4 02 2013
Meal spread, meal frequency and Intermittent fasting for efficient fat loss
Initially I had intended for this article to be an introductory one into the benefits of intermittent fasting for fat loss. But I recently partook in a web-board discussion, something I admittedly hadn’t done in quite a while, and noticed that apparently that there are more people that need to understand why Intermittent fasting (IF from now on, for ease of use) isn’t a valid choice when attempting to gain muscle mass as there are people who need to be introduced to its benefits for fat loss, that there are many who use IF without really understanding the benefits and downsides, and that the topic of meal frequency has become a very contested debate throughout the industry. So I decided to make this an article about meal frequency and timing in general, and go more in-depth on all the topics. It seems there is quite some polarization going on between people who think it’s a must to eat 10 meals a day, and people who think IF is a lifestyle choice for the serious athlete. As usual, both sides are wrong and the truth lies somewhere in the middle. Now, for those waiting for the IF-piece, don’t worry, I’m still discussing that whole topic at the end, but I feel I need to do some deconstructing of the “proof” out there in this discussion (I use parentheses because I think half the people citing these studies failed to actually read the entire studies).
What is intermittent fasting and why has it become such a cult ?
This is a superficial introductory paragraph to sketch some background for people who aren’t familiar with IF and its history. It contains very little useful data to the discussion at hand, so if you already know this, feel free to skip this paragraph. Intermittent fasting is the concept of extending your fast for longer periods of time and restricting the time you eat. In the not too distant past, fasting was largely restricted to religious purposes, like Ramadan-fasting (and equivalents in other religions, but they are not so widely practiced). But in recent years, under the impulse of Dr. Krista Varady of the University of Illinois, Chicago, a lot of research has been done concerning alternate day fasting as a means to impose caloric restrictions to help improve health and well-being in conditions of obesity, type II diabetes and other metabolic disorders. The major benefit, according to Dr. Varady herself, is that when you restrict your calories extremely on one day (~500 kcal) and eat ad libitum the next, that it’s hard for people to fully compensate for the calories on the feed day, and that because one always has the feed day to look forward to, that it’s easier to maintain than regular caloric restriction where one moderately restricts his calories each and every day. IF first seeped into our athletic culture under the impulse of Swedish national Martin Berkhan, who popularized what he called the Leangains method, which consists of a larger daily fasting window, restricting caloric intake to a span of 6-8 hours each day. When I initially heard about IF, I largely dismissed it, because it seemed like the latest diet fad, like we have had at least one every year, where people try to make things way too complicated, blaming our Western metabolic problems on nearly everything (despite the fact that most factors were already present prior to the obesity epidemic). These diets are usually based on limited information and fade back out of the picture after a few months, if they are lucky, years, as the epidemic of obesity continues to spread unabated. These diets usually take on a cultist form with people following it, based on flawed or poorly interpreted research, parroting it along, and attacking anyone who threatens their new view of life. IF is no different, and I predict a similar future for it. That’s a shame, because there is some merit to it in limited context, for more efficient fat loss. If I hadn’t heard about it in recent months from a much more reliable source, I would have probably never bothered to look into it, but it does offer distinct benefits for efficient caloric restriction. Sadly, the cultist status and dogmatic nature of IF has many believing it is a valid lifestyle choice for an athlete in general, rather than a tool for fat loss and caloric restriction, even when they are trying to gain muscle mass. To find the origin of this cultist status, one needn’t look further than Berkhan himself. When I first visited his website it painted the picture of an eloquent man, with decent but limited scientific background, who was very passionate about what he did, and even though he made several mistakes, I attributed them mainly to overzealous interpretation of the data in light of his own view and nothing more. Since reading more, and having spoken to some IF-acolytes, and especially after his latest blog, I alas had to review my original assessment : He is an extremely self-absorbed egotist who purposely ignores and masks information in contradiction with his world view, chasing absolute dogmatic obedience of what he deems correct, and belligerently attacking anything that threatens that view. He seems under the impression that he owns the concept of IF, and that anyone who speaks on the subject is infringing on his rights, and that no one else but him can possibly be right. Now I partially understand where some of the sentiment comes from : he is very passionate and when popular media truncate and simplify what you do it can be frustrating. But that’s what popular media do, and it doesn’t detract from what you do and say. Or like I always say : you can’t teach those who don’t want to be taught, but as long as they don’t mention my name, they can say whatever they want. If you are serious about something, your business is to educate, not to impose. It means you do your thing in spite of all the rest, and it does not mean you act like a depressed victim because someone else happens to be talking about the same subject. Besides that, his own scientific standards, as I intend to demonstrate, are not exceptionally high, so he probably shouldn’t be trying to speak from the moral high ground, for fear of falling. To that end I feel we need to deconstruct a lot of the information put out there.
