Indices of Metabolic Flexibility and Ketone Production During Short-Term Energy Deficit With and Without Dietary Carbohydrate Restriction
试验速览
- 阶段
- 不适用
- 状态
- 已完成
- 发起方
- 入组人数
- 30
- 试验地点
- 1
- 主要终点
- Carbon dioxide production and breath acetone concentration
研究概览
简要总结
This randomized, interventional study examines the effects of short-term carbohydrate restriction, with and without caloric restriction, on indices of metabolic flexibility in healthy adults. Participants are randomly assigned to either a low-carbohydrate diet or a standard diet under energy balance, followed by the same diet under controlled caloric restriction. Primary outcomes include measures of carbon dioxide production, breath ketones and interstitial glucose. Secondary outcomes include blood and urinary ketones, body weight, body composition, and selected metabolic biomarkers.
详细描述
This is a monocentric, randomized, open-label nutrition intervention conducted in healthy adults aged 18 to 40 years. The study investigates the effects of short-term carbohydrate and caloric restriction on indices of metabolic flexibility.
After screening and baseline assessments, participants undergo an initial period of energy balance with a standardized diet, followed by a 2-week intervention phase. Participants are randomly assigned in a 1:1 ratio to either a low-carbohydrate diet or a standard mixed diet. Participants are instructed to maintain their habitual physical activity throughout the study. During the first week of the intervention period, energy intake is equivalent to estimated energy requirements. During the second week, energy intake is reduced by ~500 kcal/d.
Metabolic outcomes are assessed using repeated laboratory and remote measurements. Primary outcomes include breath-based measures of carbon dioxide and acetone production, as well as continuous glucose monitoring. Secondary outcomes include urinary and capillary blood ketones, body weight, body composition, resting metabolic rate, plasma glucose and selected biomarkers (leptin, insulin, triiodothyronine, GLP-1, HbA1c).
Data are collected at baseline, during the intervention, and post-intervention. The total participation time per participant is approximately three weeks. The study aims to characterize short-term metabolic responses to dietary carbohydrate manipulation and energy deficit under controlled conditions.
研究设计
- 研究类型
- Interventional
- 分配方式
- Randomized
- 干预模型
- Parallel
- 主要目的
- Other
- 盲法
- None
入排标准
- 年龄范围
- 18 Years 至 40 Years（Adult）
- 性别
- All
- 接受健康志愿者
- 是
入选标准
- •Age 18-40 years
- •Body mass index (BMI) 18.5-27 kg/m²
- •Regular exercise or vigorous physical activity at least once per week
- •Willing and able to comply with the dietary intervention and study procedures
- •For female participants: non-pregnant and using hormonal contraception
排除标准
- •Acute or chronic illness
- •Metabolic disorders or conditions associated with altered glucose or lipid metabolism (exclusion of pre-diabetes and diabetes via HbA1c measurement)
- •Use of medications known to interfere with study outcomes
- •Intolerance or allergy to components of the study diets
- •Pregnancy or breastfeeding
研究组 & 干预措施
Low-Carbohydrate Diet
Participants assigned to this arm follow a low-carbohydrate diet. Daily carbohydrate intake is reduced to approximately 75-125 g per day (about 15% of total energy intake), with remaining energy derived primarily from fat (~70%) and protein (~15%). Diets are individually tailored to meet estimated energy and micronutrient requirements. Participants are instructed to maintain their habitual physical activity throughout the study.
干预措施: Low-Carbohydrate Diet (Other)
Standard Diet
Participants assigned to this arm follow a standard mixed diet combined. The diet consists of approximately 50-55% carbohydrates, 25-35% fat, and 15% protein. Diets are individually tailored to meet estimated energy and micronutrient requirements. Participants are instructed to maintain their habitual physical activity throughout the study.
干预措施: Standard Diet With Caloric Restriction (Other)
结局指标
主要结局
Carbon dioxide production and breath acetone concentration
时间窗: Baseline, during the energy-deficit intervention period, and post-intervention (over approximately 3 weeks)
Carbon dioxide production and breath acetone concentration are assessed using portable breath analysis devices during standardized daily measurements and timepoints.
Interstitial glucose concentration assessed by continuous glucose monitoring
时间窗: Continuously assessed throughout the study period (approximately 3 weeks)
Continuous glucose monitoring is used to assess interstitial glucose concentration, including average glucose levels, glucose variability, and time in glycemic ranges.
次要结局
- Urinary ketone concentration(Daily during the study period (approximately 3 weeks))
- Capillary blood ketone concentration(Daily during the study period (approximately 3 weeks))
- Fasting capillary blood glucose concentration(Daily during the study period (approximately 3 weeks))
- Body weight(Daily during the study period (approximately 3 weeks))
- Fat Mass(Baseline (Day 1), mid-intervention (approximately Day 14), and post-intervention (approximately Day 21))
- Fat-Free Mass(Baseline (Day 1), mid-intervention (approximately Day 14), and post-intervention (approximately Day 21))
- Body Fat Percentage(Baseline (Day 1), mid-intervention (approximately Day 14), and post-intervention (approximately Day 21))
- Resting metabolic rate(Baseline (Day 1), mid-intervention (approximately Day 14), and post-intervention (approximately Day 21))
- Plasma Leptin Concentration(Baseline (Day 1), mid-intervention (approximately Day 14), and post-intervention (approximately Day 21))
- Plasma Insulin Concentration(Baseline (Day 1), mid-intervention (approximately Day 14), and post-intervention (approximately Day 21))
- Plasma Triiodothyronine (T3) Concentration(Baseline (Day 1), mid-intervention (approximately Day 14), and post-intervention (approximately Day 21))
- Plasma Glucagon-Like Peptide-1 (GLP-1) Concentration(Baseline (Day 1), mid-intervention (approximately Day 14), and post-intervention (approximately Day 21))
研究者
Karsten Koehler
Prof. Dr. Karsten Köhler
Technical University of Munich