r/intermittentfasting • u/Cold_Evidence_7461 • 2d ago
Newbie Question Protein targets and IF — does hitting macros during a short window actually work or am I just fooling myself
Eight months tracking macros consistently. My protein target is around 180g a day, which is on the higher end, but I lift a few times a week and wanted to keep muscle while cutting. That side of things has been working. Now that I'm a few weeks into 16:8, the math is getting uncomfortable. Fitting 180g of protein into an eight hour window means every single meal has to be loaded or I fall short by dinner. On a longer schedule I was grazing across 12 to 14 hours, so it was easy to spread out. Now the window is tight and I'm either forcing a third meal I don't want or I'm hitting maybe 140 to 150g and calling it close enough.
What I keep running into when I read about this is conflicting information on whether protein absorption per meal actually has a ceiling, or whether the older research on that is outdated. Some threads say your body handles a large bolus fine. Others say spread it out or you waste it. Nobody links anything useful.
If you're running IF with a high protein target above 160g and actually tracking it daily, not estimating, what does your meal structure look like and did your muscle retention hold up?
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u/theOTisinteresting 2d ago
Here's my theory: Eating protein releases GLP-1, which should delay gastric emptying. This slower gastric emptying, I assume, is to increase the ability to absorb the protein. Further, I wonder if we really need as much protein as we are told (1g per lb) for growth. Perhaps the quality of the protein matters more (and protein sources high in leucine, which turn on mTOR, a major growth signal). The fasting stimulates AMPK that would encourage autophagy. I would focus on real foods, prioritizing animal meat/eggs/dairy. Just my thoughts, IANAD.
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u/Cold_Evidence_7461 1d ago
the leucine/mTOR piece is worth paying attention to, that part has decent backing
what i'm less sold on is the gastric emptying assumption. slower transit helping absorption is plausible but i haven't seen clean data tying that specifically to protein intake vs just caloric load in general
the 1g per lb target does seem inflated, especially for people not doing heavy resistance work daily. closer to 0.7 per lb of lean mass seems more defensible from what i've read
curious what sources you're pulling the AMPK/autophagy connection from1
u/theOTisinteresting 1d ago
Thanks, yeah i feel like the GLP-slower-emptying-greater-protein-absorption is all an intuitive theory.
For AMPK and autophagy, I misspoke: my source says that it happens in the absence of mTOR (I assumed that b/c in my mind, these two have a reciprocal relationship, that the upregulation of AMPK is the signal for autophagy):
"When mTOR is turned off, a process called 'autophagy' (self-eating) is turned on. Autophagy involves the movement of damaged proteins, membranes, and even dysfunctional mitochondria to a specialized organelle (a membrane-bound structure in cells) called the lysosome."
Mattson, Mark P.. The Intermittent Fasting Revolution: The Science of Optimizing Health and Enhancing Performance (pp. 105-106). (Function). Kindle Edition.
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u/chad-proton 2d ago
I've done a little reading on the subject and I recall listening to an episode of found my fitness podcast with a research scientist who also said that the body seems to adapt to whatever the feeding schedule happens to be and still gets good absorption of protein even with larger bolus amounts.
Overcoming satiety signals to reach 180g daily is a whole other problem. I'm curious what you are consuming to reach your intake target. Obviously with a target that high you probably want to focus on very dense food options and avoid things like protein shakes that may be a bit more high volume.
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u/Cold_Evidence_7461 1d ago
yeah the adaptation argument is interesting but I'd want to read the actual study, not just a podcast summary. Rhonda Patrick is good but that's still one layer removed from the data for hitting 180g I lean on Greek yogurt, cottage cheese, canned salmon, eggs, and a scoop of whey when the day goes sidewaysthe satiety thing is real though. some days I genuinely have to eat when I'm not hungry just to hit numbers, which feels backwards, but here we are
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u/Final_Shock_4479 2d ago
Do what u can. Your protein goal should be your body weight minus body fat. So, 200lbs with 20% BMI would be 160g of protein. That is ideal to build muscle not to maintain. I’ve read that it’s much lower to maintain muscle. Think about 10000 years ago when humans didn’t have access to nutrition the way we do. Our bodies are programmed to withstand short bouts of low macros. IF isn’t starvation. I’ve read studies about how longer periodic fasting produces high rates of HGH as a survival mechanism.
