective tissue only[26].
Alternate day fasting (IF sub-type) where partial or complete 24hr restriction of energy intake is believed to also be superior to Energy restriction[23]. However, there are still many misconceptions surrounding fasting.
In the following 1-2 days post 24 hour restriction, many of the end products of digestion (i.e. noncarbohydrate sources) and proteins are broken down into its constituent amino acids by various metabolic processes and a process called 'gluconeogenesis'[20].
Lastly 'Ketosis' where your body switches over from a non-existant primary energy source (glucose/glycogen) to dietary fat (ketones) as an alternate fuel source[21].
What happens when we eat?
As soon as we begin the process of eating, we 'trigger' natural phases of hunger and nourishment for any given 24hr period. Typically most individuals will instinctively then need to consume meals every few hours (3-4) because of this.
Now here's the theory, if one were to delay eating by a certain period of time, you would also delay the initial 'eating trigger' for an extended period of time. Much of how this 'trigger' works is still unknown, however we do have some good clues:
The mechanisms for controlling hunger revolve around a brain structure known as the 'hypothalamus'. The hypothalamus performs a central role in many hormonal and regulatory functions in the body [1] i.e. Body fat, Weight, Hunger regulation etc.
Eating less frequently by fasting helps control 'ghrelin' production (hormone associated with hunger). Estrogen a key metabolic regulator also influences certain peptides and neurons i.e. cholecystokinin to assist in the feeling of fullness.[7]
A recently discovered hormone 'leptin' helps the brain determine how much fat to store[30]. Alongside this, the brain also makes a chemical called 'neuropeptide Y' linked to significant increase in appetite and insulin production.
These hormones have a synergistic effect in controlling overall hunger, the unopposed effect being gross obesity[2]. However many of the finer details are still a mystery.
ON COFFEE
Did you know up to three quarters of Australians drink at least one cup of coffee a day?
The love of coffee is strong here in Australia, so much so that many claim to not be able to live without it! On average up to 75% of us enjoy at least one cup of coffee per day, with a further 28% have three or more cups per day![3]
Contrary to popular belief, coffee has many health benefits in comparison to other sources i.e. berries or wine. Spawning back from the 'seeds' of a coffee plant, coffee beans are a source of antioxidants along with reducing disease risk and increased recovery agents. Hundreds and hundreds of potentially bioactive compounds abound in each delicious sip[2].
Coffee is also high in polyphenols and may have a protective role in degenerative diseases such as brain diseases like Alzheimer’s, cardiovascular disease and even certain cancers...
Perhaps one of the most impressive attributes of Coffee is its influence on energy intake, performance and perhaps even appetite suppression[4,5]. In a controlled research study to determine if coffee and/or caffeine enhanced endurance and performance, results appeared to favour caffeine capsules over caffeinated for improving overall endurance performance.
The authors speculated that one such family of compounds, collectively called chlorogenic acids, interfered with the performance-enhancing effects of caffeine[1], and there is some evidence indicating that such a mechanism is plausible[3].
Caffeine is also one of the most frequently studied performance-enhancing supplements being used and studied today. However, much like pre-workouts the alertness response to caffeine tends to decrease after habitual consumption. Part of the alertness response appears to also be individual with enzyme and iozymes i.e. CYP1A2 responsible for caffeine metabolism.
Most individuals report of some days caffeine improving performance whilst other days not. There are probably several factors that also contribute to this habitual 'flip-flopping' including the added placebo effect from caffeine[8].
Of the current evidence some suggests caffeine has weak transient effects on energy intake and appetite control. However there is also some evidence that points to the caffeine source^.
Due to genetic/individual differences and responses, some individuals are considered “fast” caffeine metabolizers, some are “slow,” with the remainder of the population somewhere in the middle...
INTERMITTENT FASTING BENEFITS?
Intermittent Fasting is often seen as the simplest answer to Weight management...
It is a change in perspective from "What should we eat" to "When should we eat"?
Thus allowing individuals to create a Calorie deficit anytime, anywhere.
But is irregular and sporadic meal frequency really the secret to Fat loss?
In a recent comparison between Energy Restriction and Intermittent Fasting in overweight individuals, all studies demonstrated comparable reductions in body weight where overall energy intake was matched[9].
A meta-analysis also concluded that ER involving IF on at least one day per week but no greater than seven days was equally effective as Energy Restriction for short-term weight management[10].
Furthermore, the majority of trials reporting body composition outcomes have shown equal efficacy for reducing Fat Mass i.e. visceral fat stores, and waist circumference with IF compared to Energy Restriction in overweight/obese adults[11,12].
