Introduction 7

Definitions and Basic Background 8

What is protein? 8

Where is dietary protein found? 9

Amno acids: The building blocks of protein 10

What is protein used for in the body 11

Complete and incomplete proteins 11

Protein Digestion and Absorption 12

Step 1: Digestion in the mouth, stomach and small intestine 12

Step 2: Liver metabolism 13

Step 3: Release into the bloodstream 14

Efficiency of protein digestion 16

Speed of digestion 17

Fast and slow proteins 18

Absorption speed of other proteins 21

Explaining the contradiction 22

The impact of previous meals on digestion speed 22

Is faster digestion better? 22

Is there a maxvnum protein intake per meal? 23

Summary 24

Basic Protein Metabolism 25

Protein turnover: The link between protein synthesis and breakdown 25

How eating affects protein synthesis and breakdown 26

Diurnal cycling 27

The effects of training on protein metabolism 27

Summary 29

Protein Requirements 35

How should protein intake recommendations be given? 35

Protein turnover and nitrogen balance 37

Athletes and protein requirements 39

Problems with nitrogen balance 40

Solving the controversy? 42

Protein needs during dieting 43

Female protein requirements 44

Protein Quality 45

Methods of measuring protein quality 45

Biological value (BV) and Net Protein Utilization (NPU) 47

Protein efficiency ratio (PER) 49

Protein digestibility corrected amino acid score (PDCAAS) 49

Summary 49

Amrio Acid Requirements 50

Determining maintenance AA requirements 51

Growing vs. non-growing subjects and protein requirements 52

Exercise and AA requirements: Introduction 56

Endurance exercise and AA requirements 56

StrengttVpower training and AA requirements 57

Dieting and AA requirements 60

Summary 64

Meal Frequency 65

Meal frequency and health 66

Meal frequency and body weight/metabolic rate 66

Practical aspects of meal frequency 66

A quick reality check 67

Meal frequency and nitrogen balance: direct research 68

Summary: Direct research 69

Optimal meal frequency: A theoretical approach 70

Is it possible to eat too frequently? 70

How long does a meal maintain the bod/ in an anabolic state? 72

Summary: Theoretical examination of meal frequency 72

Protein distribution throughout the day 73

Is there an optimal intake pattern for different goals? 73

Nutrient Timing Around Workouts 75

The interaction between carbohydrate and protein 76

The pre-workout meal 76

Immediate pre-workout nutrition 78

During workout nutrition 80

Post-workout nutrition 84

Glycogen resynthesis: Introduction 84

Glycogen replenishment with at least 24 hours between workouts 85

Carbohydrate and protein postworkout: improved glycogen synthesis 86

Nutrient timing and body fat 95

Application 96

Protein Controversies 97

Kidney function 97

Bone health 98

Metabolic acidosis 99

Colon cancer/heart disease/overall health 99

Summary 100

Whole Food Proteins 101

By way of introduction 101

Fowl 101

Fish 102

Red meat 103

Legumes: Beans and nuts 109

Soy 110

Other proteins (grains, vegetables, fruit, etc.) 112

Food allergies and intolerances 112

Summary 113

Protein Powders 115

Dairy: Whey, casein and milk protein isolate 118

Soy isolate 121

Other vegetarian proteins: Pea, rice and hemp protein 122

Supplements 123

Glutamine 124

Tyrosine 126

Branched chain amino acids/leucine 126

Application 128

Essential amino acids (EAAs) 129

Application 130

Creatine monohydrate 131

Potential negative effects of creatine supplementation 133

Application 134

Carnitine 135

Application 136

Acetyl-I carnitine (ALCAR) 136

Application 137

Carnosine/beta-alanine 137

Application 138

Taurine 138

Application 139

Citrulline malate 139

Application 139

Arginine/ornithine/glutamine 139

Application 140

Application 141

4-hydroxyisoleucine 141

Application 141

Bovine Colostrum 141

Application 142

Summary 145

Putting it All Together 146

Sport categories 147

Sporting goals 148

Losing body fat: Introduction 161

Losing body fat: Specific recommendations 161

Gaining mass: Introduction 163

Gaining mass: Specific recommendations 163

Female athletes 165

Vegetarianism 166

Appencfx 1: Protein intake Tables 169

Appendix 2: Determining Protein Cost 172

Source for data: Layman DK. Baum Jl. Dietary^- protein impact on glycemic control during weight loss. J Nutr. 2004 Apr:134(4):96SS-73S