The discussion of meal frequency
The popular stance in the industry has been that a larger number of meals per day are better, and a lot of what IF’ers are trying to prove is that this is not the case. And you know what ? They are right. A lot of very valid data has repeatedly proven that a lower meal frequency is better for weight loss and management, and shown meal frequency per se to be irrelevant to muscle gain. Increased meal frequency remains a valid tool for muscle gain however, simply because it makes it easier to increase the number of calories ingested over the course of a day, which is a major problem for a lot of people. It certainly makes increased meal frequency a must for professional bodybuilders, because it’s simply not possible to consume the amount of calories they do in 4 meals (Ronnie Coleman used to eat 6000+ calories from carbs and protein alone at certain times). Does that mean the average recreational lifter should eat 10 meals a day ? No. Because as we will also demonstrate, a peak in amino acids is crucial to gains, so that spreading a limited amount of calories too thin has an opposite effect. 4-5 meals per day is probably a good guideline for most people, with more meals only coming into the picture when it becomes hard to get all your calories in that amount of meals. The thing is that IF’ers have been using a lot of this data on meal frequency to validate their lifestyle choice, but they conveniently ignore the fact that all the studies done in this regard compare a number of meals in a SPREAD pattern. Like 3 spread meals versus 6 spread meals. Not a single one of these studies is conducted with all the calories centered in a very limited time frame of hours, in fact, when looking at the data with 1 or 2 meals daily, the satiety factor that is so big with the defense of reduced frequency goes out the window.
A critique of Alan Aragon’s article and the studies he cites
A lot of the fuel for the debate around IF has come from an article by Alan Aragon entitled “A Critique of the ISSN Position Stand on Meal Frequency”, reprinted by Berkhan on his site. Now I don’t want to critique Mr. Aragon himself, because despite many of his mistaken interpretations in said article, I do agree with his general stance he assumes in the article. I’ve also not read anything else by the man (apparently he charges money for the privilege ?) and from nothing I’ve read can I deduce he is necessarily a vanguard of IF, the way Berkhan would have you believe. So I want to leave that part out of the discussion, and limit myself to this one piece of his, because much of the research cited by IF’ers seems to be copy/pasted directly from it.
Now, let me make my own stance very clear here in a separate paragraph : I personally believe that IF can be a tool to more efficiently lose fat, something I will discuss at length later on. I also believe most of the health benefits associated with IF are a direct result of the caloric restriction involved, but I am adamant that it WILL impede optimal gains on a hyper-caloric diet for an athlete attempting to gain muscle mass. This last part is what I wish to address.