Much like any other diet however, Intermittent Fasting is NOT magic.
PROS & CONS OF INTERMITTENT FASTING?
Within the current general population, the most common nutritional weight loss strategy implemented is continuous energy restriction (CER) for most of the duration of their dietary lifestyle[13,14].
A recent study however investigated the effects of calorie restriction versus intermittent fasting. What they found was whilst you generally oxidize more fat in the morning (IF) you also oxidize less fat at night.
Subsequently when you don't fast you oxidize less fat in the morning and more fat at night. In other words, during times of fasting more fat is oxidized whilst during times of feeding less fat is oxidized. Part of this stems from not having carbohydrates subsequent (glucose) in your system during day break. Your body will either use this as fuel or will primarily rely on fat. Over a 24-hour period however, you oxidize the same amount of energy (carbohydrates and fat) whether intermittently fasting or not. Additionally, the study also found consuming breakfast or fasting having no significant impact on boosting metabolic rate or greater fat oxidation over a 24hr period[31].
Research shows eating every 3-4 hours in particular protein stimulates MPS (Muscle Protein Synthesis) more so than fasting GH. Furthermore multiple studies show far greater anabolism through multiple protein feeding periods as opposed to 1-2 big meals through IF[25,27].
In lieu of this, some evidence suggests meal skipping, does not impair hypertrophy or strength gains in resistance trained women (Tinsley et al, 2019). However, subjects in a previous study did much of their resistance training in the fed state, with their workouts falling within their feeding window[32].
They also investigated the performance effects of breakfast skipping i.e fasting overnight then exercising post standard breakfast and water loading. Subjects were unsurprisingly more hungry when they skipped breakfast, but also completed significantly fewer bench press and squat reps.
Another study looked at TRF (time restricted feeding) versus non TRF between 2 groups. The group whom consumed their allotted kcals within a 4 hour feeding window following TRF found no impact on their total body composition. Whilst both groups increased in endurance, size & strength, the non TRF group experienced greater lean muscle mass gains[33].
According to further literature, a calorie equated diet results in favor of up-regulation of detoxification in both the liver and the intestines[16]. A lot of the 'detoxing' properties can be derived from caloric restriction alone as opposed to traditional detox/fad diets.
Whilst the available evidence indicates that IF is not superior to ER as a weight loss strategy, For some individuals however, IF is a viable strategy and the simplest form of calorie restriction one can adhere to.
Further to the available evidence suggesting that fasted training is unlikely to significantly improve your training performance, it does have the potential to impair performance for many lifters.
Combined with some of the variable ingredients mentioned above i.e. caloric restriction > potential health benefits, it’s still probably a good idea to make sure that training occurs in a fed state.
Pro's:
✔️ Little to No Self-monitoring required
✔️ Large amount of (short term) Weight loss i.e. glycogen/water
✔️ Little to no food/beverage quantity restriction
✔️ Alternative to traditional detoxes (replace old > new cells)
✔️ Up-regulation of detoxification in both the liver and the intestines[17]
✔️ Less Vitamin/Mineral supplementation required[15] ✔️ Ideal for Busy individuals/Poor Time Management ✔️ Less Food focused ✔️ Fat loss via Calorie deficit
Con's:
🚫 Non-sustainable (long term) for most individuals due to '8' hour feeding window
🚫 Individual appetite suppression may vary
🚫 Inferior GH anabolic response[29]
🚫 Deemed too restrictive for 'social' individuals i.e. Breakfast meetings
🚫 Sub-optimal for athletes requiring frequent adequate protein > optimizing muscle growth/recovery[28]
🚫 Side effects i.e. fatigue and/or weakness
CLIENT SPOTLIGHT
Check out these amazing results from a past client:
"My journey - I wasn't concerned about weight, it was just a number! My health was my concern and I wanted to change my body and lifestyle for good. With Chris's help I achieved that! 3 kids later, who would have thought I would fit into my clothes from when I was underweight before kids (68kg) from not eating well!
It's amazing what your body can do when you feed it the right food. 😊 You know you are back in business once the kitchen scale comes out and stays out all day! You think you roughly know how much food weighs by simply looking at it.. but then you realize how wrong you are!! Over eating is so easy!
I'm now at a healthy weight and body tone. Going from 87kg to 79.7 in 6 weeks! This is a Major transformation! Not to mention toned up and ready for my wedding! And I am not done yet! My journey is still going!" - Nikki
HOW TO INTERMITTENTLY FAST?
Ok, so you're eager to give IF a go?
