Table 1.

Basic characteristics of selected studies.

First Author (Year), Country	Design, Number of Participants Per Group, Age	Exercise Intervention	Ketogenic Diet	Outcomes
Gregory (2017), USA	RCT: exercise + ketogenic diet (n = 12) vs. control (n = 15), 34.58 ± 9.26 years old	6 weeks, 4 CrossFit workouts/week	6 weeks, restricting carbohydrate intake to no more than 50 g/week (<10% of energy), given a detailed guide on acceptable low-carbohydrate, fat, protein rich foods, keeping dietary food intake records, urinary ketone: ketosis > 15 mg/dl	Body composition (weight, body mass index (BMI), body fat, fat mass, lean body mass), performance (vertical jump, standing long jump, total performance time)
Gyorkos (2019), USA	RCT: exercise + carbohydrate-restricted Paleolithic-base diet (n = 12), vs. control (n = 12), 40.9 ± 20.2 years old)	4 weeks, high intensity interval training 10 × 60 s cycling intervals and 60 s of recovery, 3 days/week	4 weeks, carbohydrate-restricted Paleolithic based diet, protein (25%), fat (60%), carbohydrate (15%, 50 g/d), no restricted calories, blood ketone ß-hydroxybutyrate ketone level: 0.53 ± 0.29 mmol/L	Dietary intake (energy, protein, carbohydrate, total, fat, saturated fat, monounsaturated fat, polyunsaturated fat, alcohol, cholesterol), brain derived neurotrophic factor (BDNF), cognitive symptoms and function, cognitive speed and flexibility, cognitive flexibility
Sun (2019), China	RCT: high intensity interval training + low carbohydrate (HIIT, n = 18, 20.8 ± 2.7 years old), moderate intensity continuous training + low carbohydrate (MICT, n = 13, 21.5 ± 3.1 years old), control + low carbohydrate (LC-CON, n = 15, 20.9 ± 3.7 years old), vs. control (n = 15, 21.6 ± 3.9 years old)	4 weeks, high intensity interval training (10 × 6 s cycling sprints and 9 s recovery, total 2.5 min/session), moderate intensity continuous training (30 min cycling, 5 min for warm-up, 50% of VO2peak for 10 min, 60% of VO2peask for 10 min, 5 min for recovery), 5 days/week, pedometers, logbook	4 weeks, carbohydrate (10%, ~50 g/d), fat (65%), protein (~25%), urinary ketone was detected: 97.6 ± 4.5% in LC-CON, 96.2 ± 8.3% in HIIT, and 96.9 ± 6.0% in the MICT, 3-day food records	Weight, BMI, waist circumference, waist-to-hip ratio, VO2peak, fasting glucose, total cholesterol, HDL, LDL, triglycerides,
Perissiou (2020), United Kingdom	RCT: exercise + low carbohydrate (n = 33), vs. control (exercise + standard diet, n = 31), 35.3 ± 9 years old	8 weeks, a combination of aerobic and resistance exercise, 60%~70% heart rate (HR) peak and 85%~95% HRpeak, supervised (1st~2nd week) and unsupervised (3rd~8th week)	8 weeks, carbohydrate (>50 g/d), ß-hydroxybutyrate ketone level: >0.3 mmol/L	Cardiorespiratory fitness (VO2peak), Total cholesterol, HDL, LDL, triglycerides, fasting glucose, CRP, adiponectin, blood pressure, body weight, total body fat, visceral adipose tissue, lean muscle, mass, fat mass index, total bone mineral density
Freedland (2019), USA	RCT: exercise + low carbohydrate diet (n = 11), vs. control (n = 18), average 66 years old	24 weeks, ≥30 min/da, ≥5 days/week	6 months, low carbohydrate (≤20 g/day) until urinary ketone bodies detected	Carbohydrates, fat, protein, calories, weight, BMI, HOMA, glucose, insulin, HbA1c, cholesterol, LDL, HDL, non-HDL, triglycerides, prostate-specific antigen, HsCRP
LaFountain (2019), USA	Prospective intervention study: exercise + ketogenic diet (n = 17), 27.4 ± 6.8 years old vs. exercise + mixed diet (n = 17), 24.6 ± 9.0 years old	12 weeks, progressive resistance training (2 days/week, ~60 min/session, 3 sets of 12 reps at 60%-1 repetition maximum (RM) to 4 sets of 4 reps at 95%-1RM), and cardiopulmonary fitness (running, body-weight circuit training, 30 min)	Limited carbohydrate (25 g/d) and protein (90 g/d), sodium (4~5 g/d), alcohol (≥2 drinks/day), a ketone monitor: ß-hydroxybutyrate ketone level: 1.2 ± 0.3 mM	Basal metabolic rate (RMR), relative RMR, respiratory exchange ratio, % carbohydrate, % fat, anaerobic performance (1RM strength, counter movement, 10 s sprint intervals), resting metabolic rate
Jabekk (2010), Norway	RCT: exercise + ketogenic diet (n = 8), vs. exercise + regular diet (n = 8), between 20~40 years	10 weeks, resistance exercise (12 RM, supine leg press, seated leg extension, seated leg curl, seated chest press, seated rowing, seated shoulder press, seated up down, standing biceps curl)	10 weeks, restricted carbohydrates intake until urinary ketone bodies detected, urine reagent strips	Body weight, lean body mass, fasting blood lipids, glucose, dietary nutrition