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(OR14-02-26) Effect of 0.8 g/kg/d vs 1.6 g/kg/d Protein Intake in a Traditional or Time-Restricted Eating Pattern on Whole-Body Protein Turnover and Myofibrillar Protein Breakdown

Sunday, July 26, 2026
4:42 PM - 4:54 PM ET
Location: Maryland Ballroom C
Disclosure(s):
Joseph J. Matthews, PhD: No relevant financial relationship(s) with ineligible companies to disclose.
David D. Church, PhD: Centers for Medicare & Medicaid Services: Consultant (Ongoing)
Dairy Management, Inc.: Grant/Research Support (Ongoing)
National Cattlemen’s Beef Association: Consultant (Terminated, October 1, 2024); Grant/Research Support (Terminated, October 1, 2024)
National Pork Board: Advisory Committee/Board Member (Ongoing); Grant/Research Support (Ongoing); Independent Contractor (including contracted research) (Ongoing)
Soy Connection: Consultant (Ongoing)
Vitality Blueprint: Consultant (Terminated, December 31, 2024)
Objectives: Time-restricted eating (TRE) is a popular dietary pattern for controlling energy intake and combating obesity, cardiovascular, and metabolic disease. However, a compressed eating window means an extended catabolic period, which may affect whole-body and muscle proteostasis in groups at risk of age-related muscle loss [1]. We aimed to assess 24h protein kinetics at two levels of protein intake: 0.8 (RDA) and 1.6 g/kg/d (2×RDA) within a traditional (TRAD) and a TRE pattern in middle-aged and older adults.

Methods: 48 adults (age: 64 ± 7 y, body mass index: 27 ± 4 kg/m2) were randomized to one of four parallel groups: RDA protein in a TRAD (n=13) or TRE (n=11) pattern, or 2×RDA protein in a TRAD (n=10) or TRE (n=14) pattern. Participants received 3 days of meals with beef as the primary protein source. Meals on days 1-2 were consumed at home; on day 3 participants reported to the laboratory for a 24-h controlled feeding study. Meals were consumed within the following eating windows: TRAD 07:30-18:00h and TRE 12:00-17:30h. Upon arrival, participants ingested 10 mg methyl-d3-3MH (D-3MH), to determine D-3MH decay rate (k) and myofibrillar protein breakdown [2], and 2 g 15N-alanine, to determine whole-body net protein balance (WBNB) [3]. Two-way ANOVAs were conducted to assess between-group differences and interactions. Data are reported as mean ± SD; statistical significance as p< 0.05.

Results: WBNB (TRAD: RDA -0.03±0.31 vs 2×RDA 0.39±0.35 g/kg/d; TRE: RDA -0.15±0.23 vs 2×RDA 0.25±0.24 g/kg/d) was significantly higher in the 2×RDA groups compared with the RDA groups (p < 0.001). There was no significant difference between TRAD and TRE (p=0.129) and no significant interaction between protein intake and eating pattern (p=0.902). No significant differences in isotopic decay of D-3MH were detected for protein amount (p=0.169), eating pattern (p=0.206), or their interaction (p=0.477); decay rate k = RDA TRAD 0.036>±0.008, TRE 0.038±0.012; 2×RDA TRAD 0.028±0.012, TRE 0.036±0.017.

Conclusions: Higher protein intake improved WBNB irrespective of whether consumed in a TRAD or TRE pattern, while myofibrillar protein breakdown was unaffected by protein intake of eating pattern. These findings do not support an adverse effect of TRE on whole-body protein turnover in middle-aged and older adults.

Funding Sources: Funding was provided by the National Cattlemen’s Beef Association (NCBA).