The following was written hastily and any failure to empathize and ‘remember the human’ in my writing is due to a shortage of time and bandwidth, but I hope that it will be read with the understanding that I respect you @The_Cog, and don’t intend to disparage you as a person. I want to tread carefully here because it takes a great effort to attend to respectful and empathic debate, while stating claims and any refutations clearly. If there is any disagreement, or sharpness of tone, it is because of content and approach, and not because of you personally.
I’ll bow out of this discussion here after this post, for reasons of bandwidth.
I chose my words carefully. I was refuting the absolutism of your claim.
I said “open for debate” because you said “It should be noted that such fine-grained recommendations are not really research-based,” which feels very absolute.
Asking for citations to support one side of the debate when I’m claiming that at least the debate should be allowed to be open, based on researcher opinion, and not citations, feels a bit like a strawman.
As in, it feels like you misunderstood my position and misrepresented it, or chose to misrepresent it, which is understandable, because I sometimes do use very circuitous language, and for that, I apologize.
If either of those are not true, I suspect it’s me not quite understanding what claim you are attempting to attend to by asking for citations in response to my assertion about researcher opinion.
There are none. My claim was based purely on personal conversations I have had with researchers and athletes. I should have clarified that.
This feels a wee bit like ad hominem, given my profession. (Sport physiologist PhD, specializing in fueling and hydration strategy during endurance exercise). In case you were not aware that was my profession, this would not be ad hominem. But I suspect you are aware, given your knowledge of my recent company venture and my long posting history on related topics in this forum. To claim that a researcher has not read the literature in their particular field when they are stating that they have, is a bit sharp.
In any case, rest assured that I have reviewed the literature.
In fact, I have long used internet forums like this one as a place to test my ideas about the literature against a relatively willing combative or intentionally contrarian audience. I appreciate you engaging and apologize if it feels like baiting. I did not intent to bait here, but rather to clarify what I viewed as some claims that were stated too strongly and absolutely.
You chose one paragraph to cite which made things sound equivocal, but left out something important that immediately followed:
Conclusions
…gut-training or feeding-challenge around exercise may provide advantages in reducing gut discomfort, and potentially improve carbohydrate malabsorption and Ex-GIS, which may have exercise performance implications.
What you cited pertained only to a few of the physiological mechanisms these researchers reported on in the abstract.
More globally, when several studies find no results from something, and other studies find some results, it doesn’t mean the research findings are equivocal. If that were true, then virtually all interventions, including training, would be found to be equivocal because there are countless studies finding no improvement in fitness ability after various training protocol. You just never read those studies because nobody shares them or talks about them. And lots of those types of studies just never get published because it feels sheepish as a researcher in exercise science to have designed a test protocol that does nothing and then to publicize it, if the goal of the researcher was to tease out differences between protocol.
Study design and statistical power limitations are the bane of sport science’s existence, and there are virtually always studies that point to either side of any debate.
In something as new of a concept as gut training for increased carb absorption during exercise, we can expect more than half the literature to fail at finding anything positive for a while. But careful review of all the literature I think paints a clear picture, as did the researchers of the review you cited.
I’m not sure I feel comfortable going study-for-study with you for the following reasons:
- You imply I haven’t reviewed the literature.
- You misuse and cherry-pick quotes from citations where the authors come to the opposite conclusion you’re trying to make. When cherry-picking, which is sometimes useful, and I’m not saying I do it well, it is important to at least provide rationale for why a quote is chosen and others are ignored.
- Bandwidth reasons. (see company discussion below!)
No. Our app has several settings which can actually limit the carb amounts to below the amounts recommended in the literature. This is critically important for folks who don’t have much experience in higher carb fueling, who simply prefer a lower carb approach, or who have blood sugar dysregulation, metabolic disease of some kind, or substantial history of body composition struggles.
In fact, the most common report from our users is not that they’re surprised by how much carb they should be consuming, but rather that they’re surprised by how much water and sodium they need.
I do have a financial interest in people believing that there is something to be gained from personalization of carb, sodium, and water intake, and that it doesn’t have to be a huge amount of math to get things optimized because an app can do it for you.
If you’ll allow me, I’d like to bask in your profit motive claim as a major compliment, if I may. If feels like the time I was accused of wearing a 50 pound pack on Strava when I took a descent KOM from someone. Kind of like ‘you know you’ve done something special when…’
It’s the little things like this that really keep a guy going when there is not yet profit (yes, there is income, just far short of profit). 
It’s the first time someone has claimed “profit motive” as an argumentation tactic in debate with me, and I’ve sort of been waiting for this moment as a marker of “we’ve made it onto the radar” as a company.
So, thank you.
I humbly posit that my posting history on this site and others long predates any notion that I would someday create an app that helps people fuel. And I think I’ve been very consistent in my stances, or very clear when they’ve changed and for what reason. I’d encourage you to review my stances on carbs, sodium, and water, over the years, as I’ve made them very public in this forum and others. I’ve been an ardent adherent to what is in the literature (science), and the synthesis of available real world experience with that literature. I attempt to be pretty clear on what basis I am standing on, whenever I make a claim. When I am not clear on my bases, I can always be asked to clarify, and am purely attempting brevity (and failing badly at it, as I have here) by not always stating the basis on which I stake a claim.
Here is a clarification on my view on gut training:
Gut training works, it is unequivocal. That was my original comment here. But, that does not mean it is the primary thing people need to be focused on. They should focus on implementation strategy. It turns out that getting folks to do gut training is one way that companies are selling more powder, because what it’s actually doing is getting folks to focus on practicing implementation of higher carb strategies more often, in the name of gut training.
More than 90% of fuel & hydration issues come from problems of implementation, and not intrinsic limits in gut absorptive ability. And if you want a statement from me that really drives people to purchase an app that customizes fuel and hydration details for you, then there you have it. 
Please feel free to claim profit motive. I have no way of untying my company from such a statement because it underlies our core vision and mission.
