response to caloric restriction

Definition

Target type: biologicalprocess

A change in state or activity of a cell or an organism (in terms of movement, secretion, enzyme production, gene expression, etc.) as a result of a caloric restriction, insufficient food energy intake. [GOC:dph, PMID:15520862]

Caloric restriction (CR) is a dietary intervention that involves reducing calorie intake without causing malnutrition. It triggers a complex cascade of biological processes that have been linked to increased lifespan, reduced risk of age-related diseases, and improved metabolic health. The response to CR is multifaceted and involves changes at the cellular, tissue, and systemic levels. Here's a detailed breakdown:

1. **Cellular Level:**
* **Reduced Insulin/IGF-1 Signaling (IIS):** CR decreases insulin and insulin-like growth factor 1 (IGF-1) signaling pathways. This downregulation activates the transcription factor FOXO, leading to enhanced stress resistance, cellular repair mechanisms, and increased lifespan.
* **Enhanced Autophagy:** CR promotes autophagy, a cellular process that degrades and recycles damaged components, contributing to cellular renewal and improved function.
* **Mitochondrial Biogenesis:** CR stimulates the production of new mitochondria, improving energy production and reducing oxidative stress.
* **Sirtuin Activation:** CR activates sirtuins, a family of NAD+-dependent deacetylases, which play crucial roles in regulating metabolism, stress response, and lifespan.

2. **Tissue Level:**
* **Improved Brain Function:** CR has been shown to enhance cognitive function, improve memory, and protect against neurodegeneration. It may do this by increasing neurotrophic factors like BDNF, promoting neuronal plasticity, and reducing inflammation in the brain.
* **Enhanced Cardiovascular Health:** CR can improve cardiovascular health by lowering blood pressure, reducing blood lipid levels, and improving heart function.
* **Improved Liver Function:** CR can protect the liver from damage, reduce inflammation, and improve metabolic function.
* **Muscle Maintenance:** While CR can lead to some muscle mass loss, it promotes a shift towards slower-twitch, fatigue-resistant muscle fibers, enhancing endurance and metabolic efficiency.

3. **Systemic Level:**
* **Metabolic Adaptations:** CR promotes metabolic adaptations that increase insulin sensitivity, reduce inflammation, and enhance glucose homeostasis.
* **Hormonal Changes:** CR alters hormone levels, leading to a decrease in growth hormone, thyroid hormone, and sex hormones, while increasing adiponectin and leptin.
* **Immune System Modulation:** CR modulates the immune system, promoting an anti-inflammatory state and reducing the risk of age-related chronic diseases.

4. **Molecular Mechanisms:**
* **Epigenetic Modifications:** CR induces epigenetic modifications, such as changes in DNA methylation and histone acetylation, influencing gene expression and contributing to the beneficial effects of CR.
* **Microbiome Alterations:** CR can alter the composition and function of the gut microbiome, influencing metabolic processes and immune function.

5. **Individual Variability:**
* **Age and Sex:** The response to CR can vary depending on age and sex. Younger individuals may experience more pronounced benefits than older individuals.
* **Genetic Background:** Genetic differences can influence the effectiveness of CR, with some individuals experiencing greater benefits than others.
* **Lifestyle Factors:** Lifestyle factors, such as exercise and sleep, can interact with the effects of CR.

CR is a complex biological phenomenon with numerous benefits. Understanding the intricate mechanisms involved in the response to CR is essential for optimizing its potential for promoting health and longevity. However, it's crucial to consult with a healthcare professional before implementing any dietary restrictions.'
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