Time-Restricted Eating and Muscle Hypertrophy

The Influence of 16:8 Time-Restricted Eating on Resistance Exercise-Induced Skeletal Muscle Hypertrophy

The purpose is to examine the effects of time-restricted eating (TRE; consuming all calories within an 8-hour period each day) vs. normal eating (CON; consuming same kcals and protein as TRE, but during a 10-13 hr eating window each day) during 8 weeks of resistance exercise on body composition and muscle mass (whole muscle and single fiber), muscular performance, anabolic protein signaling, single muscle fiber characteristics, and the gut microbiome in well-trained young men and women.

Study Overview

• Status: Completed
• Conditions: Muscle Hypertrophy; Healthy and Well-Trained Men and Women
• Intervention / Treatment: Other: Time Restricted Eating; Other: Resistance Training; Dietary supplement: Whey Protein; Other: Normal Feeding

Detailed Description

The primary goal pertains to muscle hypertrophy (not fat loss), thus all participants will be placed in a 10% caloric surplus.

• Study Type: Interventional
• Enrollment (Actual): 20
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United States
  • California
    • Fullerton, California, United States, 92831
      • Center for Sport Performance at California State University, Fullerton

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 35 years (ADULT)
• Accepts Healthy Volunteers: Yes
• Genders Eligible for Study: All

Description

Inclusion Criteria:

• 18-35 years old with <25% (men) or <30% (women) body fat
• have experience in resistance exercise for the whole body and performed resistance exercise at least 3 times per week the last 12 months
• be able to perform all necessary exercises with safe technique and no pain
• be able to squat 1.5x (men) or 1x (women) body weight
• be able to bench press 1.1x (men) or 0.55x (women) body weight
• be on a non-specialized, mixed macronutrient diet
• have a lifestyle which enables a reasonably consistent 7+ hours of sleep per night
• be free of any current joint, musculoskeletal, and/or neuromuscular injuries

Exclusion Criteria:

• have any known current illness, prohibitive muscular or neuromuscular problem, hypertension, cardiac, pulmonary, liver, kidney, insulin or any other metabolic disorders (e.g. Type I or Type II diabetes)
• are lactose intolerant or unable to consume whey protein for any reason
• are on any medications known to affect protein metabolism
• have taken antibiotics in the last 6 months
• cannot refrain from consuming any alcoholic beverages, nicotine, or marijuana (or derivative) for a period of 48 hours prior to data collection (pre and post testing)
• consume alcohol >2x per week
• consume any analgesic or anti-inflammatory drug(s), prescription or non-prescription, chronically or within 48 hours of data collection
• consume any recreational drug(s), prescription or non-prescription, legal or illegal, chronically or within 30 days of data collection
• consume any caffeine or food within 12 hours of data collection
• cannot refrain from physical exercise (outside of activities of daily living) outside of what is prescribed by the research team for the duration of the study
• cannot refrain from using recovery methods such as electric stimulation, hot/cold therapy, massage, chiropractic, or personal air/water devices (Normatech, etc.)
• have utilized any anabolic steroid, currently or in the past
• cannot refrain from consumption of any supplementation (creatine, multivitamin, fish oil, protein powder, BCAA, pre-workouts, etc.) outside of what is provided
• cannot refrain from consuming any supplemental pro or prebiotics or other items that intentionally alter the gut microbiome
• fail to adhere to the nutritional guidelines or miss >3 of the exercise sessions
• were recently pregnant, trying to become pregnant, or are currently breastfeeding

Study Plan

How is the study designed?

Design Details

• Primary Purpose: OTHER
• Allocation: RANDOMIZED
• Interventional Model: PARALLEL
• Masking: DOUBLE

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
EXPERIMENTAL: Time Restricted Eating (16:8); Participants will consume all calories within an 8 hour window each day.	Other: Time Restricted Eating; Diet will be tracked and reported every day to a qualified dietitian.; Other: Resistance Training; 8 weeks of supervised and programmed whole body resistance training, performed 4x per week; Dietary supplement: Whey Protein; Consumed on all exercise days.
ACTIVE_COMPARATOR: Control; Participants will consume all calories within a ~12 hour window each day (4 separate meals + needed snacks).	Other: Resistance Training; 8 weeks of supervised and programmed whole body resistance training, performed 4x per week; Dietary supplement: Whey Protein; Consumed on all exercise days.; Other: Normal Feeding; Diet will be tracked and reported every day to a qualified dietitian.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Changes in Muscle Size - Lower Body	via Ultrasound	Pre, Mid (4 weeks), and Post (8 weeks)
Changes in Muscle Size - Upper Body	via Ultrasound	Pre, Mid (4 weeks), and Post (8 weeks)
Changes in Fiber Type-Specific Size	Single muscle fiber analysis	Pre and Post (week 8)
Changes in Body composition	via BodPod	Pre, Mid (4 weeks), and Post (8 weeks)
Acute Exercise Induced Fiber Type-Specific Anabolic Signaling (Total Concentration and Phosphorylation Status)	Men only; assessed via single fiber Simple Western	Day 1 of exercise training

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Changes in Maximal Strength	1RM on bench press, squat, and leg extension	Pre and Post (week 8)
Changes in Maximal Muscular Endurance	Maximal repetitions on bench press and leg press	Pre and Post (week 8)
Changes in Gut Microbiome	via stool sample	Pre, Mid (week 2, 4, 6), and Post (week 8)
Changes in Fiber Type Composition	Single Fiber via SDS-PAGE	Pre and Post (week 8)
Changes in Fiber Type-Specific Resting Anabolic Signaling (Total Concentration and Phosphorylation Status)	via single fiber Simple Western	Pre and Post (week 8)
Changes in Mood	via Questionnaire	Weekly for duration of the intervention (8 weeks)
Changes in Enjoyment of Diet	via Questionnaire	Weekly for duration of the intervention (8 weeks)
Changes in Sleep (total and quality)	via Questionnaire	Weekly for duration of the intervention (8 weeks)
Changes in Menstrual Cycle	via Questionnaire; women only	Pre, Mid (week 4), and post (week 8)
Total Training Volume		After 8 weeks
Nutrient Intake	Total Kcal and grams of protein, fat, and carbohydrates	Daily, starting 7 days before the study and continuing for 8 additional weeks

Collaborators and Investigators

• Sponsor: California State University, Fullerton
• Collaborators: San Francisco State University

Study record dates

Study Major Dates

• Study Start (ACTUAL): June 24, 2019
• Primary Completion (ACTUAL): July 15, 2021
• Study Completion (ACTUAL): February 5, 2023

Study Registration Dates

• First Submitted: June 25, 2019
• First Submitted That Met QC Criteria: June 26, 2019
• First Posted (ACTUAL): June 27, 2019

Study Record Updates

• Last Update Posted (ESTIMATE): February 9, 2023
• Last Update Submitted That Met QC Criteria: February 8, 2023
• Last Verified: February 1, 2023

More Information

Terms related to this study

• Keywords: Hypertrophy; Time Restricted Eating; Intermittent Fasting; Protein Signaling; Anabolic
• Additional Relevant MeSH Terms: Pathological Conditions, Anatomical; Hypertrophy
• Other Study ID Numbers: CSP Fullerton

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No