Browse the evidence

Immune system activation (e.g., by microbial challenges) triggers an inflammatory response that increases sleep duration and intensity, serving as a homeostatic regulation of slow-wave sleep.

When you are sick, your body's increased sleep drive is a biological mechanism to help you recover. Listen to this signal and allow yourself to rest, as sleep actively supports your immune defense during infection.

Disease-associated inflammation is a primary etiologic driver of malnutrition, causing anorexia, increased resting energy expenditure, and muscle catabolism, distinct from simple starvation.

In sick patients, malnutrition isn't just about not eating enough; the body's inflammatory response actively breaks down muscle and increases energy needs. Treating the inflammation is as important as providing nutrition.

High dietary fiber intake protects against colitis by increasing short-chain fatty acids (SCFAs) like acetate, which bind to GPR43 and GPR109A receptors on gut epithelial cells to activate the NLRP3 inflammasome and promote gut homeostasis.

To support gut health and reduce inflammation, prioritize a diet high in dietary fiber. This feeds gut bacteria to produce short-chain fatty acids (like acetate), which activate specific receptors (GPR43/GPR109A) on your gut lining. This process triggers a protective immune response (NLRP3 inflammasome) that maintains gut integrity and prevents inflammation.

Visceral fat directly secretes interleukin-6 (IL-6) into the portal circulation, which correlates with systemic inflammation (CRP) and contributes to insulin resistance in obese humans.

For individuals with high abdominal fat, the location of fat matters biologically. Visceral fat actively releases inflammatory markers like IL-6 into the liver, which can drive insulin resistance. Reducing visceral fat through medical or lifestyle interventions may mitigate this inflammatory pathway.

Dietary supplementation with butyrate and propionate protects against diet-induced obesity and improves glucose tolerance in mice, with butyrate and propionate also reducing food intake via FFAR3-independent mechanisms.

In a high-fat diet context, supplementing with butyrate and propionate (specifically at efficacious doses like 2.5-5% for butyrate and 2.2-4.3% for propionate in the diet) can prevent weight gain and improve glucose tolerance in mice. Butyrate also reduces food intake through mechanisms that do not rely on the FFAR3 receptor. These findings suggest that specific SCFA supplementation may be a viable strategy for metabolic health, though human translation requires further study.

Butyrate and propionate acutely stimulate the secretion of gut hormones (GLP-1, GIP, PYY) in mice, with butyrate being the most potent stimulator of anorexigenic peptides.

Acute oral administration of butyrate (400 mg/kg) in fasted mice rapidly increases levels of GLP-1, GIP, PYY, and amylin, with butyrate being the most potent stimulator of anorexigenic peptides. Propionate also stimulates GIP and amylin but not GLP-1 or PYY. Acetate has no significant acute effect on these hormones. This suggests butyrate and propionate may have distinct roles in appetite regulation via gut hormones.

SGLT2 inhibitors lower blood pressure by approximately 4-6 mmHg systolic and 1-2 mmHg diastolic, primarily through plasma volume contraction and reduced arterial stiffness.

SGLT2 inhibitors provide a modest but consistent reduction in blood pressure (4-6 mmHg systolic). This effect is driven by the body excreting more sodium and water, leading to a slight contraction in blood volume and reduced stiffness in arteries.

SGLT2 inhibitors cause an acute, dose-dependent reduction in eGFR (~5 ml/min/1.73m2) and a ~30-40% reduction in albuminuria, which are protective renal hemodynamic effects rather than signs of kidney damage.

When you start an SGLT2 inhibitor, your eGFR (a measure of kidney function) may drop slightly at first. This is a normal, protective response where the kidney reduces its internal filtering pressure to prevent long-term damage. This acute drop is associated with a significant reduction in albuminuria (protein in urine) and long-term kidney protection.

EPA and DHA stabilize atherosclerotic plaques by reducing macrophage infiltration and matrix metalloproteinase (MMP) expression, thereby lowering the risk of plaque rupture.

For patients with existing atherosclerosis, EPA and DHA supplementation may help stabilize plaques by reducing inflammation within the vessel wall. This is achieved by incorporating into the plaque and reducing macrophage presence, potentially lowering the risk of rupture.

Acute elevation of plasma free fatty acids (FFA) induces insulin resistance in human skeletal muscle by inhibiting insulin-stimulated glucose transport activity, rather than glucose phosphorylation.

High levels of free fatty acids in your blood (often from high fat intake or obesity) can block insulin's ability to move glucose into your muscles. This happens because fat interferes with the insulin signaling pathway (PI 3-kinase) before glucose can be used. Managing blood fat levels through diet and exercise can help restore this sensitivity.

Elevated plasma free fatty acids blunt insulin-stimulated IRS-1–associated phosphatidylinositol 3-kinase (PI 3-kinase) activity in skeletal muscle.

High circulating fats prevent insulin from activating a key enzyme (PI 3-kinase) required for glucose uptake. This molecular blockage is a primary reason why high fat states lead to insulin resistance.

