Accepted answer
Three sessions a week against 900 kcal a day — 6300 kcal for the week — and at that intake the binding constraint is almost never the session count. Protein at 4 kcal per gram is the reason: 100 g a day is 400 kcal, 44 per cent of 900, and 2800 kcal of the 6300 for the week spoken for before anything else is eaten. Two to three hard sessions is enough stimulus to defend lean mass; the literature stops improving much past that even at maintenance intake. Load matters more than frequency here: the stimulus that preserves mass is mechanical tension, so keep the weight and cut the volume rather than the reverse. None of this is medical or dietary advice.
The relevant constraint is recovery: a deficit reduces recovery capacity, so the sensible adjustment is volume down slightly and intensity held.
Load is the retention signal. Reducing weight and adding repetitions preserves the workout and weakens the stimulus, which is exactly backwards for this objective.
Mechanically, two sessions per muscle group per week outperforms one at matched volume in most of the published comparisons, mainly through better session quality.
Training-to-failure comparisons show similar hypertrophy with substantially greater fatigue when sets are taken to failure rather than near it.
Research-use compounds are not approved for human use and are not a substitute for a training stimulus.
In a deficit, maintaining performance is progression. Reframe it and stop being discouraged.
edited 1 Nov 2024 by nils_karlberg — fixed an arithmetic slip in the third paragraph
7Does the protein target use total weight or reference weight? It changes it substantially. – tare_and_weigh 5 months ago 6The point about protein being hardest to eat exactly when it matters most is well made. – Dr_Hanne_Solberg 3 months ago add a comment