To that end I’m not going to go over every single study with regards to IF on caloric restriction. Yes, increased fasting will lead to muscle protein loss, but no that doesn’t mean you end up with less muscle mass at the end of the ride (in terms of myofibrillar protein, the kind that matters, it may even have a more sparing effect). Again, that will be discussed in that context later. Rather I want to focus on the fact that the health improvements are related solely to caloric restriction (i.e. that a hyper-caloric IF offers no additional health benefits) and that this lifestyle will impede muscle gain. As Aragon himself recommends with the ISSN mission statement, I’m going to recommend that you read his article alongside mine to draw your own conclusions. First, let’s have a look at his section “Missing Research on Glucose Control”. He cites the Carlson study (1) that factually demonstrated that insulin resistance was worse on 1 meal a day instead of 3. He cites the authors in stating that there was a much larger consumption of food in closer proximity to the test in the 1 meal a day group, since they consumed their meal hours before bed and the test was in the morning, however that argument doesn’t really work, since such tests are usually conducted in the morning because, medically, that is the definition of a fasted state. He then cites Holmstrup et al. (2) who found that during caloric restriction (!) glucose levels were higher in a 6 meal a day group compared to a 3 meal a day group, but for the IF’ers using this as an argument, not only was this on caloric restriction, both groups were on a spread pattern, not an IF pattern. Lastly he cites Harvie et al. (3) who found no difference in effect for decreasing bodyweight and increasing insulin sensitivity on intermittent or continuous energy restriction. This last study, for me, really tells the whole story : the health benefits observed with most IF studies are the direct result of the caloric restriction, and not the IF pattern. Although not conclusive, the Carlson study at least points out that in a hypercaloric diet, there is a risk of reduced insulin sensitivity. And just to be clear : insulin resistance + hypercaloric diet = obesity. Simplified, but true.
Even more interesting than this however are the studies he cites in his section titled “Missing Research on Markers of Protein Metabolism”. First up is the much-quoted Soeters study (4), which uses a hyper-caloric diet and an alternate day style 20h fasting pattern, a correct reflection of what IF would look like on a hyper-caloric diet. In this study Soeters et al. found no difference in glucose, lipid or protein metabolism between the IF group and the control group. First thing that stands out is that both groups had about 8 people and the study lasted two weeks. This study basically screams Type II error (not finding a difference when actually there is one), but ignoring that fact, even then the study clearly demonstrates a lower phosphorylation state of mTOR in the IF group, something that over an extended period of time will surely result in a decrease in muscle mass accrual since mTOR is the key signal integrator for muscle protein synthesis (read here for more information). They also found a greater phosphorylation of the upstream Akt protein kinase, which is likely the direct result of reduced negative feedback by mTOR on the insulin receptor substrates (5), and indicative of states of lower muscle mass accrual. This also indicates a direct inhibitory effect on mTOR. This is probably also the effect that causes the life extension benefits frequently discussed in regards to IF. Lowering mTOR has been shown to have positive effects on attenuating cancers, increasing cancer survival and increasing lifespan due to lower ROS production. Sadly if this is your goal, you as an athlete, have probably chosen the wrong lifestyle, since ours is all about maximal mTOR activation. Next up are the Arnal studies (6,7). I don’t think Mr. Aragon even bothered to read these studies, since in his article he seems to clearly be under the impression that in this study the test group consumed most of its calories in one meal compared to the control group. This is most certainly not the case since the distribution of calories for the test group and control group respectively were 17-51-32 across three meals and 21-49-15 across 4 meals ( the 49 was two meals of 34 and 15%). Both groups had a spread meal pattern comparatively close to the distribution of a standard diet, and comparatively close to each other. The only difference was that