A few myths addressed, and basic macronutrient requirements
In the previous installment, we gave a basic overview of the process of digestion and nutrient absorption. Before moving on to the real application section (designing your diet for maximum energy), it’s important to discuss a few implications of what’s been written already, and perhaps dispel a few myths in the process. First, the protein myth, and the story on gluten and paleo diets. If you wish to get straight to the application portion, feel free to skip the first two sections!
How much protein can I process at once?
The old myth that the body can only digest so much protein in one sitting can trace its roots back to old studies that showed a negligible increase in net body mass gain in standardized patients when given more than x number of grams of protein per day (which was then broken down to x number of grams per meal). Many individuals (read: the internet) then went on to make a connection from this to data on the mean rate of amino acid absorption in the small intestine (5-10 grams per hour, depending on study), and decided that 30 grams of protein per sitting was the body’s upper limit. Of course, this ignores many, many factors.
1) The 5-10 gram per hour rate is not absolute, this is a mean rate that can be altered based on GI contents, meal size, body size (larger individuals have more square inches of surface area in their intestines), etc. In fact, given that 95-99% of all ingested protein is absorbed (depending on protein source), this “standard” rate becomes, essentially, meaningless.
2) The studies showing negligible gain in body mass were conducted on the average population, and the endpoints were NOT performance based in any way. In other words, these were not athletes, and endpoints such as time for return to peak performance following training, lean muscle mass gain over time (for athletes), or minimal lean muscle mass lost while dieting were not taken into account.
3) Given the relative times of digestion of various meals, the 30 grams per serving figure is even more meaningless. 30 grams of whey may be through your stomach in 2 hours, while 30 grams from a ribeye steak may take 5 hours to fully process and make it to your small intestine. Certainly this changes the definition of “per sitting”.
So the bottom line- there is no real upper limit to the amount of protein your body can absorb per sitting. Certainly, many athletes take in more protein than they need (more on this later), and chances are even large individuals engaged in intense exercise rarely need more than 2g/kg a day, though there is no harm in taking in more. (The author, at 102kg, noticed no loss in skeletal muscle despite 20-30 hours of cycling and running per week in addition to heavy lifting, while taking in approximately 200 grams of protein per day). Also important is noting that this does NOT need to be spread out across the day to be effective. In fact, though amino acids are not “stored” like fats are (in adipose tissue) or carbohydrates (as glycogen), many of the amino side chains are being constantly converted and shifted from one molecule to another, and can remain in the body for quite some time in one form or another until eventually being either incorporated into existing structures or excreted/used for energy.
Should I avoid gluten and grains? Also, Paleo?
Many athletes do traditionally focus heavily on certain gluten-containing carbohydrate sources, including pasta, bread, granola bars (which can contain trace amounts, even in non-wheat based bars), etc. There has been a movement lately to limit gluten intake, in part because of misunderstandings regarding the protein itself. Should gluten be avoided? If you have celiac disease, absolutely. If you do not, then there is no real reason to. Here is a short list of known negative side effects of wheat gluten in healthy individuals.
1) That more or less covers it. Gluten itself is a much-misunderstood protein source. Found in many grains, gluten itself is notable in that it is actually fairly slow to digest, but also has the somewhat interesting ability to overwhelm the antigen-sampling sites in the small intestine. (Simply put- lining your gut are patches of cells that sample incoming molecules and sift out pathogens. Gluten has the ability, through an unknown mechanism, to bypass the normally controlled rate of pathogen sampling these cells have and “bombard them”, which is one reason why celiac symptoms progress so rapidly). However, for a healthy individual with no immune intolerance, gluten itself is an unremarkable protein.
For an athlete, there is absolutely no documented advantage to avoiding gluten or wheat. The arguments thrown about (fiber grains chelate, or bind, to iron, causing its loss… true, but all fiber does this… high grain diets cause malnutrition, yes, in populations not give other foods, etc.) are rarely backed by any real research or empirical data. If you can tolerate wheat grains, then you will not receive any performance advantage from avoiding them.
