Table.

Summary of studies on the effects of exercise timing on exercise adherence and weight change

Reference	Participants	Design	Exercise Timing Randomized	Exercise Setting	Key Findings	Measured Potential Moderators/ Mediators
Studies evaluating effects on exercise frequency and weekly minutes
Schumacher et al. (2019)	375 physically active adults in the National Weight Control Registry	Correlational	No	Community	68% of participants had a consistent exercise time, of whom 48% performed exercise in the early morning (4:00–8:59 am). Temporally consistent exercisers (>50% of exercise sessions/wk at a consistent time of day) performed more exercise than temporally inconsistent exercisers (4.8 vs. 4.4 d/wk, p=.007; 350 vs. 285 min/wk, p=.03; 86% vs. 74% achieving ≥150 min/wk; p=.004).	Exercise habit strength, exercise cue consistency
Bond et al. (2017)	33 adults seeking bariatric surgery participating in a 6-wk preoperative exercise intervention	Secondary analysis from RCT non-specific to Exercise timing	No	Community	At post-tx, a greater % of bouted morning exercise (4:00–11:59 am) related to greater pre- to post-tx increases in exercise (p=.03). A greater proportion of morning exercisers (>50% of exercise in the morning) achieving ≥150 min/wk of exercise than non-morning exercisers (p=.04).	N/A
Studies evaluating effects on weight
Chomistek et al. (2016)	7,157 older women in the Women’s Health Study	Correlational	No	Community	Lower % of accelerometer counts in the morning (before 12:00 pm) related to higher odds of obesity; women in the lowest quartile for morning exercise had 26% higher odds of obesity compared to those in the highest quartile (p=.02).	N/A
Willis et al. (2019)	88 inactive young adults with overweight/obesity participating in the Midwest Exercise Trial-2	Secondary analysis from RCT non-specific to exercise timing	No	Supervised exercise training	10-month weight loss was greater among early exercisers (≥50% exercise sessions from 7:00–11:59 am) compared to late exercisers (≥50% exercise sessions from 3:00–7:00 pm) and controls (no supervised exercise; p’s<.001). A greater proportion of early exercisers (vs. late) achieved ≥5% weight loss (p=.007). 10-month weight Δ negatively related to proportion of exercise sessions completed in the early period (p<.001).	Energy intake, energy intake timing, RMR
Alizadeh et al. (2017)	48 inactive women with overweight BMIs in a 6-wk exercise training study on exercise timing	RCT	Yes	Supervised exercise training	Morning exercisers (8:00–10:00 am) had greater 6-wk reductions in weight (p=.04) and BMI (p=.04) compared to afternoon exercisers (2:00–4:00 pm).	Body composition, appetite and eating desire scores, dietary intake
Brooker et al. (2019)	20 inactive adults with overweight/obesity in a 12-wk exercise study assessing the feasibility and acceptability of exercise timing	RCT	Yes	Supervised exercise training + community	The intervention was feasible (e.g., 90% of enrolled participants completed the study; the morning group completed 94% of supervised exercise sessions and the evening group completed 87%) and acceptable (e.g., perceived enjoyment of exercise was similar in the morning [67%] and evening groups [64%]).	Body composition; RMR; energy intake; appetite, food preferences, and eating behaviors; time use; sleep quality; chronotype; exercise enjoyment
Di Blasio et al. (2010)	42 inactive, postmenopausal women with overweight/obesity in a 3-month walking program	Non-randomized trial	No	Supervised exercise training in the community	Δ in body weight did not differ between groups, but the evening group (6:00–8:00 pm) had greater decreases in % fat mass compared to the morning group (7:00–9:00 am; p=.037). Groups also differed in daily kcal distribution (e.g., evening group had greater increases in morning kcal intake and decreases in afternoon intake; p’s<.05).	Body composition, dietary intake

Note. RCT=randomized controlled trial, BMI=body mass index, RMR=resting metabolic rate