the test group consumed 80% of its protein in the middle meal, where the control group spread its intake across the 4 meals evenly. Even in this context, which has absolutely nothing to do with IF, since the test group still consumed 3 spread, reasonably high calorie meals with some protein, there was probably a difference because of a variable that was not accounted for. The previous study (6) was in older women and found that a pulse pattern of protein feeding was better than a spread pattern of protein feeding. This is consistent with studies in older men clearly demonstrating a type of anabolic resistance with age (8), requiring a higher threshold of blood amino acids to stimulate protein synthesis. Other research (9,10) shows this is not the case for younger men, where a spread pattern is better for nitrogen retention and muscle protein synthesis, and that would apply double for people like us, who consume so much protein, that even if you spread it across 5 or 6 meals (or for pro bodybuilders more) you will reach the threshold required for muscle protein synthesis. The newer study that Aragon cites, in younger women, concluded there was no significant difference in nitrogen balance between spread or pulse protein feeding, however, and permit me to quote the authors of the study themselves
“Another issue that arises in comparing the effect of the protein feeding pattern in young women concerns the fact that in this study, the menstrual cycle was not taken into account (which obviously wasn’t a problem with the older women). However, it appears that protein turnover and leucine oxidation increase during the luteal phase (Lariviere et al. 1994). The failure to account for this cycle could lead to an increase in the intersubject variability (Calloway and Kurtzer 1982). We cannot exclude that such a variability prevented us from detecting the diet effect on nitrogen balance”
Indeed, the pulse group had an unusually large variability that masked the difference that there was a more positive protein balance in the spread group, than in the pulse group in the younger women, consistent with reports in younger men (9,10) that a spread pattern of protein is better in this age group. Besides, as the majority of people at hand citing this stuff were, in fact, men, the fact that there is one study that found no difference in a pulse and spread protein pattern in women would be fairly moot, even if valid, which is not the case. Perhaps to expand a little bit, the theory of a higher anabolic threshold in older people suggests that more of an elevation in blood amino acids is required to achieve the initiation of an anabolic effect, so that when eating the same amount of protein, it is best to concentrate it in fewer meals so that those meals will cross the threshold and you will have some, rather than no anabolism. It also implies that if you simply increase the amount of protein ingested so that EACH meal crosses the threshold, you will create anabolism with EVERY meal. This is relevant because we are in a population group that consumes a whole lot more protein than most and barring the few senior citizens among us, we have a lower threshold, meaning we can easily cross our threshold for anabolism spreading that protein out over a considerable amount of meals.
In his section “Missing research on body composition” he also cites a study by Dr. Varady herself, a literature review (12) that supposedly concludes that intermittent calorie RESTRICTION is equally effective for weight loss, but may be more effective for retaining lean mass. I haven’t examined all the studies in the review individually for their relevance, but find the conclusion premature. In all likelihood, it will be about similar in the situations most athletes place themselves in, although there are minor biochemical benefits in regards to muscle retention (again, discussed later on). It is however completely beside the point, even if the conclusion is accurate, that IF’ers use this review to claim that this will lead to more muscle mass gain when on a hypercaloric diet. Aside from the clear indications that this is not the case from previously cited studies, I’d also like to quote Dr. Varady herself in an interview from 2010 when asked about the combination of IF with resistance training : “I THINK IT WOULD BE DIFFICULT FOR THEM TO BUILD MUSCLE MASS”.
Lastly he goes into many of the studies about satiety, which as mentioned previously concern a spread pattern of meals, and not an IF-style type of feeding (11). None of these apply to starving yourself for 16 hours straight.
