Let's talk gainers 101
Though energy surpluses are NOT necessary for muscle gain with several studies reporting gains in LBM during hypocaloric conditions , they do create a more optimal, anabolic environment for growth along with facilitating intense training in the gym. Thus it should be a “given” that if seeking to OPTIMIZE gains in LBM a slight sustained calorie surplus will do the world of good
HOWEVER gains in LBM are far slower than gains in fat mass & unfortunately, those who try to force feed muscle growth with hefty surpluses and/or 1500kcal mass gainers only end up with additional fat gain with NO additional muscle gain vs those who adopt smaller surpluses . This then causes a problem as, mechanistically, fat tissue play no role in aiding LBM growth, in (quite the opposite) thus, by unnecessarily increasing your BF%, you reduce your muscle:fat ratio & impair the effectiveness of your bulk .
Who are gainers for? Gainers are ONLY every for those who have miniscule appetites or extremely large maintenance requirements whereby they can’t physically EAT enough to still be in a SLIGHT surplus. Liquid kcals are considered less satiating than solid, largely due to their short oral residence time thus gainer shakes are POTENTIALLY useful in this case. Furthermore, in terms of convenience, for those without ANY access to food for LONG periods of time (lol you must live in a desert then), meal replacement shakes can be handy however again, there is no reason as to why you can’t then just MAKE YOUR OWN with WHOLE FOODS which is a far cheaper, more versatile & sometimes tastier alternative (my YouTube vid recipe has 825kcal which is hefty enough as it is)
Who are then not for? Anyone who loves food & can easily create a slight surplus with whole food. Also, for anyone with HUGE appetites, gainers are completely pointless & instead, eating more solid, higher volume, low energy density foods will aid in decreasing hunger & desire to eat.