REDs
This acronym refers to the core concept behind REDs, defined as dietary energy intake minus exercise energy expenditure, relative to fat-free mass.
What is energy availability (EA)?
The authors argue that REDs symptoms are often non-specific and may result from this accumulated burden of physical and psychological stress.
What is allostatic load?
This hypothesis suggests that high protein intake increases acid load, leading to calcium loss from bones.
What is the acid-ash hypothesis?
Energy availability is defined as dietary energy intake minus this component.
What is exercise energy expenditure?
Each participant exercised daily at 70% of this physiological capacity.
What is VO₂max?
According to the article, this is the primary reason the REDs model is difficult to validate in practice.
What is the inability to accurately measure energy availability in the field?
This aspect of REDs research, often assumed to be robust, is actually based on short-term studies with limited relevance to long-term outcomes.
What is the evidence for LEA’s impact on bone health?
According to the review, this mineral is leached from bone to neutralize dietary acid load in states of metabolic acidosis.
What is calcium?
This is the energy availability level (in kcal/kg LBM/day) at which energy balance is considered “normal” or “balanced” in this study.
What is 45 kcal/kg LBM/day?
The study suggests maintaining energy availability above this threshold is necessary to protect bone health in active young women.
What is 30 kcal/kg LBM/day?
This tool was introduced by the authors to provide a more holistic and unbiased approach to athlete health evaluation.
What is the Athlete Health and Readiness Checklist (AHaRC)?
This conceptual flaw, according to the authors, makes REDs difficult to falsify and thus scientifically problematic.
What is circular reasoning — diagnosing REDs by assuming symptoms are caused by LEA unless proven otherwise?
This hormone, stimulated by protein intake, plays a key role in bone formation and remodeling.
What is insulin-like growth factor 1 (IGF-1)?
This bone resorption marker increased significantly only at the most severe energy restriction (10 kcal/kg LBM/day).
What is NTX (N-telopeptide)?
The study concluded that bone formation is impaired at this moderate level of energy availability, even though bone resorption is not.
What is 30 kcal/kg LBM/day?
The REDs model evolved from this earlier model introduced in 1993 that focused on eating disorders, amenorrhea, and low bone density.
What is the Female Athlete Triad?
This concept, highlighted in Figure 3, suggests symptoms often labeled as REDs may come from multiple stressors including training, sleep, illness, and mental health.
What is multifactorial causation or accumulated allostatic load?
In meta-analyses, high protein intake had this effect on bone mineral density (BMD) at the lumbar spine.
What is a small but positive effect?
These two bone formation markers were suppressed at all levels of energy restriction.
What are osteocalcin (OC) and PICP (procollagen type I carboxy-terminal propeptide)?
The study used this design, in which each participant underwent both balanced and restricted energy conditions.
What is a randomized, repeated-measures design?
Most studies cited in support of REDs are this type of study design, which limits the ability to draw causal conclusions.
What are observational or cross-sectional studies?
According to the paper, this percentage of REDs-related publications are narrative reviews, not original research.
What is approximately 40%?
Protein’s indirect positive effect on bone is largely mediated by improvements in this tissue.
What is muscle (or lean body mass)?
Increased NTX levels were associated with suppression of this reproductive hormone.
What is estradiol?
This anabolic hormone, suppressed by low energy availability, is closely associated with PICP levels.
What is insulin?