For most individuals, using an 8:16 fasting ratio may be too difficult to incorporate into one's lifestyle starting out.
The subject of long term sustainability is also very important.
For this reason, we are going to break down Intermittent Fasting into phases:👇
Phase 1 - Delay eating by 1-2 hours i.e. 8-9am.
Phase 2 - Delay eating by 2-3 hours i.e. 9-10am.
Phase 3 - Delay eating by 3-4 hours i.e. 11am -12pm.
Remember, Intermittent Fasting much like any diet works so long as you are in a Caloric deficit.
Delayed eating not only allows for a greater Calorie balance but also a shorter window for food consumption whilst still being results focused.
If you have an upcoming event or holiday, have a coffee and give Intermittent Fasting a go. :)
Note: It's generally not recommended to exceed a total fasting period of 5-6 hours to maintain adequate nutrient/energy balance. If you have an underlying Eating Disorder, please consult a Nutrition Coach or Dietitian before attempting Intermittent Fasting.
References:
1. Grossman, S.P., (1975). "Role of hypothalamus in the regulation of food and water intake." Psychol. Rev. 82, 200-224. 2. Travis, J., (1996). "Obesity researchers feast on two scoops." Science News, Vol. 149. January 6,1996.
3. https://mccrindle.com.au/insights/blogarchive/australian-attitudes-towards-coffee/
4. Int J Food Sci Nutr. 2017 Dec;68(8):901-912. doi: 10.1080/09637486.2017.1320537. Epub 2017 Apr 27.Caffeine, coffee, and appetite control: a review. https://www.ncbi.nlm.nih.gov/pubmed/28446037
5. J Acad Nutr Diet. 2018 Oct;118(10):1832-1843. doi: 10.1016/j.jand.2018.05.015. Epub 2018 Jul 19. Caffeine Transiently Affects Food Intake at Breakfast. https://www.ncbi.nlm.nih.gov/pubmed/30033159
6. Jason Fung, “Fasting Physiology: Part II,” Intensive Dietary Management, April 17,2015, https://intensivedietarymanagement.com/fasting-physiology-part-ii/
7. Hormone Health Network, “What Is Estrogen?”, accessed February 12, 2017, http://www.hormone.org/diseases-and-conditions/womens-health/what-is-estrogen
8. Scand J Med Sci Sports. 2017 Nov;27(11):1240-1247. doi: 10.1111/sms.12793. Epub 2016 Nov 23.Placebo in sports nutrition: a proof-of-principle study involving caffeine supplementation.
https://www.ncbi.nlm.nih.gov/pubmed/27882605
9. Behav Sci (Basel). 2017 Jan 19;7(1). pii: E4. doi: 10.3390/bs7010004.Potential Benefits and Harms of Intermittent Energy Restriction and Intermittent Fasting Amongst Obese, Overweight and Normal Weight Subjects-A Narrative Review of Human and Animal Evidence.
https://www.ncbi.nlm.nih.gov/pubmed/28106818
10. JBI Database System Rev Implement Rep. 2018 Feb;16(2):507-547. doi: 10.11124/JBISRIR-2016-003248.Intermittent fasting interventions for treatment of overweight and obesity in adults: a systematic review and meta-analysis. https://www.ncbi.nlm.nih.gov/pubmed/29419624
11. Transl Res. 2014 Oct;164(4):302-11. doi: 10.1016/j.trsl.2014.05.013. Epub 2014 Jun 12.Intermittent fasting vs daily calorie restriction for type 2 diabetes prevention: a review of human findings.
https://www.ncbi.nlm.nih.gov/pubmed/24993615
12. Eur J Clin Nutr. 2016 Mar;70(3):292-9. doi: 10.1038/ejcn.2015.195. Epub 2015 Nov 25.Intermittent energy restriction and weight loss: a systematic review. https://www.ncbi.nlm.nih.gov/pubmed/26603882
13. Int J Sport Nutr Exerc Metab. 2012 Apr;22(2):89-97. Epub 2012 Feb 15.Methods of body mass reduction by combat sport athletes.
