If young, active guys lift weights 4 days a week and eat the same total amount of protein, it doesn’t matter whether they have their casein protein late at night or earlier in the day — they’ll gain similar muscle and strength over 10 weeks.

If young guys who lift weights drink a protein shake with 35 grams of casein every day — and keep training — they could gain about 2 to 2.8 kilos of muscle in 10 weeks.

For young guys lifting weights, eating 1.8 grams of protein per kilo of body weight each day is enough to gain muscle and get stronger in 10 weeks — it doesn’t matter if they take a 35g casein protein shake during the day or before bed.

If fit people already eat a lot of protein, taking extra casein protein in the morning or before bed doesn’t change their body fat or muscle over 8 weeks—if their workouts stay the same.

Drinking a protein shake with casein before bed helps your muscles grow and get stronger while you sleep, especially if you're working out.

If you're someone who works out regularly, adding 54 grams of casein protein to your daily diet—whether in the morning or at night—won’t make you gain fat over 8 weeks, even if you don’t change your exercise routine.