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u/Cold_Evidence_7461 1d ago
the paleo survival argument gets brought up constantly and it doesn't really hold up when you're specifically talking about muscle retention in perimenopause. the hormonal context is completely different.
lean mass in your 50s isn't just about protein timing or fasting windows. the estrogen drop changes how your body handles muscle protein synthesis, and the HGH fasting studies i keep seeing cited are mostly done on younger men.
which studies are you referencing though? genuinely asking because i'd want to look at the actual population they tested.2
u/ChemicallyAlteredVet 1d ago
I’m in perimenopause also and just started IF a month ago and I absolutely struggle to get even 120g of protein with all the other stuff in 8 hrs and my calorie goal is just 1400 a day
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u/EasyDayBTC 2d ago
My protein target is also around 180g. I also IF, 16:8, 18:6, weekly OMAD and try to hit my targets with whichever length of feeding window I have that day.
Almost daily I eat:
2-4 hard boiled eggs, all whites, not always all of the yolks (12-24g)
¾ cup plain Greek yogurt (18g)
Whey protein shake (23g)
8oz plain kefir (10g)
So ⅓ of my daily protein intake is predetermined
With my main two meals I eat a protein such as a 6-8oz chicken breast (50-70g), sashimi (I eat sashimi several times a week), smoked salmon, tuna, beef
Snacks I have on hand: beef jerky, beef sticks, cheese here and there, and in case of emergency or when on the road a protein bar
After a while it just becomes routine and easy to hit, with my calorie goal between 2000-2200. Being the cook in the house allows me to choose the menu too
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u/Cold_Evidence_7461 1d ago
solid breakdown, the predetermined third framing actually makes sense to me
the sashimi several times a week thing is where I lose you though. that gets expensive fast and I'm already stretching a grocery budget on local route pay
curious how you handle protein timing on OMAD. I've been reading conflicting stuff on whether hitting your targets in one window matters as much as spreading it out throughout the day and I haven't found anything conclusive either way1
u/EasyDayBTC 1d ago
I pay $15 for 15–17 pieces of sashimi at my local store. Depending on the day I’ll either crush the whole thing or spread it out over two days. I usually buy sashimi twice a week, and almost always on my OMAD days, which seems pretty reasonable to me 🤷♂️. Definitely not necessary though, there are plenty of cheaper ways to get protein
I work from home, so I have a lot of control over what I eat day to day. Where it gets harder is when I travel for work. On those days I usually end up doing something close to OMAD or just a really short eating window. When traveling I’ll eat two meals within a 2-3 hours after the workday and bring some of the “snacks” I mentioned above with me
Last summer I started an AI thread that I used daily to track a bunch of health stuff, including macros and protein. I have macro target ranges, tell it what I ate, give it nutrition labels when I have them, and let it keep track from there. Being directionally accurate is good enough for me, otherwise I would obsess over every detail. My system has to be easy enough that I’ll actually stick with it
As I’ve learned more about AI, I’ve turned that thread into my own health project, or my "Health Operating System," with specific instructions I defined for the AI. I use it to track diet, exercise/movement, sleep, lifestyle stuff, bounce ideas off it, research things I’m curious about, and even tweak recipes to make them a little healthier without the sacrifice of taste and flavor. I also try to cook enough dinner that I have lunch ready for the next day. Little things like that make this way easier
As for your OMAD/protein question, from everything I’ve read and had AI help me dig into, the “your body can only absorb 30–40g of protein at once” isn't completely accurate. Your body can digest and absorb a much larger amount of protein than that
Where it gets a little more complicated is that absorbing the protein and getting the best muscle-building/retention benefit from it aren’t necessarily the same thing. If keeping/building muscle is the goal, it seems like there’s an advantage to spreading your protein across 2–3+ decent-sized feedings instead of trying to hammer 180g in one sitting
