I am always unsure how this applies to someone with an irregular exercise schedule. If, when fasting (intermittent) my exercise is primarily cardio then I will continue fasting. However if it is resistance training, does getting some protein into my system as soon as possible take priority over fasting? Or is this less important than the immediate-protein-shake crowd suggests? Should I try to pull the window forward if exercising early?
A few researchers, notably Alan Aragon and Brad Schoenfeld did a lot of analysis on protein timing research a while back and the general conclusion is that as long as you get enough protein during the course of the day (or within a few hours of your workout), basically it doesn't matter so much.
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.
This makes more sense than "you have to eat protein within one hour from exercising". Why? Because wouldn't it take a lot longer for the protein to get digested in your body? Possibly many hours, depending on the source of protein. And if, after exercising, I'm still digesting protein I've eaten several hours earlier, what difference can it make if I add some more that will just get digested several hours later, provided that the total amount of protein is kept constant.
This has mostly arrived in the consensus of sports training. General advice is to have protein surplus in the 24 hours after training (if you train every day, like an athlete, that means every day).
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.
Yes Don Lyman's research has shown the same thing. Timing of protein consumption doesn't matter very much. The important thing is to consume a large bolus of at least 40g during a single meal rather than spreading it out in little snacks throughout the day.
After doing a 4 hour eating window for years eating at around maintenance and had some cheat meals over the weekend. It kind of kept my weight stable but my strength hardly increased so seems my anecdotal experience kind of seems to match that report.
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.
I'll assume that your goal when drinking a protein shake/gaining muscle is to gain muscle. It's generally believed that a state of anabolism is generally viewed as being antagonistic to the body; too much protein/growth is taxing. Yet, having muscle is important for aging, and also acts as a glucose sink thereby improving metabolism. A balance has to be achieved.
> 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.
Here’s a piece of COMPLETELY anecdotal data, so do with it what you will. A friend with metabolic syndrome was struggling with weight despite intermittent fasting. She began to wear a continuous glucose monitor. She found that black coffee had the same effect as eating a donut, but if she added a boiled egg, the effect on her glucose was neutral.
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.
That's pretty crazy. I wonder if placebo effects played a role?
(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?)
The easy test would be to see if it's the caffeine having this affect by using switching between caf and decaf.
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?
> Give that she's about do some fasted exercise that will burn that blood glucose as it's 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.
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.)
This has been my schedule for my entire adult life, not because I read it, but simply because it felt the "best" for myself. I was never a big breakfast eater anyway, and I found fasted + black coffee exercise the best for myself personally in terms of energy, motivation and so on.
My girlfriend pretty consistently gives me grief about it, as it goes against what she's been taught/knew. But I've always felt better doing physical or mental effort fasted, at least for a few hours in the morning!
Yeah I'm not suggesting an order between the two. I think everything held constant, eating earlier is supposed to be better. I don't think there have been many studies where people stop eating at like, 10am, or something like that. That said, I think most studies that have shown benefit are those where people have like a 4-8 hour eating window from 6am-2pm, or are of that order.
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.
> 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.
Here is the study I am referring to [1]. As far as studies go, this one is fairly rigorous and of what I would consider to be high quality based on several factors related to the study design.
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"
Proteins have 4 calories per gram so if your usual post-workout protein intake would be 20-30g, it'd be 80-120 calories. YMMV but that would move me out of fast. The only calories I ingest during the fast is a little fat for vitamin D bioavailability in the morning.
My caloric window is 1-8pm and I exercise in the mornings with just a few essential amino-acids.
Protein thermic effect is 30% so amount of calories equal to ~30% of that coming from protein is burned to digest protein. You're burning calories, not protein, to digest protein. Those calories are already stored and don't necessarily have to come from protein digestion.
No. I do IF and lift heavy+cardio every early morning. I have progressively gotten stronger - benching over 330 and squatting well into the 400s.
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.
I can't comment on fasting in particular, but as another comment pointed out, I think the idea that you need to immediately get protein before/during/after a workout is a bit overblown.
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
The 'anabolic window' has largely been disproven. Depending on your goals though, from a resistance training perspective you typically need to be in a caloric surplus (although not an excessive one) to put on muscle.
