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Updated: Aug 7, 2026

A Model of Chronic Nutrient Infusion in the Rat
Published on: August 14, 2013
Intravenous carbohydrate over-feeding: a method for rapid nutritional repletion
1Dunn Clinical Nutrition Unit, 100 Tennis Court Road, Cambridge CB2 1QL, UK.
This study shows that increasing energy intake in cachectic patients with Crohn's disease significantly boosts resting energy expenditure (REE) and promotes lean body mass gain. This enhanced metabolism is linked to increased diet-induced thermogenesis and net lipid synthesis.
Area of Science:
- Metabolic Medicine
- Clinical Nutrition
- Gastroenterology
Background:
- Cachexia in Crohn's disease leads to significant metabolic disturbances.
- Nutritional repletion is crucial for managing disease complications.
- Understanding energy expenditure during repletion is key for effective treatment.
Purpose of the Study:
- To investigate the impact of escalating energy intake on resting energy expenditure (REE) and substrate utilization in a cachectic patient with Crohn's disease.
- To assess changes in body composition and nitrogen balance during nutritional repletion.
- To explore the relationship between energy intake, REE, and diet-induced thermogenesis.
Main Methods:
- Conducted 44 measurements of REE and respiratory quotient (RQ) over 62 days.
- Administered intravenous nutrition, gradually increasing energy intake (EI) from 10 to 21 MJ/day.
- Monitored body composition and nitrogen excretion throughout the study.
Main Results:
- Resting energy expenditure (REE) increased from 4.2 to 6.8 kJ/min with rising EI.
- Body weight increased from 53 to 76 kg.
- Respiratory quotient (RQ) rose above 1.0, indicating net lipid synthesis from carbohydrates, even after feeding cessation.
Conclusions:
- Increased REE during nutritional repletion is driven by lean body mass accretion and diet-induced thermogenesis.
- A significant portion of infused energy was not dissipated, suggesting efficient energy storage.
- Carbohydrate metabolism shifted towards net lipid synthesis, impacting overall energy balance.
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