Does Protein Timing Really Matter?

TAGS: protein synthesis, nutrient timing, nighttime nutrients, anabloic, Scott Stevenson, anabolic

Let’s Get Logical

If you’ve read my first few articles here at elitefts™, you got a glimpse into some of the confounding scientific issues surrounding the phenomenon of peri-workout nutrient timing. While there is reason to cast scientific doubt on the importance of peri-workout nutrition(1, 2), the strategy also has scientific supporters(3, 4), decent studies in support of timing alone per se(5, 6)), and a sound physiological basis(7).

It was physiological reasoning that led Dr. Thomas Fahey to investigate the idea of intra-workout “feeding” nearly twenty years ago(8, 9) (and why I starting training with intra-workout concoctions many years ago). The idea is simply to provide nutrients to promote adaptation when the adaptive process is occurring most rapidly(10-12).

It’s a Lifestyle

Competitive bodybuilding is sometimes considered a “lifestyle” because of the belief that optimal progress requires ‘round the clock effort. Recovery is a 24/7 process. For example, outlandish caloric intake in the off-season lends itself to eating frequently(13). Frequent meals(14) with careful attention to protein intake(15) may also aid in retaining precious muscle when dieting down for a competition. Bodybuilders also dot their i’s and cross their t’s with a multitude of nutritional supplements(16, 17), often using more of them as contest day nears(18), even to the extent of risking health in some cases(19).

All Day… And All Night?

If we’re microanalyzing the day’s events, one rationale for intra-workout nutrition might be to simply reverse the inhibition of protein synthesis(20, 21) and loss of glycogen(22) during exercise. A one or two hour workout is ~4-8% of the day: extrapolated out over years of training, we could be talking about missing out on pounds of muscle mass here, right?

This same perspective–albeit perhaps a bit neurotic in the above example–holds more water when we consider the potential “time lost” on the anabolic clock over the course of an typical night’s sleep. Naturally, this has led many a bodybuilder to consume slowly digesting “night-time” protein (typically casein(23)). Some of my brethren have even gone so far as to prepare bed- or toilet-side protein shakes to keep the anabolic mojo movin’ (not to mention setting an alarm to wake for this nighttime meal).

Is this just maniacal, compulsive behavior gone awry, or are there data supporting the effort to “stay anabolic” at night?

In Case You Didn’t Know…

You might be thinking about rule of thumb set out by Adelle Davis: “Eat breakfast like a king, lunch like a prince, and dinner like a pauper(24).” A bodybuilder’s correlate might be to use a “carbohydrate cut-off,” which typically means limiting food to meats and vegetables at some point late in the day. Setting aside the possibility that the above strategy might not make sense if one also trains late in the day (this leads us back to peri-, specifically post-workout nutrient timing), the first question worth answering is, “Can a (large) late night meal or ‘nighttime’ casein protein provide a prolonged provision of amino acids?”

The simple answer is, “Yes.” In Boirie et al.’s oft noted study(23), 43 grams of casein (just the protein) provided prolonged amino acid entry into the blood stream, positive leucine balance (suggesting a muscle building effect) and an inhibition of protein breakdown over seven hours of measurement during which nothing else was eaten (as would be the case if sleeping). Whey protein (30 grams, to match Leucine content) was absorbed much more rapidly, thus stimulating protein synthesis as well as amino acid oxidation initially, but, over the entire seven hours, did not favorably affect protein breakdown or overall protein “accretion.”

You see, unlike whey, casein forms a “clot” in the stomach(25) and contains casomorphin proteins – natural opiates that reduce gastrointestinal motility(26, 27). Another perk of casein for those who are dieting is that it seems to be a better appetite suppressor than whey(28), which might help with nighttime hunger pangs.

“Faster” acting proteins like whey and soy have their place. During the three hours post-exercise, whey appears more anabolic than soy, and both beat out casein(29). If we extend that “window” to four hours post-workout, whey and casein appear equally anabolic(30). However, over an eight-hour stretch, milk protein (~80% casein(31)) delivers more amino acids (and leucine) than soy to the peripheral tissues (think muscle here)(32). (For your info, milk or milk protein seems to beat soy, too, as a peri-workout supplement for adding muscle mass(33-35).)  At the risk of giving seed to ludicrous ideas, Boirie’s group also demonstrated that spreading a 30 gram protein dose out over 13 mini-feedings also generated a positive leucine balance over seven hours(36). I’d stick with the casein, however, if you want a good night’s sleep.

Big Eats Before Bed?

How about just a big old meal? Might this be a way to prolong nutrient provision over the course of a night’s sleep?

Generally, how long it takes for food to empty from your stomach is a matter of how many calories you’ve eaten(37) and is slowed by fat(38-40). In one study, an all (Italian-)American pizza meal of 600kcal (75g carbohydrate, 37g protein, 17g fat) had only delivered about 60% of its carbohydrate content to the body after 5 hours. Less than 40% of the amino acids (<15g protein) were actually delivered to the peripheral tissues during this time period.  For a normal-sized person, it may take about four hours for half of a buffet-style breakfast of about 7-800kcal (~40g protein, ~32g fat) to empty from the stomach(41). On the other hand, a slightly smaller breakfast (522kcal) that is lower in fat may deliver essentially all of it’s nutrients to the body’s tissues within five hours(42).