Related to this, one study that gave wrestlers massive amounts of BCAAs (0.9 g/kg or 63 g/day for a 70kg individual) found a slightly greater sparing of LBM and a greater loss of visceral fat (34). This study is discussed in more detail in Chapter 12 but it's important to note that the protein intake of the wrestlers was not very high, approximately 80 grams per day or less than one-half of what this book would recommend. Whether additional BCAAs would be beneficial given sufficient protein intake in the lirst place is unknown but seems unlikely.

The high concentration of BCAAs and especially leucine in whey protein makes it attractive on a diet (additionally, the cysteine content may have a beneficial effect while dieting, as discussed in Chapter 12). However, recall from Chapter 2 that casein exerts an anti-catabolic effect due to its slow rate of digestion; this should be beneficial on a diet. Milk protein isolate, containing both whey and casein might be an ideal protein for dieting; empirically it also seems to keep dieters full better than other protein powders.

In one of the only relevant studws I'm aware oC overweight police officers received either whey or a casein hydrolysate along with a reduced calorie diet and resistance training. The casein group lost significantly more body fat (7 vs. 4 kg) and gained more muscle (4 versus 2 kg); this suggests that the slow digestion rate of casein may make it superior on a diet due to its anti-catabolic effects.

With respect to glutamine supplementation while dieting. I'm only aware of one study. It provided a high dose of glutamine (0.35 g/kg or 24 grams for a 70 kg person) to w restlers on a large caloric deficit, no effect on LBM sparing was found (35). Glutamine would appear to be ineffective as an anti-catabolic compound: ensuring adequate protein and BCAA intake on a diet would seem to be the superior strategy to limit lean body mass loss.

Summary

Arguments are commonly made regarding ihe superiority of one protein over another in terms of supporting mass gains or sports performance. To examine this topic. 1 first looked at the issue of maintenance requirements in terms of AAs (rather than just total protein).

With regards to maintaining current levels ofbody protein, it doesn't appear that any one protein is superior to any other: all high quality dietary proteins are well in excess of even the highest estimated AA requirements for tissue maintenance.

Due to the energetics of endurance training, an increased need for BCAAs, glutamine or both might be postulated. Given the high level of BCAAs in most dietary proteins, as long as endurance athletes obtain sufficient high quality protein (1.7-2.0 g/kg for men and 1.3- 1.6 g/kg for women), BCAA requirements should be covered. There is at least one study suggesting that additional BCAA intake might be of use even within the context of sufficient protein intakes.

In contrast to endurance athletes, strength/power training doesn't use protein for fuel. However, glycogen depiction from training could conceivably increase BCAA breakdown (and hence requirements) and increases in lactic acid might conccivably increase glutamine requirements. Outside of those two AAs, the increased protein requirements arc generally required to cover the synthesis of new proteins as well as the breakdown of damaged tissue that occurs with training. There is little to no indication that any specific AA profile will be required to support this process. Ensuring sufficient high quality protein (along with sufficient energy intake) would appear to be sufficient.

Limited data examining different types of protein supplementation on strength and size gains tends to support this idea: quantity is more important than protein quality, especially with large intakes of varied protein. At the 2.5-3.0 g/kg (1.1-1.4 g/lb) of protein recommended in this book, with that protein coming from a variety of high-quality sources, within the context of maintenance or higher caloric intakes the AA profile of individual proteins should be completely irrelevant.