This progresses to the argument that humanity did not evolve eating grains, and therefore is not “made” to use them optimally. This is true, but misleading- humanity evolved as an obligate omnivore, able to adapt rapidly to changes in diet. Prehistoric man rarely had the luxury of a steady food source, and hence developed the ability to adapt to many kinds of food. Bear in mind that gut flora and fauna adapt to new diets within years, not thousands of generations, so grains themselves are no more foreign to humanity than many kinds of nuts or new world fruits. It is also naïve in the extreme to believe that modern day fruits and vegetables have anywhere NEAR the nutritional profile of wild grown plants tens of thousands of years ago (even organically grown ones), or that modern farm cows have the mineral content in their meat that wild game did back in our ancestor’s time (This point is relevant because it illustrates the limitations of attempting to duplicate historical diets).
And this all ignores two other major facts as well: 1) One of the leading causes of death in paleo/neolithic times (next to trauma or infection) was malnutrition (and they typically died long before they aged to the point where many modern afflictions could trouble them, hence the low rates of heart disease etc.), and 2) Human ancestors had a tremendously wide variety of diets across the globe, from the pure, high fat animal diets of the Inuit peoples to the low protein, high in vegetable and grain (wheat and barley) diets of certain east Asian late paleolithic/early neolithic tribes, so attempting to determine any “historical” human diet is futile.
So this brings us to: is a “Paleo” type diet (avoiding grains and “processed food”, focusing on meats, nuts, fruits, and vegetables) good for an athlete? The answer- it can be in theory, but rarely is in practice. Not because Paleo itself is a bad concept- far from it. All athletes can benefit from focusing on whole foods, vegetables, meats, nuts, and the like… but when done at the expense of carbohydrate sources and when this involves the arbitrary elimination of certain foods, performance is likely to suffer. Certainly not all Paleo diets are low in carbohydrate, but it is easy to underestimate how many fruits and vegetables an individual would need to take in to fuel extended exercise. The instinctive avoidance of “processed” foods can also be a mistake. Certainly, there is reason to be marginally suspicious of certain food additives, but the author does recall a laughably ignorant video where the individual being interviewed was decrying “chemicals” like guar gum and carrageenan. The amusing reality behind these two “chemical” thickeners is that they are, respectively, a naturally occurring fiber in guar seeds and the fiber extracted by boiling seaweed. Nothing unnatural about either, and can be extracted with little more technology than a hammer and bowl of water! An alarming name does not necessarily indicate an alarming compound.
So, bottom line, “Paleo” diet is neither good nor bad in and of itself from a performance perspective– eating whole foods is excellent, and fruits and vegetables are high in vitamins and minerals, while refined flour is comparatively lower in both (though it is often enriched). However there is no inherent performance gain from adjusting one’s diet in this way, and no magical mechanisms by which these diets will improve body composition, boost one’s metabolism, reduce water retention, etc., so one is better served simply following basic diet rules that get them towards their goals. When in doubt, look at what the top athletes do.
A final note: For those interested in learning more about Paleo diets, there are MANY different takes on the Paleo concept. Much like any diet system, there are resources that are of absolutely stellar quality, and others who are simply trying to sell something. To be sure, there are many individuals who have had excellent results using this sort of diet system, and the reader is encouraged to keep an open mind. It is simply this author’s finding/opinion that the majority of athletes will not receive an inherent PERFORMANCE advantage switching to this sort of diet. General health considerations should be discussed separately.
Eating for performance part 1- Macronutrients (Source matters less than you may think)
Brown rice versus white rice. Whole wheat flour versus white flour. Skinless chicken breast versus skinless chicken thigh. London broil versus veal shank. Steel cut oats versus instant oatmeal. The former food item in each of these is typically considered the “healthier” alternative. Yet the difference between the former and the “unhealthier” latter? Next to none. Between the two there are insignificant differences in vitamin/mineral content, fiber content, speed of digestion, fat content, and so forth. So why the focus on the former? Because they sound healthier, most likely. Yet your body does not care whether a particular glucose molecule came from a pixie stick or a bowl of brown rice, or if amino acids came from a protein shake, a protein bar, or a piece of raw tuna. Provided one’s diet contains adequate vitamins, minerals, and fiber, the source of the macronutrients is truly inconsequential.
