Lipolysis and Fat Oxidation Are Not Altered with Presleep Compared with Daytime Casein Protein Intake in Resistance-Trained Women.
Level 2 - randomized trial
Individual randomized crossover trial
PubMed 31504693 · doi:10.1093/jn/nxz186
What was done
Thirteen young, resistance-trained women (mean age 22 ± 1 years, BMI 24.3 ± 0.8 kg/m²) completed a randomized crossover study. Following a full-body resistance exercise session at 65% 1RM, participants consumed either daytime protein (30 g casein 30 minutes post-exercise) and a presleep noncaloric sensory-matched placebo 30 minutes before sleep (PRO-PLA), or the reverse (PLA-PRO), switching order on a subsequent visit. Subcutaneous abdominal adipose tissue (SCAAT) lipolysis, resting metabolism (indirect calorimetry), and plasma biomarkers (glucose, insulin, nonesterified fatty acids, glycerol) were measured at baseline, overnight, and the next morning.
What was found
No significant differences were observed between conditions. Interstitial glycerol concentrations (μM) changed from baseline 669 ± 137 to 321 ± 77.1 the next morning in PRO-PLA, and from baseline 524 ± 109 to 333 ± 68.0 in PLA-PRO. Fat oxidation rates (g/min) were 5.70 ± 0.35 at baseline and 5.00 ± 0.28 the next morning for PRO-PLA, versus 6.59 ± 0.32 at baseline and 5.44 ± 0.27 for PLA-PRO. No differences were detected in any other measured parameters.
Why it matters
This study shows that consuming casein protein before sleep does not suppress overnight subcutaneous fat breakdown or whole-body fat oxidation compared to daytime consumption, supporting presleep protein as a viable timing strategy for active women.
Limits
The study evaluated only acute single-night responses in a small sample of 13 resistance-trained women, precluding conclusions about long-term body composition. The results cannot be generalized to men, untrained individuals, or other protein sources.
Cited by
- supports Research by Mike Ormsbee demonstrates that consuming 40 grams of protein 30 minutes before bed does not impair fat oxidation or increase body fat gain.