In ITP and other lifespan trials I typically see the intervention is placed in the food.
I wonder about a confounder of taste: since caloric restriction works well, would putting bad tasting stuff in the food seem to produce a lifespan extension that is actually just the mice eating less because it tastes bad?
I wonder this about NAC which tastes terrible, and had good results combined with glycine in one trial.
Is amount of food eaten measured to reduce this confounder in eg ITP?