The Effects of Lowering Dietary Carbohydrates on Health, Exercise Performance and Wellbeing-related Outcomes
Trial Snapshot
- Phase
- Not Applicable
- Status
- Completed
- Sponsor
- University of Ostrava
- Enrollment
- 100
- Locations
- 1
- Primary Endpoint
- Change in the time to exhaustion
Study Overview
Brief Summary
The aim of the study is to investigate the long-term effects of the ketogenic diet and exercise (including interactions) on health markers, exercise performance and wellbeing outcomes in sedentary overweight individuals.
Detailed Description
Intentional nutritional ketosis induced by the low carbohydrate diet is an intensively discussed topic of many scientific as well as non-scientific discussions throughout the areas of healthy living, the sports sciences and often used now for the prevention and treatment of chronic diseases. It has been demonstrated that long-term low-carbohydrate diet is more effective for weight loss and cardiovascular and metabolic risk factor reduction than a low-fat diet. In light of conflicting theories of best practice surrounding a polarized topic that impacts human health and daily work performance, the primary aim of this research project is to examine how low-carbohydrate ketogenic diets affect health markers, exercise performance and wellbeing outcomes in sedentary overweight individuals. Each study subject will be randomized into one of the four arms of the study and will undergo a 12-week intervention, with the exception of the study subjects in the control group, who will undergo no intervention for the period of 12 weeks.
The project outcomes are of immense importance for the investigator's global human health, focus on a unique holistic perspective and have the potential to contribute towards much-needed adjustments in public health recommendations.
Study Design
- Study Type
- Interventional
- Allocation
- Randomized
- Intervention Model
- Parallel
- Primary Purpose
- Prevention
- Masking
- None
Masking Description
No masking will be used in this study.
Eligibility Criteria
- Ages
- 18 Years to 60 Years (Adult)
- Sex
- All
- Accepts Healthy Volunteers
- No
Inclusion Criteria
- •BMI 25.00 - 40.00 kg/m2
- •non-smokers
- •non-excessive alcohol intake (self-reported, ≥ to 2 drinks/day for men or ≥1 drink/day for women)
- •willing to accept random assignment
- •low active individuals over the last 1 year, i.e. no specific sports training or regular exercise (up to once a week) and self-reported physical activity < 150 min/week (IPAQ)
- •no evidence of liver, renal, metabolic, and cardiopulmonary disease and dis-eases contraindicating physical activity, no cancer, no psychiatric illness
- •Physical Activity Readiness Questionnaire (PAR-Q) pass
- •body weight stable for the last 2 months and not actively on a weight loss plan
- •prediabetes state allowed (impaired fasting glucose level, i.e. 5.6 - 6.9 mmol/l; HbA1c 5.7 - 6.4 %)
Exclusion Criteria
- •pregnancy, lactation
- •any specific diet (e.g. vegetarian)
- •use of hypoglycemic, lipid-lowering, antihypertensive, psychiatric medications or medications known to affect body weight or energy expenditure; any medication not noted allowed if the individual had been stable while taking such medication for at least 3 months prior to baseline data collection
Arms & Interventions
Ketogenic diet
Ketogenic diet:
- < 50 g carbohydrates - CHO/d (based on the 1-week pre-intervention habitual diet monitoring)
- protein restriction ≤ 1.5 g/kg free-fat mass (FFM)/day.
- fat type intake recommendation:
- natural fats
- trans-FA reduction
Intervention: Ketogenic diet (Behavioral)
Exercise HIIT (High-Intensity Interval Training)
Exercise intervention:
- HIIT: 5 min warm-up - slow walking, 3 min interval of high-intensity walking (above VT2), 3 min interval of low-intensity walking (40 % VO2peak); 5 min cool-down - slow walking:
Cycle 1
- week 1-3 - 3 sessions/week, total time 31 min/session (4 intervals)
- week 4 - regeneration: only 2 sessions with 2 intervals, keep total time 31 min/session, (+ GXT)
Cycle 2
- week 5-7 - 3 sessions/week, total time 43 min/session (6 intervals)
- week 8 - regeneration: only 2 sessions with 4 intervals, total time 31 min/session, (+ GXT)
Cycle 3
- week 9-11 - 3 sessions/week, total time 55 min/session (8 intervals)
- week 12 - regeneration: only 2 sessions with 6 intervals, total time 43min/session, (+GXT)
Intervention: Exercise HIIT (Behavioral)
Ketogenic diet + Exercise HIIT
Ketogenic diet:
- < 50 g carbohydrates - CHO/d (based on the 1-week pre-intervention habitual diet monitoring)
- protein restriction ≤ 1.5 g/kg free-fat mass (FFM)/day.