The burden of proof
This follows directly on the previous paragraph, but I wanted to separate the two. Like I said, I don’t want to put Mr. Aragon on the spot since his aim with the article was to challenge the need for high meal frequency, and I agree with that stance. Nothing in the limited sample of his writing that I have seen indicates he is an IF-aficionado, so I don’t want to brand him such, and therefore wanted to make a clear separation between my critique of his article as cited by IF’ers, and my concluding remarks on those IF’ers. Those concluding remarks concern the burden of proof. Thus far, there is very, very little, if any research left that even HINTS that IF is suitable for muscle gain, let alone the most effective way to do it. There is actually relatively little evidence, short of what I’m about to write later on, that it’s a superior way to lose fat. At best, and Martin Berkhan’s site proves it more than anything, IF’ers manage to do a relatively decent job to demonstrate that on a hypo-caloric diet, an IF-style pattern is no less effective than a spread pattern, with similar results and markers of health. So pray tell me, why on God’s green earth would I starve myself for 16 hours or more when I don’t have to ? I mean that seems like a fairly pointless thing to do. Why starve yourself at all if your goal is to gain mass ? And this seems to be the main problem I have with most IF-cultists : Not a single one of them has been able to give me a more satisfactory answer to the question of why, if it’s not more effective, would I change what I’m doing, other than “because I feel like it”. Now if that’s the case, be my guest. As I keep repeating, it’s not my goal to impose my beliefs on you and say you can’t do this. I’m just providing the information you need to know. If you absolutely, positively feel you like to starve yourself 16 hours and eat for 8 because you want to or it makes you feel better, or special, even if it’s likely to impede muscle gain, then by all means go ahead (it also doesn’t mean you can’t gain any muscle, depending on current level of training, using an IF pattern, just that you are making it harder to do so). But please, please, don’t attempt to impose your delusional world views on others. If you want to share your thoughts and promote a possible way of life as superior to the one most people lead, then please accept that the burden of proof is on you to demonstrate the clear benefit of such a lifestyle (and that burden of proof does not equal copy/pasting misinterpreted studies you have not read – that’s the definition of dogmatic). Because so far, what I’ve seen is of bitter little substance.
The importance of meal frequency in muscle gain and fat loss
It is rumored that the esteemed Stuart Phillips is coming out with new research demonstrating that 4-5 meals per day is the ideal meal frequency. That is certainly research I’m looking forward to. From what I gather he is going to attempt to demonstrate that both more meals and less are less favorable. The idea however that more meals are less desirable is usually based on a single study (13) showing that muscle protein synthesis tapers off with a continuous infusion of proteins during parenteral nutrition. They use this as a means to claim that more meals would lead to lower protein synthesis. However, if you know how this process works, you understand that a continuous infusion would lead to a stable level of amino acids in the intra- and extra-cellular space that would shut down the amino acid shuttles needed to transport amino acids into the cell, elevate intra-cellular levels and initiate or maintain protein synthesis. No matter how you eat, digestion is never going to lead to such a pattern of amino acid supply, it’s always going to lead to an oscillating pattern with highs and lows. So there is nothing wrong with more meals. It then becomes a question of “is it necessary to consume more meals”, and as you may have gathered from my agreement with Mr.Aragon’s stance in his article, the answer is, in most cases, no. I’m of the same opinion as (supposedly) Dr.Phillips, that 4-5 meals is more than sufficient for most people to supply the needed calories and protein. However, just as research proves a reduced meal frequency is better for satiety, it implies a higher frequency is better to reduce it. And in all my years training people, if there has been one huge bottleneck with a lot of people, it has been getting them to consume enough calories and protein to get them to accrue the muscle mass they desire. And believe me, for those people, one or two extra meals make all the difference. I personally was a hard-gainer until my Football coach taught me to set my alarm to go off every hour and eat something small, anything. I guarantee you within a week I was ravenous with hunger all the time, and after just 10 months I had gained more mass than in the previous or following years combined.
