Protein-Timing & Fasting: Fasted Sprints & the Remarkable Muscle↑, Fat↓ Effect of Timing Whey With vs. Between Meals

Not sure what would happen to your sprints if you have whey before HITing it...
While more and more scientists and "evidence-based" trainers and fitness gurus, alike, keep repeating that "protein timing" - as heavily and feverishly as it is often debated on Facebook and elsewhere on the interwebs - is significantly less important than some gymrats still tend to believe (Schoenfeld 2013). The question "When do I take my whey shake?" is still a topic worth discussing. In particular, if an interesting new study - a systematic review, to be precise - seems to suggest that protein timing does, at least in protein supplementation studies, matter...

and what's most exciting, it seems to matter for the one outcome of physical exercise and dietary discipline many gymrats consider the #1 on their priority list: improvements in body composition... or, as many call it, "getting ripped and jacked" ;-)
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Now, while these results are somewhat surprising, they are not as counter-intuitive as the results of the 2nd study that made it into this "Meal-Timing & Fasting" special. The study I would like to begin with:
  • Sprinting fasted significantly increases time-to-exhaustion in trained cyclists (Terada 2018) -- If anything you would probably have expected that going into a sprint-interval session fasted, after an overnight fast (SITFast) would maybe increase the initial performance, because of elevated stress hormones, but the reality of a recent RCT (N=20) from the University of Alberta shows "that SITFast compromises exercise intensity and volume but still can have a greater impact on the ability to sustain high-intensity aerobic endurance exercise compared to SITCHO" (ibid.).

    The scientists had investigated the effects of sprint interval training (SIT) and exercising in the fasted state. To this end, they compared the effects of SIT with exogenous carbohydrate supplementation (SITCHO) and SIT following overnight fast (SITFast) on aerobic capacity (peak oxygen consumption: VO2peak) and high-intensity aerobic endurance (time-to-exhaustion at 85% VO2peak [T85%]).
    Figure 1: Fasted and without carbs, cyclists can train harder, but they are more enduring at submaximal, yet high (85%) intensities (ibid.).
    "Twenty male cyclists were randomized to SITCHO and SITFast. Both groups performed 30-second all-out cycling followed by 4-minute active recovery 3 times per week for 4 weeks, with the number of sprint bouts progressing from 4 to 7. Peak power output (PPO) and total mechanical work were measured for each sprint interval bout. 
    The SITCHO group performed exercise sessions following breakfast and consumed carbohydrate drink during exercise, whereas the SITFast group performed exercise sessions following overnight fast and consumed water during exercise. 
    Before and after training, V̇ O2peak and T85% were assessed. Blood glucose, non-esterified fatty acids, insulin and glucagon concentrations were measured during T85%" (ibid.).
    What the scientists found was (a) the expected reduction in total work done, i.e. that the "[o]verall PPO and mechanical work were lower in SITFast than SITCHO (3664.9 vs. 3871.7 Joules/kg; p=0.021 and 10.6 vs. 9.9 Watts/kg; p=0.010, respectively)", but also (b), i.e. that the baseline-adjusted post-training T85% was [significantly] longer in SITFast compared to SITCHO (19.7 ± 3.0 vs. 16.6 ± 3.0 minutes, ANCOVA p=0.038)" (ibid.).

    Plus the circulating energy substrates or hormones did not differ for the two conditions. Based on this and the previously mentioned results we can draw two conclusions:
    • Sprinting after an overnight fast (=AM fasted training) does not burn extra fat, but it burns less energy than doing cardio with a CHO supplement ⇉ for fat loss via sprint intervals, the additional CHOs - if accounted for in terms of 24h energy intake - are beneficial ('cause calories count ;-)
    • Your high-intensity endurance (surprisingly) benefits from training fasted and without additional CHOs to replete the loss of liver (and minimal loss of muscle) glycogen ⇉ It's yet hard to imagine a context in which this is actually relevant, though.
  • Having your protein with vs. between meals (as a snack) and thus extending the inter-meal fasting period may benefit your body composition (Hudson 2018) -- I am pretty sure some of you will remember this from the @SuppVersity Facebook News a few months (if not a year ago), where I have already addressed the study results based on the abstract of what was either a poster presentation or a conference talk, I believe.

    For their paper, Hudson et al. (2018) used the PubMed, Scopus, Cochrane, and CINAHL databases to identify those papers that had been published up to 2017 that described "randomized controlled trials of parallel design that prescribed a protein supplement and measured changes in body composition for a period of 6 weeks or more" (Hudson 2018).