So what matters? First, the macronutrients themselves.
Protein: A good guideline is, as a rule, 1g/kg of bodyweight. 0.8 grams per kilogram is the recommended daily value established by the FDA, generated by observing large populations over time. Exceeding this with the rationale that activity level is higher in the athlete is reasonable. And the upper limit? As mentioned in another article, patients hospitalized with significant burn injuries (who are shedding body proteins at an incredibly rapid rate, close to ten times the rate of a healthy yet protein starved individual), are typically put on diets rarely exceeding 3 grams of protein per kilogram of bodyweight. This may seem exceptionally low to some, particularly strength athletes who are used to taking in 2-3 grams per POUND of bodyweight, but is the reality.
Bear in mind there is no real reason to avoid exceeding this (patients with end stage renal failure notwithstanding), and certainly a triathlete taking in 5000 calories a day is likely to exceed this even when eating balanced meals. Which means protein intake is usually the least of an athlete’s concern. And complete versus incomplete? Not as big a worry as some may claim. Biological value, protein efficiency ratio, and all the other terms thrown around are a primary concern if a protein source is one’s ONLY protein source. However, even gelatin (considered an incomplete “garbage” protein), can be combined with other incomplete garbage proteins to supply the body with every amino acid it needs. Simply put, as long as you have a few protein sources in your diet, you likely do not have to worry about amino acid ratios.
Fat: It’s been said over and over again that the body needs fat, and this is no myth. Essential fatty acids are considered essential for a reason- they are used in various critical bodily processes, but the body lacks the enzymes needed to synthesize them from other sources. If you’re not getting EFAs from fish, avocado, canola oil, wheat germ, etc., it may be worth considering supplementing with fish oil tablets (3-5 grams a day). Beyond this, it’s worth noting that special effort need not be made to AVOID fat. Despite years and years of recirculating bad science, there is still no definitive link between saturated fat and heart disease, so animal fat need not be avoided. For the average athlete, 1g/kg of fat is fine for optimal health and activity- more will convey no advantage (yes, fat and cholesterol are a precursor to androgens, but more cholesterol does not equal higher testosterone).
One interesting item worth mentioning- fat prior to endurance exercise has actually been shown to improve performance significantly (in longer distance events). For marathoners, half iron or iron distance triathletes, century cyclists, and similar individuals, it may be worth experimenting with pre-workout fats (I would recommend peanut/almond butter, avocado, or mixed nuts). The amount should be kept relatively low (0.25g/kg, taken 2-3 hours beforehand) to avoid GI upset.
Yet is there a NEED to take in x grams of fat? This author would argue no, the quality of the fats taken in are far more important than the overall volume. 0.5g/kg of bodyweight would likely (given existing clinical data) not hinder the average individual in the least.
Carbohydrates: The real focus of performance nutrition should be around carbohydrates and timing of their intake. Generally speaking, if adhering to the roughly amounts of each other macro listed above, the remainder shoulder generally come from carbohydrate sources. But what sources?
As mentioned earlier, there’s far less difference between many carbohydrate sources than many seem to realize- whole grains in general have little nutritional advantage over more refined grains, and even many sugars are far more equal than the general media seems to state. (For example, even the much-reviled high fructose corn syrup (HFCS) is nutritionally identical to table sugar, and within seconds of entering the digestive tract the disaccharide in table sugar is quickly broken down to the two monosaccharides in high fructose corn syrup.) Waxy maize, marketed under various brand names (including the UCAN brand targeted towards endurance athletes) is essentially corn starch, and has no special properties- one may as well consume mouthfuls of flour or grits. So what DOES matter?