During dieting, there is an increased use of protein for energy and this serves to increase overall protein requirements above baseline. Recommendations are given in Chapter 4 and discusscd again in Chapter 13. Ensuring sufficient BCAA intake during these periods may exert an anti-catabolic effect with dairy proteins (casein and whey) being high in BCAAs and especially Icucinc. Milk protein isolate, containing both casein and whey may be an ideal protein during dieting.

Meal Frequency

In this chaplcr, I want lo look at the issue of meal frequency and protein intake during the day. Bodybuilders are probably the most obsessive of all athletes when it comes to eating protein (and calorics) in small amounts throughout the day (often eating every 2.5*3 hours or so) with the belief that this is necessary for optimal protein utilization, growth or fat loss.

A typically given reason is that the body can only utilize some fixed amount of protein per meal. As discussed in Chapter 2, there may be an element of truth to this idea. An additional goal is to maintain a relatively constant level of amino acids in the bloodstream by ingesting small amounts at frequent intervals.

To one degree or another, most sports nutrition books echo the recommendation for a high meal frequency and there is certainly a significant amount of data to suggest that spreading one’s daily calories across more meals has health benefits. However, it’s less clear whether a higher meal frequency actually results in differences in how well or poorly the body utilizes nutrients and protein.

First I want to look at some of the potential benefits of a higher meal frequency throughout the day before looking at what little direct data on meal frequency and nitrogen balance exists. Finally I’ll look at the topic from a little bit more of a theoretical/physiological standpoint to try and reach some conclusions about optimal meal frequency and protein intake.

Meal frequency and health

There are a number of potential health benefits to spreading out calorics throughout the day (although some intriguing recent research, which is outside the scope of this book, is finding that intermittent periods of fasting can also have benefits).

Spreading daily calorics out into several meals (usually called a "nibbling" pattern) as opposed to a few larger meals (often callcd a "gorging” pattern) has been found lo improve insulin sensitivity and carbohydrate tolerance (I) and leads to improvements in blood lipid levels (2).

It's important to note that many of the meal frequency studies use a somewhat unrealistic number of meals relative to real-world eating patterns. A typical study might compare a few meals per day to upwards of nine to 17 meals/day. Whether a difference between three to four meals and five to six meals will exist is debatable; some studies find a benefit of six versus three meals, others do not.

There is certainly generally no harm to spreading daily calories into smaller, more frequent meals (outside of possible convenience issues related to meal preparation) but there may not automatically be a benefit from a health perspective.

Meal frequency and body weight/metabolic rate

It is often claimed that higher meal frequencies cause weight loss and that lower meal frequencies (or skipping meals) lead to weight gain. Interestingly, early studies on meal frequency often found that eating more frequently led to weight gain (as opposed to the weight loss benefits often claimed) but this is likely due to the fact that individuals were adding snacks to their normal eating patterns. This is different than taking the same daily caloric intake and splitting it into multiple smaller meals.

Related to that issue, and in contrast to the commonly held belief, meal frequency has no real impact on energy expenditure given an identical caloric intake; eating the same number of calorics in a few small meals will cause the body to expend the same number of calories during digestion and metabolism as if they arc eaten in many smaller meals (3). The majority of studies have not found a major effect on weight loss (fat loss is less well studied) with varying meal frequency cither, at least not when caloric intake is identical.

Rather, it appears that any impact of meal frequency in terms of body weight loss has to do with changes in food intake, probably subsequent to changes in hunger and appetite (3). For example, studies have found that eating more frequently tends to reduce appetite (and thus spontaneous food intake) and this occurs in both lean (4) and obese individuals (5). If eating more frequently keep someone full and they end up eating less total calorics, they will tend to lose weight/fat. | But this is occurs bccausc they are eating less calorics, not bccause of the meal frequency per se.

