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.

Eating a bedtime protein shake with casein doesn’t seem to change how many calories your body burns at rest if you're a healthy older adult — at least according to one small study.

If healthy young adults drink a casein protein shake before bed, they might burn slightly less fat overnight than if they had whey protein—but about the same amount as if they had nothing at all.

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.

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 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.