Mapping Metabolic Organ Plasticity in Energy Adaptation
Mapping Metabolic Organ Plasticity in Energy Adaptation
Brief Summary (Plain Language)
Many people who lose weight experience a slowdown in their metabolism that is greater than expected. This response, called metabolic adaptation, makes it harder to continue losing weight or to keep weight off over time. The biological reasons for this slowdown are not fully understood.
Some organs in the body, especially the liver and kidneys, use a large amount of energy even when the body is at rest. Although these organs make up only a small portion of body weight, they account for a large share of daily energy use. Changes in the size or function of these organs may play an important role in metabolic adaptation, but this has not been well studied in humans.
The purpose of this study is to understand how different lifestyle approaches affect metabolic adaptation and the size of key metabolic organs. Specifically, the study compares three common strategies:
Adults with overweight will take part in one of these approaches for 10 weeks. Before and after the study period, participants will undergo advanced measurements, including magnetic resonance imaging (MRI) scans to measure liver and kidney size, tests to measure resting metabolism, and assessments of body composition. Some participants will also undergo additional testing to measure daily energy use.
By understanding how different lifestyle strategies influence metabolism and organ size, this study aims to improve knowledge about why weight loss is difficult to maintain and to support the development of more personalized approaches to long-term weight management.
Metabolic adaptation refers to a reduction in resting energy expenditure that is greater than what would be predicted from changes in body weight or body composition. This phenomenon is commonly observed during weight loss and is believed to contribute to weight regain. While metabolic adaptation is well documented, the underlying physiological mechanisms remain unclear.
Highly metabolic organs, including the liver and kidneys, consume a disproportionate amount of energy at rest. Emerging evidence suggests that reductions in the size of these organs during energy deficit states may contribute to declines in resting metabolic rate. However, few human studies have directly examined how different lifestyle interventions influence organ size and how these changes relate to metabolic adaptation.
This study is a 10-week, open-label, lifestyle intervention trial conducted in sedentary adults with overweight. Participants are assigned to one of three intervention groups: resistance training with a normal diet, calorie restriction, or time-restricted eating. All participants are supervised by qualified health professionals throughout the study.
Measurements are conducted before and after the intervention period and include gold-standard assessments of resting metabolic rate, body composition, liver and kidney volume using MRI, and hepatic fat content. A subset of participants undergoes doubly labeled water testing to assess total daily energy expenditure.
The primary goal of the study is to compare the degree of metabolic adaptation across the three lifestyle strategies. Secondary objectives include evaluating changes in liver and kidney volume and determining how these organ-level changes contribute to changes in metabolism. The study is designed to provide mechanistic insight into how exercise- and diet-based interventions influence energy regulation at the organ level.
The results of this research are expected to advance understanding of metabolic adaptation in humans and may help inform more effective and individualized strategies for weight loss and long-term weight maintenance.
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