So, depending on the bodybuilder, his size, what he’s eaten previously, and what and when his last meal of the day is, it’s possible that there could be a few hours of “down time” for the anabolic night train in the wee hours of the morning. Even an 8PM final meal, followed by breakfast at 6AM means ten hours between “feedings.” So, what do the studies show when it comes to packing in the protein (and food in general) before bedtime?

Nighttime Nutrient Timing

The casein nighttime protein strategy, when actually consumed at night, after a day of regular eating and a late day workout, does seems to pan out. After an 8PM workout and a 9:30PM recovery supplement (20g protein/60 g carbs), a 40g casein dose just before bed (midnight) does indeed improve protein balance during the night’s sleep, compared to a non-caloric placebo(43).

Another “timing” study actually gives the nod to nighttime protein over taking it pre-workout, at least when it comes to using casein. (See comments above about “fast” proteins post-workout.) Using a cross-over design (subjects underwent both conditions), waiting to take their second daily dose (35g of an 82% casein supplement) just before bed (10:30PM), rather than pre-workout (4:00PM), meant significant gains in fat-free mass that also correlated with increases in squat strength. The authors suggest that taking the nighttime protein could, “prolong the duration of moderate aminoacidemia each day and lead to an increase in protein deposition and fat-free body mass over several weeks(44).”

Won’t I Get Fat?

Well, when it comes to this nighttime strategy, there are not reams of data to go by, but it seems that shifting your day’s calories, especially carbohydrates (but not fat) towards the end of the day may very well be to your advantage. Another cross-over study found that when the calories of a weigh loss diet (combined with exercise, of course) were shifted toward the end of the day (70% of kcal split over dinner and a hearty “evening snack”), subjects oxidized fat better and lost more body fat. Perhaps more importantly, eating more later in the day meant better retention of fat-free mass(45). Israeli researchers designed a diet to modify leptin levels (and thus satiety) by lumping most of the day’s carbohydrate in at dinner time. While leptin manipulation didn’t turn as they had hoped, late day carbohydrates meant greater weight loss, improved cholesterol and insulin levels, better glucose tolerance, greater satiety, and reduced markers of overall body inflammation (46).

Although the mechanisms haven’t quite been worked out, this pattern of shifting food and/or carbohydrate towards the end of the day seems to promote “metabolic flexibility(47).” (Metabolic inflexibility characterizes diseases of diabetes and obesity that fall under the umbrella of metabolic syndrome(48).) In the weight loss studies mentioned above, the advantage of metabolic flexibility manifested itself quite simply as the ability to utilize body fat (not muscle) for energy when dietary calories are in short supply. (This is a good thing.) Speculating that circardian (night/day) control of metabolism might also be involved(49-51), Bray et al. predicted that mice eating a high fat, low carb chow early in the day, but switching to low fat, high carbohydrate food at night would fare better than mice eating in the reverse pattern. Indeed, the mice eating low carb/high fat meals for “breakfast” grew up leaner, with better glucose tolerance and blood lipids, and were better able to oxidize dietary fat, even while metabolizing those late day carb meals(52).

What Time is It?

If the purpose of nutrient timing is to match nutrient provision to the metabolic demand of recovery, taking in a hearty dose of protein and carbohydrate in general before bed makes perfect sense. As I’ve mentioned previously (check out “Are You Training Enough?”), muscle protein synthesis is elevated for about ~24 – 48hr after a weight workout (53-55). However, if you’ve been working out for a while, this protein synthetic response is reduced(56, 57), and the anabolic effect of a training session may be over and done with in only 16 hours(58) if you don’t continue “feeding the machine” with an influx of nutrients(59). So, the time you spend spend sleeping the night after a workout is prime time for gaining new muscle mass.

Additionally, for those who work out later in the day, shifting carbohydrate and protein intake towards the night “works out” quite well: This strategy ends up being a double-whammy of both ”nighttime” and post-workout nutrient timing.  Eating a “low carb” early in the day also gives opportunity for healthy fat intake [low in trans-(60), high in omega-3(61, 62), conservative in saturated fats(63)], and a dietary pattern that seems to promote the health and body composition benefits that characterize metabolic flexibilty(52).

Practically speaking, some people simply find that low carb meals improve mood(64) or “energy” throughout the day, but that post-workout carbs are also something to look forward to. There may also be reason to favor carbohydrate post-workout, in addition to protein, especially if you train with a high volume.  The more work you do, the more glycogen you use(65). A workout can potentially create such an energetic demand during recovery(66, 67) that even 1000 grams of carbohydrate may not refill glycogen stores over the 24 hours post-workout(66) if you’ve created a good deal of muscle soreness and damage(68-70).

Those of you who keep a box of protein bars on your nightstand, or have a bathroom, sink-side mini-bar stocked up with MRPs may have been nodding your heads a lot when reading this article. However, if you are now thinking you might have been left in the dark when it comes to nighttime growth opportunities, what are you waiting for?  Your best bodybuilding progress may await you in the (satiated) nights to come.


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