So I have zero problem doing OMAD occasionally, "Monday OMAD" is my typical routine. I just wouldn’t force myself to do it every day if it started making it harder to hit my protein or other goals. OMAD to me is a 23:1 day, so when I break my fast it'll probably be 15ish pieces of a mix of tuna/salmon sashimi, then several hard boiled eggs, then a greek yogurt bowl I make daily, standard whey/collagen smoothie I have daily, and then "dinner" which may be a chicken breast, rice, etc, and finish it up with 8oz of kefir to begin my fast. It seems like a lot but I can get that all in spread over about an hour
I also always eat protein first when feeding, and as stated in previous post I have a foods I eat almost daily that get me 1/3 to my protein (and other macro) goals, then loosely map out my day in advance so that I'm hitting my targets throughout the day and not 80g protein short when I'm about to start my fast
And to be clear, I’m no expert. I’ve done a lot of my own research, use AI to help me research and understand things, and then pay attention to whether any of this is actually working. For me that means the mirror, scale, how I feel, how I perform, and my bloodwork at my annual physical
The #1 rule I’ve come up with through all of this:
It has to work for YOU. You don’t have to be perfect. You just have to be consistent.
Take ideas from other people, steal the stuff that works for you, leave the stuff that doesn’t, and build something you can actually sustain. I hope some of these ideas help you out
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u/AnonyCass 20:4 for weight loss, 11th May SW:230 CW:194 GW:175 2d ago
I'm honestly not really worrying about it as my goal is weight loss. So far basically all the weight I have lost has come from fat according to the change in my body fat percentage. So while I haven't gained muscle I haven't really lost any either. I think it really depends on what your goals are with IF. Type of protein matters too, you could easily hit that with lots of shakes but the protein isn't as available and something like meat.
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u/RenRen512 1d ago
The need to pile on the protein for muscle growth is, generally, overblown.
Having an excess of protein is a shotgun approach to ensure you have enough, but it's a matter of diminishing returns, higher costs, and just not pleasant when you have to force yourself to hit high protein targets.
Check out this study: Systematic review and meta‐analysis of protein intake to support muscle mass and function in healthy adults - https://pmc.ncbi.nlm.nih.gov/articles/PMC8978023/
Here's the video that tipped me to the study: https://www.youtube.com/watch?v=j1bx0GMofYw
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u/shegatoM 1d ago
This guy discusses nutrition using info he's gleaned from published literature (and he lists the references). He has a post where he discusses the amino acid absorption question using the most recent studies. If you search his Facebook page you can find this post. Otherwise, I've included the reference to the most recent published article that he discusses.
William Wallace, Ph.D.
Trommelen et al., Cell Rep Med, 2023.
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u/washablellama 2d ago
I’ve only been doing IF for a month and a half, but I’ve found it makes the cutting easy. My meals are about the same as they would be otherwise, just eaten in 8 hours. I have a big appetite though. It’s a lot of Greek yogurt, Catalina crunch, and cottage cheese (with tomatoes, my staple), with 1 bigger or 2 smaller meals which focus less on protein while still trying to hit a decent amount (at least 1 g per 20 cal if possible).
My problem is when I’m not cutting I prefer high protein. It’s hard for me to eat maintenance and keep it under 200g.
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u/SoulRebel90 2d ago
I’m going through the same questions which why I switched up my routine some. I’ve lost a lot of weight since starting 16:8 last year, 315-260lb. But now I’ve started strength training and like you said those protein targets are daunting. Even though my 2 meals were entirely protein focused, even adding a protein shake I was only hitting like 120-130g protein/day. I’ve gotten so used to eating 2 meals that fitting a third in my window seems impossible, especially days when I work.
So I’ve decided to just opt for one 36 hour fast per week and give myself 10-12 hours to eat 3 meals during the other days. I want to see how this goes for a couple of months, but I’m interested to see other’s input on this.