Maximum protein dose and spread
The other side of the coin is the discussion about the “limited amount of protein per session” argument. Research with whey protein has shown that a dose of ~25g of whey (akin to ~10g of essential amino acids) is optimal, with more not providing an additional benefit on muscle protein synthesis. Although we can’t pin ourselves on that number because of relation to age and weight, and the fact that in these studies they use pure whey protein or essential amino acids, which take next to no time to digest and peak blood amino acid levels. Most protein dense foods in mixed meals take quite a bit more time to digest and spread their protein delivery out across time. Some proteins, like micellar casein seem to extend it to upwards of 7 hours. Nonetheless research has since confirmed that there is an upper limit to the amount of protein we can use for muscle protein synthesis at any given time, and Bilsborough et al. (14) have determined that level to be 6-7g of protein per hour. The per hour statement is crucial here, since it implies that that dose needs to be achieved hourly to get the most protein synthesis on a per-day basis. Again, the 6-7g is not an absolute in my personal opinion. First of all in regards to protein synthesis I think that dose is based on average bodyweights, so that we can safely state that for more muscular people 7-8g is probably more accurate. After that we can’t dismiss the use of extra protein in other capacities. For instance in lower carbohydrate diets an amount of protein, specifically from glutamine and alanine (both abundant in high quality protein like whey and casein) will be needed to fuel gluconeogenesis, so protein doesn’t have to be harvested from muscle (in hypo-caloric diets the majority of endogenous glucose production is from gluconeogenesis regardless). Likewise muscle doesn’t stop accumulating amino acids once it reaches its maximum for incorporation in protein synthesis. Wolfe and Deutz (15) postulated there was no limit to protein intake because of these other effects. They specifically discussed inhibition of protein breakdown, but I don’t think that’s a major issue, since we know 30mU/L of insulin will inhibit muscle breakdown by 50% and more will not have an effect, and that protein rich in leucine and/or arginine will already stimulate insulin well beyond that point (16). It’s unlikely more protein will have more of an effect here. But the further accumulation of glutamine especially has functional relevance to A) feed the glutamate-AKG incorporation into the krebs cycle, B) fuel the leucine pump to initiate amino acid uptake and muscle protein synthesis for future meals and C) provide a readily disposable source for gluconeogenesis when muscle is harvested. This last one may be one of the reasons in some of the studies in Varady’s review (12) muscle retention ended up being better with IF on a hypocaloric diet : the higher accumulation of amino acids beyond protein synthesis by the larger meals, would provide a larger disposable pool of glutamine to fuel the body in energy stress, saving myofibrillar protein from catabolism. So while muscle catabolism can certainly be staved off the same or better with an intermittent pattern, the maximum use of protein for protein synthesis on a per hour basis indicates that a spread pattern is simply required for maximum muscle accumulation. Combine that with the Soeters data (4) that mTOR is significantly lower on IF patterns and it becomes painstakingly obvious that if you do not observe a spread meal pattern, you are shooting yourself in the foot with regards to muscle accrual. That spread pattern should cover the half-life of the peak of the digested protein, so that you would, for most mixed meals, again arrive at something like 3.5-5 hours between meals (provided more meals are not required for calorie intake). Now assuming we sleep 8 hours, spread our meals out every 4-5 hours and end with a large casein shake before bed, we can cover pretty much 22 hours of the day. If you assume the 7g/h mark for protein synthesis for an average 80 kg man you come out to 1.9 g/kg protein consumption daily. If you factor in the “better safe than sorry” approach and the use for additional protein beyond protein synthesis, you’ll find you are pretty damn close to the standard bodybuilding recommendation of 2.2 g/kg.day. That, in my book, makes it safe to offer the recommendation of saying one should consume adequate calories with at least 2g/kg protein daily, spread out across 5 evenly spread meals (more if you have trouble meeting calories and/or protein), with the last meal being a casein-rich one for the purpose of maximal muscle gain. This by the way conforms to a 3 meals a day pattern with a pre-or post-workout meal or shake and a shake or meal before bed, which isn’t a huge lifestyle change for anyone.
