The Study
Casein Protein Supplementation in Trained Men and Women: Morning versus Evening
This study watched two groups of fit people who took a protein shake either in the morning or at night. It found no difference in muscle, fat, or strength after 8 weeks. That means, for people like these, when they took the protein didn’t seem to matter — but it doesn’t prove that timing never matters for anyone.
Analysis score
Maximum 90 for a randomized controlled trial.
Where the score came from
This study asked if drinking a protein shake in the morning or at bedtime helps build more muscle or lose fat in people who already work out a lot.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 540 / 100
Quality score
Participants are randomly assigned to treatment or control groups, minimizing bias. The gold standard for testing whether an intervention causes an effect.
Key takeaways
Summary
Based on the study abstract and findings.
- 1Even though they ate more protein—about 2.4 grams per kilogram of body weight—people didn’t gain fat or muscle.
- 2This means extra protein didn’t hurt or help much if they didn’t change their workouts.
- 326 people drank 54 grams of casein protein every day for 8 weeks—some in the morning, some at night.
- 4Everyone stayed on their normal workout routine.
- 5Their muscle, fat, and strength didn’t change no matter when they drank the shake.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
International Journal of Exercise Science
Year
2017
Authors
J. Antonio, Anya Ellerbroek, C. Peacock, T. Silver
Related Content
Claims (5)
If you're getting the same amount of protein every day, it doesn't matter whether you drink a shake before bed or at another time — you'll gain the same amount of muscle and strength.
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.
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.
If you're already working out, taking 54 grams of casein protein every day for 8 weeks—whether in the morning or at night—won’t noticeably change your strength or how long you can keep lifting weights, as long as your workouts stay the same.
If you're already fit and eat a decent amount of protein, boosting your intake even higher with supplements won’t change your muscle, fat, or performance—as long as your workout routine stays the same.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.