If you eat a scoop or two of casein protein before bed, it probably won’t change how hungry or full you feel the next day — at least for healthy young or active older people.

When older guys drink a protein shake with 40 grams of casein right before bed, about half of that protein shows up in their blood overnight — meaning their bodies are good at digesting and using it while they sleep.

If you're a young adult who's overweight or obese, having a casein protein shake before bed doesn't seem to change your metabolism or fat burning in any clear way — it doesn't help or hurt much, based on the studies so far.

If healthy guys drink a protein shake with 20-40 grams of casein right before bed, their bodies keep building muscle overnight — even if they worked out earlier in the day.

If young, healthy guys drink a protein shake with 30 grams of casein before bed after working out, their muscles may recover better overnight because their bodies are building more protein while they sleep.

If young guys drink a protein shake with 30 grams of casein before bed after working out, their bodies keep building muscle overnight better than if they don’t.