In contrast, as noted above, some earlier studies found that eating more frequently causcd weight gain, and this was probably because it led to people eating more total food each day. If someone simply adds more food to their normal intake, and this causes them to eat more total calorics, this will result in weight/fat gain. But again, this occurs not because of the meal frequency per sc but in how the change in meal frequency is affecting total food intake.

Again, this is different than the suggestion to take the same daily caloric intake and spread it across more, smaller meals per day which, generally speaking, has been found to be beneficial in terms of fullness, blood sugar stability, and health.

Practical aspects of meal frequency

Regardless of potential health benefits related to meal frequency, there may be practical reasons to eat more or less frequently. For athletes with high caloric requirements, eating multiple smaller meals may make consuming sufficient calorics (and especially carbohydrates) easier to accomplish compared to eating a few' larger meals (6). example, endurance athletes generally have fairly high caloric requirements and cyclists and runners often report eating 8-10 times/day to meet them (6).

Large strength/power athletes can have similarly large food requirements and may need to eat more frequently to avoid the stomach upset that can occur with very large meals. Hating six 1000-calorie meals may simply be easier than trying to force down three massive 2000-caloric meals.

Conversely, individuals with lower caloric intakes (e.g. lighter female athletes trying to reduce body w'eight) may find that high meal frequencies make individual meals too small to be satisfying or filling. A light female who may be consuming 1200-1500 calories/day would probably find six meals of only 200-250 calorics each to be fairly unsatisfying. Utilizing a lower meal frequency, perhaps four meals of 300-375 calorics apiece, may be better in this case.

Another issue has to do with the amount of training being done. An athlete who is training 3-4 hours/day (elite cyclists may be on the bike for 4-6 hours/day during which time they do consume nutrients) and w’ho sleeps an additional 8-9 hours/day has a limited amount of time to consume a large number of calories. It can become practically difficult to eat a number of small meals w’hen the total time available for eating is limited; eating fewer larger meals may be the only realistic way to consume sufficient calorics to support a heavy training schedule. In contrast, a bodybuilder who may only train 1-1.5 hours/day may find that their training doesn't impact on their meal frequency at all.

A final practical consideration has to do with athletes or individuals w'ho work in addition to their training. Work schedules may or may not allow' athletes to fit in 6 small meals per day. So even if such an eating schedule is ideal, it may not be practically possible.

A quick reality check

Athletes often obsess about meal frequency, fearing that missing even a single meal will result in muscle or performance loss. Readers might recall from Chapter 2 and 3 that there are mechanisms such as storage ofprotein in the gut in place to provide the body with AAs during periods where food isn’t available. Additionally, in the very short-term, any proteins broken down when food isn’t available tend to come from labile proteins such as liver proteins prior to the breakdown of skeletal muscle.

Perhaps (he most direct evidence against the idea that going more than two to three hours without eating causes muscle loss has to do with the digestion rate of most proteins. As discussed in Chapter 2. most proteins digest relatively slowly. Consider, for example, lhal roughly 40 grams of casein protein may still be releasing amino acids into the bloodstream seven to eight hours later.

The fastest digesting protein is whey, which appears to digest at roughly 10 grams/hour and that only holds for whey consumed by itself under fasted conditions; adding other nutrients slows digestion. In any case, if an athlete consumed 40 grams of whey protein, it would take 4 full hours to digest; almost any other protein would take longer than that. The idea that any time period longer than two to three hours will cause the body to enter a catabolic state simply makes no sense given these facts.

As a singular example, one study found that a relatively modest whole food meal containing 75 grams of carbs. 17 grams of fat and 27 grams of protein was still releasing amino acids and other nutrients (glucose, fatty acids) into the bloodstream at the five hour mark (7); clearly providing more nutrients sooner than that was not necessary to keep the body "fed". Others have suggested that a given meal will continue to exert an anabolic effect on the body for at least five to six hours (8).

An additional point that readers might want to consider is this: over the normal sleeping period of 8 or more hours, the body is generally unfed. Yet an athlete's muscles don't fall off during that time period due to the lack of food intake (I'd mention again that the body stores protein following meals that are released during the fasted period). The idea that a single missed meal, or going longer than three hours without eating will result in gross catabolism of muscle tissue makes no physiological sense.

