Sources:
Aragon, Alan Albert, and Brad Jon Schoenfeld. “Nutrient Timing Revisited: Is There a Post-Exercise Anabolic Window?” Journal of the International Society of Sports Nutrition 10 (January 29, 2013): 5. https://doi.org/10.1186/1550-2783-10-5.
Schoenfeld, Brad Jon, Alan Aragon, Colin Wilborn, Stacie L. Urbina, Sara E. Hayward, and James Krieger. “Pre- versus Post-Exercise Protein Intake Has Similar Effects on Muscular Adaptations.” PeerJ 5 (January 3, 2017): e2825. https://doi.org/10.7717/peerj.2825.
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 (December 3, 2013): 53. https://doi.org/10.1186/1550-2783-10-53.
Schoenfeld, Brad Jon, and Alan Albert Aragon. “How Much Protein Can the Body Use in a Single Meal for Muscle-Building? Implications for Daily Protein Distribution.” Journal of the International Society of Sports Nutrition 15 (February 27, 2018). https://doi.org/10.1186/s12970-018-0215-1.
There are some interesting wrinkles (like Leucine intake in particular), and I'd recommend looking at what Stuart M Phillips and Donald K Layman have published as additional places to spelunk from for anyone that's particularly interested in the topic.
Plus if you're training but want to lose at the same time, you need a caloric surplus for a while to have your muscle regenerate and grow, but it's totally possible to gain muscle and lose weight at the same time. But basically each calory that you're in deficit will make your muscles grow more slowly, so it's definitely harder than being on an overall surplus.
I also heard somewhere it could take like 24~48 hours for all protein sources to be digested and extracted from your bloodstream so you might have like a constant amino acids drip into your bloodstream but i never really checked this.
> Or is this less important than the immediate-protein-shake crowd suggests?
From what I've read, this may be not as important as originally thought.
Overall, I believe the schedule that most holistically supports metabolism would be to exercise early and also eat early in the day. This would thereby keep the taxing metabolic activities aligned to your circadian clock, which expects a lot of early day stressors and fewer as the day progresses. This may be specifically true for protein which is especially metabolically taxing, so eating it early in the day is probably the time when it creates the most benefit at lowest risk.
Of course, people have to do what works for their schedules and lifestyles.
This is slightly contrary to what I’ve learned from Rhonda Patrick. Exercise in the morning, sure, but while still fasting from overnight (black coffee or plain tea ok… does not break the fast).
Eat after exercise so that your fast lasts longer. Also, cardio exercise blunts the hunger feeling in many people.
Now, I don’t know what effect all that has on other metabolic processes. I doubt the effect is universal. But it is interesting that the revived wisdom about black coffee being okay is not universally true.
There's apparently some significant variation between people. Some don't see a glucose spike at all, some see it vanish if they consume protein first, and some see it regardless.
(Ie if you had pumped the liquid directly into her stomach, without telling her whether it's black coffee or some substitute, would the outcome still have been the same?)
Something I wonder about though is that if blood glucose is rising after black coffee, that energy must becoming from somewhere. i.e. stored fat, stored glycogen or stored protein.
Given that she's about do some fasted exercise that will burn that blood glucose as its fuel source, is this a bad thing if the energy is coming from stored fat?
For a healthy person, this might be good. For someone with various health issues (like the person in question), I don't know.
Wouldn’t the glucose have to come from somewhere?
A continuous glucose monitor checks the level of glucose in your blood. Glucose can be stored in your body as glycogen (e.g. in the liver, or muscle tissue).
Your pancreas produces glucagon, which influences the process of converting it back into glucose, released into your blood.
That's generally accepted basic science, but from my own anecdotal friends/family experience, the pancreas also seems like a pretty buggy organ generally, prone to glitches both temporary (like perhaps in this coffee drinker) and chronic (type 1 diabetes), leading to undefined behavior, crashes, and even fatally bricking the system permanently.
So this anecdote isn't particularly surprising to me.
(Also, for those reasons, I would definitely wear a continuous glucose monitor myself if it wasn't so expensive and difficult to arrange when you don't actually have anything known to be wrong with your blood sugar levels. I predict that within a decade or two, they will be a fairly ubiquitous piece of human body instrumentation, like the sleep-tracking wristwatches and rings we have today.)
But is there a difference between having your day's large meal at 8am or 11am? Those are both pretty 'early', so it might not matter; I don't think we know. However, as the day winds on, more data comes to light which suggests that earlier is better.
I have not seen studies like that. All the ones I’ve seen have participants stop eating 3 hours (minimum) before sleep. For example, With an 8 hour eating window and 10:00 sleep, that means eating between 11:00-7:00 giving you a 16 hour fast.
This study in particular looked at early TR (6am-2pm) vs mid afternoon (1pm-8pm) TR vs no TR; and early TR had the greatest metabolic benefits by a long shot:
> "Furthermore, eTRF (early TR), but not mTRF (mid-day TR), improved fasting glucose, reduced total body mass and adiposity, ameliorated inflammation, and increased gut microbial diversity. No serious adverse events were reported during the trial. In conclusion, eTRF showed greater benefits for insulin resistance and related metabolic parameters compared with mTRF"
My caloric window is 1-8pm and I exercise in the mornings with just a few essential amino-acids.
Ive spent a lot of heartache and headache over research around these type of questions. The best answer is to learn what works best for your own body. Eat enough protein as a starter in any case.
My understanding is that protein can be rate-limiting for hypertrophy if you don't have enough in general, but timing is not as largely important. I believe there is a rough window for anabolic signaling / net-positive muscle protein synthesis that lasts up to 48 hours after exercise