I have been doing OMAD for over a year and a half, and also cycling the Kcal and macros.
Except for the high kcal days, which can be every 4-5 days (in my last block), I have rarely reached 2500 kcal, in fact much less. So a low kcal intake we already know what it entails both on a cosmetic level and on a muscle mass level, but I feel very comfortable being on those 4 low days and increasing the 5 for example. I’m able to keep my gains, my weight and my body fat low.
More than the digestion of a large meal that reaches those kcal (2,500 for the example you give), it affects me more how my body manages this high amount, and consequently how the insulin is able to distribute it efficiently and in the right places, either in a single balanced in their macros, as higher in protein, moderate amount of fat and low amount of carbohydrates, as each of the distributions will report different hormone cascades.
My experience tells me that my body is better able to handle low amounts of calories and food than high ones, and every certain period of time, spike the calories and their macros, and more than protein and fat, the carbohydrates.
In the last weeks I’ve been doing the high kcal day test, doing 2 spaced meals and the result is optimal, but I need to go back OMAD to at least a few days, where I feel much more efficient.
More than feeling psychologically better with more meals, it is the need to add more macronutrients, micronutrients and reach some caloric goals that allow me to continue progressing with the feeling of wellbeing and digestive relaxation that OMAD gives me.
The sensation of an empty and relaxed GI does psychologically produce a sense of well-being.
But you are right, that sources of protein such as whey and eggs should facilitate the process, I think that also white fish or pork loin, have an easy digestion. Even add 1 serving of Mag10 to the Plazma during training.
The goal would be to find a way for my digestive and hormonal system to be efficient in processing at least 2.2 grams of protein per Kg, as well as to find a base with carbohydrate and fat intake that will allow me to maintain my current body composition and body mass and I am sure that this increase after a strict OMAD will help me to progress or even improve my condition.
I am not obsessed with adding muscle mass, but with the structure I have, to have a very good package and quality.