However, none ofthe above tells us whether a higher frequency ofprotein intake would be more or less optimal in terms of muscle mass gain, adaptation to training, or the maintenance of muscle while dieting.

To further address this topic, I first want to examine what little direct research exists on the topic of meal frequency and nitrogen balance.

Meal frequency and nitrogen balance: direct research

While there is no doubt that health and practical issues are important to the Issue of optimal meal frequency, none of that information addresses the specific issue of how meal frequency or timing might impact directly on protein utilization, muscle growth, sparing lean body mass loss on a diet, or recovery per se. Surprisingly very little research has been done, most of it is about 30 years old, almost all of it used nitrogen balance and almost none of it has been done in athletes or individuals in training. This makes extrapolations to athletes difficult at best.

For the most part, a majority of studies have found no significant difference in terms of nitrogen balance using a variety of meal frequencies (in these studies, protein and caloric intake was kept constant). However. I'd bring up again that the nitrogen balance method is problematic at best and inaccurate at worst, so it's difficult to draw' strong conclusions from the following research.

In one early study, subjects were put on either three or six meals with an identical protein and caloric intake: no difference in nitrogen balance was found (9). The same study also examined the issue ofprotein distribution throughout the day, studying a group that was given 25% of its protein at breakfast and at lunch and 50% at dinner: again, no difference in nitrogen balance w'as seen (5). I'll discuss the idea of distributing protein differently throughout the day later in this chapter.

Another study examined the effects of changing meal frequency in women and examined meal frequencies of three, two or nine meals per day: no differences in nitrogen balance were seen (10). In another study, young men were given 1800 calories and 118 grams of protein and cither one, three or six meals/day: no differences w'ere seen in terms of nitrogen balance, wxight loss or fat loss (II). The same group looked at nutrient utilization under the same conditions and found that one meal w'as inferior to three or six meals but no difference w'as seen between three and six meals (12).

In contrast, a more recent study found that six meals/day led to slightly greater w'eight loss and slightly better nitrogen retention in women on a 1200 cal/day diet compared to only three meals per day (13). Another study, which gave 800 cal/day and 13-15% protein (25- 30 g total protein per day) found that five meals w'as superior to three meals/day in terms of nitrogen balance, but there were no differences in weight or fat loss (14). Please note that 25-30 grams ofprotein per day is not only below' the RDI for protein but also far less than what is required to limit LBM losses while dieting as discussed in Chapter 4.

In possibly the most commonly cited paper on meal frequency and weight and muscle loss, boxers were put on 1200 calories/day w'hich was eaten in cither two or six meals per day; while both groups lost muscle the higher meal frequency group lost less (15): this is often cited as proof that a higher meal frequency is superior to lower frequencies while dieting but I find this conclusion to be somewhat flawed.

The main problems are that the study used liquid meals and gave inadequate protein to both groups. Had solid meals (w'hich take longer to digest) or adequate protein been given, I suspect that the results would have been different. Additionally, I consider a two versus six meal comparison somewhat artificial; I suspect that three versus six meals (w'ith solid foods and sufficient protein) w'ould have shown no difference in results.

Beyond the study in boxers above. I’m unaware of any research in training humans that has examined the impact of meal frequency on the adaptations to training. It’s possible that research on sedentary individuals simply doesn’t apply. Perhaps by increasing the rate of protein turnover, the body needs protein more frequently when individuals are training than when they aren’t. These are simply unanswered questions.

However, one very recent study has examined this topic although the data has only been presented in abstract form (i.e. the full paper is not yet available). Thus any results should be considered extremely preliminary. The study could have had methodological flaws that negate the results; without being able to read the full study, there's simply no w'ay to

know. However, since it's some of the only direct research into this topic, I want to least present the results in their preliminary form.