Intermittent fasting for fat loss
So now that I’ve literally used nearly 7 pages to explain why IF is ill suited for muscle gain, I think it’s safe to go back to the initial goal of the article, namely explain why IF is actually a valuable tool for fat loss. I honestly admit all of the stuff above kept me from even looking at IF closely, and if not for a reliable source, I may still not have looked at it, at all. But once you do look at it, you begin to see some distinct benefits for a fat loss diet. First off, I should probably take a page from the IF manifesto and contradict the notion of “multiple smaller meals per day” being required for maximal fat loss. Actually I think the above and my previous article on the High Protein diet do a pretty good job of explaining it, but let me summarize it briefly. As we aptly stated throughout this article and as was proven in (), 3 meals per day induce greater satiety than 6 meals. That’s logical if you consider my whole argument that the only way you need more meals than the recommended 5 per day, is if you have trouble getting in adequate calories. On a hypo-caloric diet, less meals means more satiety from a single meal, and extended satiety until the next meal. One of the main benefits of IF according to Dr. Varady, as stated earlier, is that people can maintain it better because while they have to dig deeper to stay the course in their fast, they have a moment of gluttony to look forward to that makes it more bearable. If you eat 6 small meals per day, all you have to look forward to is your next small, unsatisfying meal. To date, this is one of the few very tangible and established benefits of IF diets I have seen.
The recommendation to eat more meals per day, for decennia, has been taught to us with the idea that more meals enhance metabolism to a greater degree. However energy expenditure is divided in three main groups : Resting energy expenditure (REE, also called BMR or basal metabolic rate), Energy expenditure from activity and Dietary Energy Expenditure (DEE, previously called TEF, the thermic effect of food). That last part means that an amount of calories are expended to digest and process a meal, and that was the supposed rationale behind more meals = more calories used. However DEE is typically expressed in a percentage of the calories ingested, and indeed the research (16) is fairly conclusive that DEE is in direct relation to the amount of calories ingested, meaning no matter how you spread them out, isocaloric diets with the same macronutrient ratio will yield the same DEE. As discussed in the article on the High Protein Diet, the only way to manipulate your DEE is by changing macronutrient ratio, where protein yields a DEE of 20-30%, carbohydrates 8-10% and fats 0-3%, again establishing the need for a high protein diet (20).
The final conclusion is that there is obviously no need for multiple small meals a day when dieting, on the contrary, and I fully follow Dr.Varady’s statements that the IF pattern she uses is more suited to diet compliance for most, because of the mental aspect of a high calorie day after the extreme fast, and the fact that it’s hard to make up for the calories from the fast during the feast (another good reason why it’s ill suited for muscle gain, you just can’t make up for the calories you don’t eat).
The fatty acid oxidation principle of recomposition
If you are like most people you follow the principle of “if it ain’t broke, don’t fix it”, which probably has most people successful in this sport wondering why on earth they would change a winning formula to take up IF. Well, because I firmly believe that it can shave time off your total diet, alongside making things easier. The reasoning is easy. When your body goes into acute energy stress, anabolic processes shut down and muscle and liver switch to systemic resources, meaning they switch to the bodies fat reserves to provide their energy. This initiates processes of lipolysis (the release of fat from fat cells) and fatty acid β-oxidation (the burning of fat for energy). However whenever you eat a meal, you will create an insulin and incretin response, and these hormones signal the body that there is new energy incoming, and initiates a number of anabolic processes to store the energy, in the process shutting down lipolysis and fatty acid oxidation. No more fat for fuel. That means the more meals you consume over a spread pattern, the more often you inhibit these processes, who need to be restarted each time after all the food has been processed. Now I have no time frame for these things, so I’m using a hypothetical number of 2 hours of inhibition for a meal (could be more, could be less, just using it to explain the math). If you eat 6 meals, well spread out, you will be inhibiting the use of fat for fuel for 6×2 hours = 12 hours. If you are eating 3 meals inside a 6 hour window, your maximum inhibition is 6h+2h = 8 hours. That means following an IF pattern you will spend 4 more hours burning fat as fuel than you would with a spread pattern. The fact that you do that also implies 4 hours of reduced protein catabolism. Now there is a need for amino acids, since on a hypo-caloric diet the majority of endogenous glucose production comes from gluconeogenesis rather than glycolysis, and in the fast your muscle will give up some protein, longer than in a spread pattern. But because fat is being used as the principle fuel source a lower amount per timeframe is being released because there is less need for endogenous glucose production. Combine that with what know of muscle storing increased amino acids beyond what they incorporate when you eat meals denser in protein than required (as you would, compressing the same amount of protein in just 6-8 hours), which would have a sparing effect on myofibrillar protein, and it’s easy to understand how an IF pattern will cause you to lose procentually more fat than muscle, shaving time off your diet to reach your goal and having a mild muscle sparing effect.