Generally speaking, higher fiber carbohydrates DO satiate longer, particularly when consumed with other nutrients. Athletes should almost never consumer carbohydrates on their own during their standard meals; fats and proteins do more to slow gastric emptying than does the inherent “glycemic index” of various carbohydrate sources. The exception to this is immediately prior to and during exercise- immediately prior to SHORT duration activity, many individuals can benefit from a quick carbohydrate top off from simple sugar sources, in the neighborhood of 0.5g/kg/hour of activity. Note if consumed more than half an hour before activity, the system will release a large amount of insulin (as activity level will be low but blood sugar high) which will negatively impact performance, so it is critical this be done within a short window of activity start.
During activity, athletes benefit from carbohydrate AND protein sources, as carbohydrates alone can cause both GI upset and hinder fluid uptake. (The mechanism for this has to do with how water is absorbed in the gut- both sodium and several amino acids are used as exchanges for water molecules in the cells lining the GI tract, and without amino acids in the gut it is difficult to hydrate properly… leading to sugars remaining in the gut and not being absorbed either). My recommendation for long duration athletic activity is 0.75g/kg/hour of carbohydrate and 0.25g/kg/hour of protein (from either branched chain amino acids or easily digested whole food sources like milk or whey), in conjunction with adequate fluid.
Following activity, provided one’s diet is on point, the post-workout “anabolic window” does not truly matter. If an athlete has been consuming sufficient calories before and during a workout, then any regular meal within several hours of activity should be sufficient.
So to sum up, regarding carbohydrates, what guidelines should an individual follow?
1) Avoid eating carbohydrates on their own during normal meals
2) Only consume simply carbohydrates on their own IMMEDIATELY prior to activity
3) During activity, consume simple carbohydrates in conjunction with a small amount of protein
4) Carbohydrates should still constitute the majority of an athlete’s diet, as low carbohydrate levels during activity are far more detrimental to performance than low protein or fat levels.
5) There is no hard and fast rule regarding whether or not carbohydrates should be consumed at night. The only critical point to remember with carbohydrates is that, in general, the “harder” to digest they are (i.e. the less refined), the further IN ADVANCE of exercise they should be consumed.
The general gist thus far has been that source does not matter terribly much, for ANY macronutrient. So the last piece is the actual caloric intake.
Eating for performance part 2 – Overall calories
There are NUMEROUS formulas out there that can be used to calculate caloric intake. The best formula? Simply record your weight, spend the next week recording your EXACT intake, weigh yourself one week later, and figure out what the net gain or loss was from that total. Why? Because though the human body operates according to a basic set of rules, energy expenditure can be infinitely complicated. Activity level is nearly impossible to predict, and arbitrary calorie figures can be dramatically off. 20 calories per kilogram of weight may be a great basal rate, times 1.5 for moderately active days or 1.75 for heavily active days, but sleeping in an extra hour can decrease your daily requirement by 100 calories or more, depending on your size and lifestyle. Taking a flight of stairs one day and not the other, or wearing heels one day and not the other, or having too much coffee and twitching your leg for 2-3 hours while at your desk and not the next… these can all undermine the most carefully calibrated calorie count. The best gauge is the scale, followed by performance. Simply focus on the protein and fat macros above (at a minimum), include additional carbohydrates to fuel performance as needed, and fill the rest of your diet with enough calories to reach your daily average. When cutting weight, reduce the total by 10-15% (maintaining those basic minimal macros), when trying to gain weight, increase the total by 10-15% (from any source).
ANY attempt to make this more complicated is as likely to fail as it is to succeed. There are no diet secrets, there are no superfoods, there are no underground metabolic accelerator techniques, there is no such thing as “starvation mode”, there is no such thing as “stoking your metabolism through frequent feedings”, there is no such thing as ghrelin/leptin “manipulation”. When given a system with infinite variables, a simple model that uses 3-4 HIGHLY RELEVANT variables is no less accurate than a complicated model that uses 20-30 potentially relevant variables. Period.
The final installment will contain a review of various diet systems, as well answer the numerous diet questions that have been received from readers after the first article.