- fat type intake recommendation:
- natural fats
- trans-FA reduction
Exercise intervention:
- HIIT: 5 min warm-up - slow walking, 3 min interval of high-intensity walking (above VT2), 3 min interval of low-intensity walking (40 % VO2peak); 5 min cool-down - slow walking:
Cycle 1
- week 1-3 - 3 sessions/week, total time 31 min/session (4 intervals)
- week 4 - regeneration: only 2 sessions with 2 intervals, keep total time 31 min/session, (+ GXT)
Cycle 2
- week 5-7 - 3 sessions/week, total time 43 min/session (6 intervals)
- week 8 - regeneration: only 2 sessions with 4 intervals, total time 31 min/session, (+ GXT)
Cycle 3
- week 9-11 - 3 sessions/week, total time 55 min/session (8 intervals)
- week 12 - regeneration: only 2 sessions with 6 intervals, total time 43min/session, (+GXT)
Intervention: Ketogenic diet (Behavioral)
Ketogenic diet + Exercise HIIT
Ketogenic diet:
- < 50 g carbohydrates - CHO/d (based on the 1-week pre-intervention habitual diet monitoring)
- protein restriction ≤ 1.5 g/kg free-fat mass (FFM)/day.
- fat type intake recommendation:
- natural fats
- trans-FA reduction
Exercise intervention:
- HIIT: 5 min warm-up - slow walking, 3 min interval of high-intensity walking (above VT2), 3 min interval of low-intensity walking (40 % VO2peak); 5 min cool-down - slow walking:
Cycle 1
- week 1-3 - 3 sessions/week, total time 31 min/session (4 intervals)
- week 4 - regeneration: only 2 sessions with 2 intervals, keep total time 31 min/session, (+ GXT)
Cycle 2
- week 5-7 - 3 sessions/week, total time 43 min/session (6 intervals)
- week 8 - regeneration: only 2 sessions with 4 intervals, total time 31 min/session, (+ GXT)
Cycle 3
- week 9-11 - 3 sessions/week, total time 55 min/session (8 intervals)
- week 12 - regeneration: only 2 sessions with 6 intervals, total time 43min/session, (+GXT)
Intervention: Exercise HIIT (Behavioral)
Control Group
The study subjects in this arm will undergo no dietary changes and no exercise intervention.
Outcomes
Primary Outcomes
Change in the time to exhaustion
Time Frame: 12 weeks (baseline + every four weeks)
All study subjects will undergo the Graded Exercise Test, with measuring of the time to exhaustion in minutes.
Change in cardiorespiratory variables - oxygen consumption
Time Frame: 12 weeks (baseline + every four weeks)
All study subjects will undergo the Graded Exercise Test, with measuring of the oxygen consumption (L/min).
Change in cardiorespiratory variables - heart rate
Time Frame: 12 weeks (baseline + every four weeks)
All study subjects will undergo the Graded Exercise Test, with measuring of the heart rate (beats per minute).
Secondary Outcomes
- Biochemical analysis - venous blood(12 weeks (2 times/week))
- Biochemical analysis - capillary blood(12 weeks (2 times/week))
- Anthropometrics - body weight(12 weeks (baseline + every four weeks))
- Anthropometrics - DXA(12 weeks (baseline + outcome))
- InBody (bioimpedance)(12 weeks (baseline + every four weeks))
- Anthropometrics - body height(12 weeks (baseline + every four weeks))
- Anthropometrics - waist circumference(12 weeks (baseline + every four weeks))