In that study, 33 men and 15 women with at least one year of previous resistance training were placed on either a three or six meal per day diet (16). The three and six meal per day groups were instructed to eat the same number of calories, providing a roughly 300 calorie per day surplus wilh protein intake set at 1.7 g/kg. Compliance to the diet was measured by self-reporting of food intake.

Both groups performed the same training program over 12 weeks and changes in body composition and body weight were measured. Contrary to what is most commonly believed, the three-meal group gained both more weight and more total LBM.

The reasons for this result are obscure although I'll examine some of the possibilities below. Given the greater total weight (and body fat gain), it may simply be that the three meals per day group simply ate more total calorics (the researchers tried to account for this in their statistical analysis). Given the impact on meal frequency and appetite described above, this seems reasonable. As well, although calories were set at identical levels between the groups, self-reported food intakes are often inaccurate: even slight differences in food intake over the length of the study could have significantly impacted on the results seen.

However, as I'll discuss below, there is some evidence that it is possible to eat too

frequently which might limit protein synthesis. It’s conceivably that the 6 meals per day

group crossed this threshold, leading to the observed results. Once again, without being able lo read the full manuscript, there's simply no way to know. As well, the results will

need to be replicated before any strong conclusions can be drawn.

Summary: Direct research

At calorie balance and given adequate protein, it appears that a higher meal frequency has no real effect on nitrogen balance, at least not in non-training individuals. The exact impact of training on this issue is essentially unstudied: I'll discuss the topic of nutrient timing around training in detail in the next chapter. Which isn't to say that there might not be other reasons of practicality or convenience lo adopt one meal frequency over another.

From a practical standpoint, as mentioned above, an athlete wilh a 6000 calorie per day caloric requirement may find it easier to cat six 1000 calorie meals instead of three massive 2000 calorie meals. Dividing up protein intake across each of the individual meals seems the most logical approach. Athletes with much smaller caloric requirements often find that fewer (but relatively larger) meals are more satisfying and filling.

During dieting, or when protein intake is inadequate, some studies suggest that a higher meal frequency may have benefits in terms of preventing lean body mass loss. Given the apparent impact of different AA levels on prolein synthesis and breakdown (discusscd in Chapter 2), this makes some sense. Maintaining relatively even levels of amino acids in the blood should help to limit muscle catabolism by decreasing protein breakdown.

Combining a higher mcal-frequcncy wilh slowly digesting proteins would most cflcctivcly accomplish this.

In the boxer study, for example, with only two meals (and liquid meals at that) and insufficient protein to begin with, the body had no source of protein for most of the day; we might expect it to break down body protein under those conditions. With the addition of a third meal, or more total protein, or a slow digesting protein (such as casein or milk protein isolate), the results might have been far different.

How meal frequency affccts lean body mass gains with a caloric surplus is essentially unstudied although one preliminary report found that a group consuming three meals per day gained more lean body mass than a group consuming the same calorics and protein in six meals per day. As the full paper has not yet been published, the exact reasons for this are unclear.

However, as I discuss below, it's theoretically possible that eating too frequently might actually be detrimental from the standpoint of stimulating protein synthesis.

Optimal meal frequency: A theoretical approach

In Chapter 3, I discussed how eating impacted on both protein synthesis and breakdown following a meal. To briefly recap, an increase in blood AAs primarily stimulates protein synthesis with a much lesser impact on protein breakdown; in contrast, increasing insulin levels appears to primarily decrease protein breakdown with only a small impact on protein synthesis. With that information as background, I now want to examine the topic of meal frequency from a slightly more theoretical standpoint by examining two separate questions:

1. Is it possible to eat too frequently?

2. How long will a typical meal maintain the body in an anabolic state?

By determining a potential maximum and minimum amount of time that should pass between meals, an optimal meal frequency can be developed. As well, I want to examine the idea that different meal frequencies might be optimal under different conditions (i.e. maintenance versus mass gains versus dieting).