The Effects of Lowering Dietary Carbohydrates on Health, Exercise Performance and Wellbeing-related Outcomes
- Conditions
- Diet ModificationObesity
- Interventions
- Behavioral: Ketogenic dietBehavioral: Exercise HIIT
- Registration Number
- NCT03934476
- Lead Sponsor
- University of Ostrava
- 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.
Recruitment & Eligibility
- Status
- COMPLETED
- Sex
- All
- Target Recruitment
- 100
- 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 %)
- 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
Study & Design
- Study Type
- INTERVENTIONAL
- Study Design
- PARALLEL
- Arm && Interventions
Group Intervention Description Ketogenic diet 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 Exercise HIIT (High-Intensity Interval Training) Exercise HIIT 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) Ketogenic diet + Exercise HIIT 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) Ketogenic diet + Exercise HIIT 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 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)
- Primary Outcome Measures
Name Time Method Change in the time to exhaustion 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 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 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 Outcome Measures
Name Time Method Biochemical analysis - capillary blood 12 weeks (2 times/week) All study subjects will undergo biochemical analysis of capillary blood - βHB and fasting glukose in mmol/L.
Anthropometrics - body weight 12 weeks (baseline + every four weeks) All study subjects will undergo anthropometric assessment of the body weight, measured in kg.
Anthropometrics - DXA 12 weeks (baseline + outcome) All study subjects will undergo anthropometric assessment of DXA - total abdominal fat, measured in kg.
Biochemical analysis - venous blood 12 weeks (2 times/week) All study subjects will undergo biochemical analysis of venous blood - HBA1c in mmol/mol.
InBody (bioimpedance) 12 weeks (baseline + every four weeks) All study subjects will undergo antrhropometric assessment of bioimpedance using the InBody device showing the percentage of water and fat in the organism, measured in % of total body weight.
Anthropometrics - body height 12 weeks (baseline + every four weeks) All study subjects will undergo anthropometric assessment of the body height, measured in cm.
Anthropometrics - waist circumference 12 weeks (baseline + every four weeks) All study subjects will undergo anthropometric assessment of the waist circumference, measured in cm.
Trial Locations
- Locations (1)
University of Ostrava
🇨🇿Ostrava, Moravian-Silesian Region, Czechia