I'm far from a guru, but I see no need to increase calories too much higher above the level which you were consuming whilst on, due to the fact of a lowered nutrient partitioning effect (as you said) as well as an overall lower demand for calories..
This is the way i look at it, purely my own opinion and it could be completely wrong and false but here goes...
The way I see it, when you're "on", your body can absorb, utilize, and process X amount at any given time.
I think of being "on" as your body utilizing calories to maintain, repair, rebuild itself, and partition nutrients in a favorable way, at a rate of say 100 liters per day
When you're off, that number decreases, down to say 60l/day, along with the ability/efficiency of the body to partition calories favorably etc etc.
Considering the fact that your body doesn't quite have the same efficiency of repairing muscle tissue, partitioning nutrients and possibly has a slower metabolic rate in comparison to what it once did whilst "ON", adding in excess calories, more than what's required would almost defiantly result in fat gain.
What would i do: Maintain your current Calorie intake, maybe increase protein intake just for peace of mind, Take pictures, measure gym performance and then go from there.
Its largely trial and error.
When im off I have to reduce my intake of carbs and fats slightly as I'm a fatty and get soft quickly with too many cals, but protein either increases slightly or stays the same.
Just my .02c and how i look at things.
I'm happy to be educated on the topic also, always new things to learn.
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