    The carefully monitored reviewing process brought up a total of 34 randomized controlled trials with 59 intervention groups and their analysis showed that the subjects saw the following trends in changes body composition according to ingestion pattern:
    • Those who consumed whey with meals were less likely to gain total body weight (56% did), more likely to increase lean mass (94% did) and highly more likely to lose fat mass (87% did).
    • Those subjects participating in studies, where the whey was consumed in-between meals were more likely to see increases in total body weight (72% did), less likely to see increases in lean mass (90% did) and less likely to see reductions in body fat (59% did).
  • Based on these observations, Hudson et al. conclude that: "Concurrently with resistance training, consuming protein supplements with meals, rather than between meals, may more effectively promote weight control and reduce fat mass without influencing improvements in lean mass" (Hudson 2008).
    Figure 2: No differences in lean mass, but a "consistent" increase in body mass only in the inter-meal group, which also failed o see consistent decreases in body fat; consistent increases/decreases were defined as relative changes +/-  67-100% with ↑ indicating consistent increases and ↓ consistent decreases (Hudson 2018).
    According to the researchers' definition of "consistency" (67% to 100% change from baseline in either direction), though, both groups saw consistent increases in lean mass. The difference that they observed is thus related, mostly, to the effects on body fat, which was non-consistent in the inter-meal studies while it was highly consistent in the with-meal studies.

    As the authors point out, their deliberate exclusion of energy controlled studies doesn't allow us to say that this is a mechanistic effect beyond the mere reduction in energy intake on the main meals that may not occur when whey is consumed between meals. Bad news? Honestly, I'd say the opposite is the case: after all, this is the real-world, where perfect dietary adherence is the exception, not the rule.

    If it's not a decrease in total energy intake what's the advantage of not "snacking" whey... if this advantage actually exists?

    As previously highlighted, we cannot exclude that the effect was a mere result of reduced energy intake on the main meals. Nevertheless, there are at least half a dozen of potential other reasons that facilitate the higher rate of body composition improvements of the whey-with-meal studies (most from the excellent discussion of the results by Hudson et al.):
    • Whey = non-satiating snack - The whey shake that had to be consumed in-between meals may be seen as a mandatory snack of which previous studies show that they promote weight gain - especially if the snacks came in the non-satiating form of liquids (and yes, whey may be more satiating than coke, but let's be honest, it won't keep you satiated for long unless you spike it with something like xanthan to increase its viscosity | learn more about advantages of using xanthan).
    • Whey = possible replacement of regular dessert or simply reduction in meal size - Consuming the whey shake with the meal, on the other hand, may have the consequence that participants consume the (usually sweet) beverage instead of a dessert, instead of soda, or - because the spike in insulin, GLP1 and GIP gives them a temporary satiety boost - simply by consuming less on breakfast, lunch, and dinner, when co-consuming the whey protein shake.
    The exact mechanism, and whether and how significant any potential effects will actually be when you don't compare highly heterogeneous studies, but rather conduct a head-to-head (or shake-to-shake?) comparison of the effects of protein timing (i.e. ingesting whey with vs. in-between meals) should now be explored in an experimental follow-up study.
Hitting it After Weights - There are Downsides, but Systemically Impaired Strength & Size Gains are a Myth, Human RCT from 2016 Clearly Indicates | more
Bottom line: There are two things we should not forget. The first is something you can say about almost every scientific paper. Even if it is a systematic review and thus draws on available evidence from multiple experiments, its generalizability is never 100%. There are always exceptions to the rule and outliers. So, if you realize that you start snacking Snickers when you skip your inter-meal whey shakes, I would highly doubt that the body composition advantages will persist. In a similar vein, you must not forget that the endurance improvements with fasted sprinting will, to a large extent, depend on your ability to burn fat as fuel. If the latter is low, I would rather expect "bunking" (having to stop running early, because you are close to going hypoglycemic) than running "forever".

If you keep the previous caveats in mind and pay attention to the way your body, behavior, and quality of life(!) are affected by them, fasted sprints and whey with vs. whey in-between meals are two science-based 'bio-hacks' you may want to give a try | Comment!
  • Joshua L Hudson, Robert E Bergia, Wayne W Campbell; Effects of protein supplements consumed with meals, versus between meals, on resistance training–induced body composition changes in adults: a systematic review, Nutrition Reviews, (2018) - Ahead of Print at
  • Schoenfeld, Brad Jon, Alan Albert Aragon, and James W. Krieger. "The effect of protein timing on muscle strength and hypertrophy: a meta-analysis." Journal of the International Society of Sports Nutrition 10.1 (2013): 53.
  • Terada, T., et al. "Overnight fasting compromises exercise intensity and volume during sprint interval training but improves high-intensity aerobic endurance." The Journal of sports medicine and physical fitness (2018).
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