And despite all that, 99% of IF’ers don’t even know this.
How to do it right
All of the above only increases the efficiency of a diet. We are talking small percentages here. It doesn’t change the basic principles of dieting. Now every little bit helps, but you probably understand that you can’t afford mistakes that negate the benefits, and that seems to be a concept a lot of IF’ers do not understand. For instance, your resistance training should fall squarely inside your feeding window, NO EXCEPTIONS. Your resistance training creates an optimal anabolic window (17) (see corresponding blog), and centering most of your protein in this window is likely to increase your (muscle and splanchnic) protein accumulation in that period. Not only do you not want to waste this, some of the practices I have seen IF’ers recommend to suggest you can in fact work out in your fasting window are plainly ignorant. For instance I have seen the suggestion that you can train in your fasting window if you consume 10g of BCAA’s each before, during and after your training. As discussed extensively in the article on pre-and postworkout nutrition, free form BCAA’s do nothing to stimulate protein synthesis by themselves, but more importantly, leucine is an extremely potent insulin trigger (16) that would negate the benefit of extended fatty acid oxidation and must be avoided at all costs during the fast.
As much as it pains me to say, the leangains type IF, with a fast and a feed every day, is best suited to athletic purposes, because it becomes exceptionally difficult with alternate day fasting to keep track of allotted calories, which is an issue if you are getting ready for a contest or shoot and are on a strict time table.
Literally almost any type of food will in fact create an insulin or incretin response, so the repeated question “can I have X or Y during my fast” that seems to be popular on literally every discussion on IF on web-boards is a moot one. If you must eat something to maintain your fast, you may like the semi-intermittent fast below. Now if you have trouble maintaining your fast, then it should CERTAINLY be obvious that with potentially worse results and no added benefit, you should DEFINITELY not be using an IF-lifestyle while attempting to gain muscle.
The semi- intermittent fast
Of course not everyone feels like starving themselves. One may decide he wants the famine/feast principle, but with smaller meals during part of the day and a larger meal at another time. For many people that would increase diet compliance even more. It’s certainly an option, since diet compliance seems to be the main benefit of any IF pattern. It then becomes key to use foods that impede fatty acid oxidation less than others. For instance we already know that the resistant starch HDP not only maintains fatty acid oxidation better, while reducing calories absorbed, better than other carbohydrate sources, it also lowers the insulin and incretin response to other foods co-ingested with it. Research also shows that a slow digesting protein like casein (18) has a lesser impact on AMPK phosphorylation (the driving force behind fatty acid oxidation) than most foods, likely because at normal doses (20g) it doesn’t cause a significant spike in insulinogenic amino acids due to its slower release pattern (and because proteins do not have an incretin response (19)), consistent with previous research that protein improves glycemic control (21) due to a slower release rate, despite the potent insulinogenic effects of amino acids (16). That makes a combination of casein and HDP very suitable to fill you up, provide additional protein to halt muscle loss even further, without notably affecting fatty acid oxidation (although of course it will slightly). Things like a simple pudding if you have pregelatinized HDP, or pancakes if you have ungelatinized HDP, can be tasty ways to support your diet compliance even better, but maintaining the basic principle behind IF.
Bonus fact : save on fat-burners
The principle effect of any type of fat-burner is to suppress appetite. The IF style pattern means you really only need to take one dose (or half a dose in my case) in the morning and survive until 15.00 before you can eat again, where keeping with a spread pattern of smaller meals probably requires the use of appetite suppressants throughout the day at the end of your diet.
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