https://www.ncbi.nlm.nih.gov/pubmed/22349031
14. J Int Soc Sports Nutr. 2012; 9: 52. Published online 2012 Dec 13. doi: 10.1186/1550-2783-9-52PMCID: PMC3607973PMID: 23237303 Weight loss in combat sports: physiological, psychological and performance effects https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3607973/
15. Med Sci Sports Exerc. 2016 Mar;48(3):543-68. doi: 10.1249/MSS.0000000000000852. American College of Sports Medicine Joint Position Statement. Nutrition and Athletic Performance: https://www.ncbi.nlm.nih.gov/pubmed/26891166
16. Cell Metab. 2015 Jul 7;22(1):86-99. doi: 10.1016/j.cmet.2015.05.012. Epub 2015 Jun 18. A Periodic Diet that Mimics Fasting Promotes Multi-System Regeneration, Enhanced Cognitive Performance, and Healthspan. https://www.ncbi.nlm.nih.gov/pubmed/26094889
17. Drug Metab Dispos. 2016 Mar; 44(3): 366–369. Published online 2016 Mar. doi: 10.1124/dmd.115.064766PMCID: PMC4767382PMID: 26744253 Calorie Restriction Increases P-Glycoprotein and Decreases Intestinal Absorption of Digoxin in Mice
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4767382/
18. How do Carbohydrates and Sugar work? On Refeeds:
https://www.thelabpersonaltraining.com/single-post/2018/01/14/Refeeds
19. NSCA – Essentials of Strength Training and Conditioning 3rd Edition. Glycogen, Bioenergetics of Exercise and Training, p33 & p190.
20. Essentials of Strength Training and Conditioning 3rd Edition. Glycogen, Bioenergetics of Exercise and Training, p33 & p190. Carbohydrate requirements p211. Gluconeogenesis p209.
21. What is Keto? On Keto: https://www.thelabpersonaltraining.com/single-post/2018/09/17/Keto
22. Pettersson, S.; Ekström, M.P.; Berg, C.M. Practices of weight regulation among elite athletes in combat sports: A matter of mental advantage? J. Athl. Train. 2013, 48, 99–108. https://natajournals.org/doi/10.4085/1062-6050-48.1.04
23. Harvie, M.; Howell, A. Potential Benefits and Harms of Intermittent Energy Restriction and IntermittentFasting Amongst Obese, Overweight and Normal Weight Subjects-A Narrative Review of Human andAnimal Evidence. Behav. Sci. 2017, 7, 4. https://www.mdpi.com/2076-328X/7/1/4
24. Australian Health Survey: Nutrition First Results - Food and Nutrients, 2011-12
25. Nutr Rev. 2015 Feb;73(2):69-82. doi: 10.1093/nutrit/nuu017. Effects of meal frequency on weight loss and body composition: a meta-analysis.
https://www.ncbi.nlm.nih.gov/pubmed/26024494
26. Norton, Layne et al., 2017; Meal Distribution of Dietary Protein and Leucine Influences Long-Term Muscle Mass and Body Composition in Adult Rats1–3
27. J Physiol. 2013 May 1;591(9):2319-31. doi: 10.1113/jphysiol.2012.244897. Timing and distribution of protein ingestion during prolonged recovery from resistance exercise alters myofibrillar protein synthesis.
https://www.ncbi.nlm.nih.gov/pubmed/23459753
28. Nutr Metab (Lond). 2012 Oct 16;9(1):91. doi: 10.1186/1743-7075-9-91. Daytime pattern of post-exercise protein intake affects whole-body protein turnover in resistance-trained males. https://www.ncbi.nlm.nih.gov/pubmed/23067428
29. J Int Soc Sports Nutr. 2018 Feb 27;15:10. doi: 10.1186/s12970-018-0215-1. eCollection 2018. How much protein can the body use in a single meal for muscle-building? Implications for daily protein distribution. Implications for daily protein distribution. Journal of the International Society of Sports Nutrition, 15, 10.-
https://www.ncbi.nlm.nih.gov/pubmed/29497353
30. Klok, M. D., Jakobsdottir, S., & Drent, M. L. (2007). The role of leptin and ghrelin in the regulation of food intake and body weight in humans:a review. Obesity reviews, 8(1), 21-34. https://www.ncbi.nlm.nih.gov/pubmed/17212793
31. Am J Clin Nutr. 2019 May 16. pii: nqy346. doi: 10.1093/ajcn/nqy346. [Epub ahead of print] Effect of skipping breakfast for 6 days on energy metabolism and diurnal rhythm of blood glucose in young healthy Japanese males.
https://www.ncbi.nlm.nih.gov/pubmed/31095288
32. Am J Clin Nutr. 2019 Sep 1;110(3):628-640. doi: 10.1093/ajcn/nqz126.Time-restricted feeding plus resistance training in active females: a randomized trial. https://www.ncbi.nlm.nih.gov/pubmed/31268131
33. Time-restricted feeding in young men performing resistance training: A randomized controlled trial. https://www.ncbi.nlm.nih.gov/pubmed/27550719
