Weight Loss Composition and Metabolic Adaptation During Hypocaloric Dieting
For patients and families
In plain language
An automatic summary of structured registry data. It is an orientation aid, not a substitute for the official protocol or a physician assessment.
- What is being studied
- The protocol lists: Hypocaloric Diet.
- Who it may be relevant to
- Registry conditions: Obesity. Basic parameters: from 18 years · All.
- What needs checking
- Age, condition and sex are only basic indicators. Prior treatment, laboratory values and other mandatory requirements appear in the eligibility criteria below.
- Where it takes place
- Center list to be confirmed — check the primary protocol.
- Next step
- Save the trial, show it to the treating physician, and confirm current recruitment with the study center. Costs, documents and travel →
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Official title
The Relationship Between Weight Loss Composition, Body Composition Changes, and Metabolic Adaptation During a Hypocaloric Dietary Intervention
Overview
Weight loss induced by hypocaloric dietary interventions is commonly accompanied by reductions in resting metabolic rate (RMR), a phenomenon often described as metabolic adaptation. The magnitude of this decline varies substantially between individuals and may depend not only on the amount of weight lost but also on the composition of weight loss, particularly the relative contributions of fat mass and fat-free mass. This prospective interventional study will investigate whether changes in body composition during a hypocaloric dietary intervention are associated with changes in RMR and metabolic adaptation. Approximately 150 adults with overweight or obesity will participate in a structured dietary program designed to induce moderate energy restriction. Body composition and resting metabolic rate will be assessed before and after the intervention to evaluate associations between fat mass loss, fat-free mass loss, and metabolic responses to weight reduction.
Detailed description
Weight loss achieved through caloric restriction is consistently associated with reductions in resting metabolic rate (RMR). In many individuals, the decrease in energy expenditure exceeds what would be predicted from the loss of body mass or body composition alone, a phenomenon commonly described as metabolic adaptation or adaptive thermogenesis. This response has been proposed as one potential contributor to the difficulty many individuals experience in maintaining weight loss over time.
Fat-free mass is the primary determinant of resting energy expenditure because it includes metabolically active tissues such as skeletal muscle and organs. Consequently, the relative proportion of fat mass and fat-free mass lost during weight reduction may influence the magnitude of RMR decline. Dietary strategies that promote preservation of fat-free mass, such as adequate protein intake and engagement in physical activity, may attenuate metabolic slowing during weight loss. However, substantial inter-individual variability in metabolic responses to weight loss has been reported, and the role of weight-loss composition in shaping these responses remains incompletely understood.
The present study aims to examine the relationship between changes in body composition and changes in resting metabolic rate during a structured hypocaloric dietary intervention in adults with overweight or obesity. Participants will follow individualized dietary plans designed to produce a moderate energy deficit. Body composition will be assessed using dual-energy X-ray absorptiometry (DXA), and resting metabolic rate will be measured using indirect calorimetry at baseline and following completion of the intervention. Anthropometric measures and physical activity patterns will also be recorded.
By evaluating the relative contributions of fat mass loss and fat-free mass loss to changes in energy expenditure, this study aims to improve understanding of the physiological responses to weight reduction. The findings may help inform weight-loss strategies designed to minimize unfavorable metabolic adaptations and support more sustainable long-term weight management.
Interventions
- Behavioral Hypocaloric Diet
Participants will follow individualized dietary plans designed to produce an energy deficit of approximately 500-600 kcal/day relative to measured resting metabolic rate. Protein intake will be prescribed at approximately 1.5 g/kg body weight per day to support preservation of fat-free mass. Dietary plans will be adjusted as needed during the intervention period, and participants will attend regular follow-up visits to monitor progress and adherence.
Primary outcome measures
- Change in Resting Metabolic Rate [Time frame: Baseline to end of dietary intervention (up to 12 months)]
Secondary outcome measures (6)
- Change in Fat Mass [Time frame: Baseline to end of dietary intervention (up to 12 months)]
- Change in Fat-Free Mass [Time frame: Baseline to end of dietary intervention (up to 12 months)]
- Change in Body Weight [Time frame: Baseline to end of dietary intervention (up to 12 months)]
- Change in Abdominal Circumference [Time frame: Baseline to end of dietary intervention (up to 12 months)]
- Intervention Duration [Time frame: Baseline to end of intervention (up to 12 months)]
- Physical Activity Modality [Time frame: Baseline to end of dietary intervention (up to 12 months)]
Eligibility criteria
Inclusion criteria
- Adults aged 18 years and older.
- Individuals living with overweight or obesity.
- Willingness and ability to comply with dietary recommendations and study procedures.
- Provision of written informed consent.
Exclusion criteria
- Diagnosed metabolic or endocrine disorders known to affect energy expenditure.
- Use of medications known to substantially affect metabolism or body composition.
- Pregnancy or breastfeeding.
- Any medical condition that, in the opinion of the investigators, precludes safe participation.
Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.
Healthy volunteers: Yes
Study design
- Allocation
- N/A
- Model
- Single group
- Masking
- Open label
- Primary purpose
- Treatment
Study locations
Center list to be confirmed — check the primary protocol.
Identifiers
NCT: NCT07627256 · 0012134-2