Calorie restriction extends lifespan in model organisms and mammals, and this extension requires the NAD-dependent deacetylase activity of sirtuins (specifically Sir2/SIRT1).

Calorie restriction promotes longevity, but it works through specific biological mechanisms involving sirtuins. While the paper focuses on mechanisms, the implication is that maintaining metabolic health and NAD levels is key. For humans, this suggests that dietary patterns mimicking calorie restriction (like intermittent fasting) might activate these pathways, though direct lifespan extension in humans is not yet proven.

SIRT4 regulates amino acid-stimulated insulin secretion (AASIS) by ADP-ribosylating and inhibiting glutamate dehydrogenase (GDH), linking energy limitation to insulin release.

SIRT4 helps the body decide when to release insulin in response to protein intake. During calorie restriction, SIRT4 levels drop, allowing more insulin to be released in response to amino acids, shifting the source of insulin triggers from carbohydrates to proteins.

Fasting plasma ghrelin concentrations are negatively correlated with body mass index (BMI), with lower levels in obesity and higher levels in anorexia nervosa, indicating that chronic positive energy balance suppresses ghrelin secretion.

Your body's hunger hormone (ghrelin) levels are biologically tuned to your long-term weight status. In obesity, baseline ghrelin is suppressed, which may contribute to the difficulty in losing weight or maintaining loss, as the hormonal drive to eat is chronically altered. This is a physiological adaptation, not a failure of willpower.

Elevated expression of the transcriptional coregulator Prdm16 in subcutaneous white adipose tissue induces a brown fat-like gene program, increasing energy expenditure and protecting against high-fat diet-induced obesity and glucose intolerance.

This research identifies Prdm16 as a key regulator that allows subcutaneous fat to burn energy like brown fat. While this is currently a mouse model finding, it suggests that therapies targeting this pathway could help combat obesity and insulin resistance by increasing energy expenditure. For now, maintaining a healthy weight through diet and exercise remains the primary strategy, but this mechanism highlights the importance of subcutaneous fat health.

Low birth weight combined with rapid postnatal weight gain increases the risk of insulin resistance and type 2 diabetes in adulthood.

For those with a history of low birth weight, prioritize maintaining a healthy weight and metabolic health through balanced nutrition and physical activity to mitigate the additive risk of insulin resistance and type 2 diabetes.

Leptin-replacement therapy reduces liver volume and improves liver function tests in patients with lipodystrophy.

Leptin therapy shrinks enlarged livers and improves liver enzymes in patients with lipodystrophy, reducing the risk of liver disease.

Adipose tissue hypoxia in obesity, driven by reduced blood perfusion rather than systemic oxygen deficiency, causes dysregulated adipocytokine production (specifically decreased adiponectin and increased PAI-1) through endoplasmic reticulum (ER) stress and mRNA instability.

Obesity creates a low-oxygen environment in fat tissue that disrupts healthy hormone production. This disruption contributes to insulin resistance and metabolic issues. While this paper doesn't offer a direct treatment, it highlights that reducing fat mass can alleviate tissue hypoxia, thereby restoring normal adipocytokine function and improving metabolic health.

Elevated triglycerides serve as a marker for increased numbers of triglyceride-rich lipoprotein (TRL) remnants, which are directly atherogenic by penetrating the arterial wall, accumulating in plaques, and promoting inflammation and thrombosis.

High triglycerides are not just a number; they represent particles that can physically enter artery walls and cause inflammation. Keeping triglycerides low (below 150 mg/dL) helps prevent these particles from building up in your arteries.

Elevated plasma levels of asymmetric dimethylarginine (ADMA) impair endothelial function by competitively inhibiting nitric oxide synthase, leading to reduced vasodilation in hypercholesterolemic individuals.

If you have high cholesterol, your body may produce more ADMA, a substance that blocks blood vessel relaxation. This happens even before symptoms appear. Administering L-arginine can reverse this blockage and restore normal blood flow, suggesting that managing cholesterol is critical to preventing this specific biochemical imbalance.

Pharmacological administration of cholecystokinin (CCK) reduces meal size acutely in humans and animals, but chronic administration fails to produce sustained weight loss due to compensatory increases in meal frequency.

While CCK reduces meal size when given, the body compensates by eating more often, so it doesn't help with long-term weight loss. This highlights why simply trying to 'stop eating' with one-off interventions often fails.

Activation of PPARγ by synthetic thiazolidinediones (glitazones) improves insulin sensitivity and reduces blood glucose in type 2 diabetes, but carries significant cardiovascular risks (e.g., rosiglitazone) and side effects (weight gain, edema).

If prescribed a PPARγ agonist for diabetes, understand that while they improve insulin sensitivity, the specific drug matters. Pioglitazone may offer cardiovascular benefits, whereas rosiglitazone has been linked to increased heart risks. Discuss side effects like weight gain and edema with your doctor.

Dietary omega-3 polyunsaturated fatty acids (specifically EPA) combined with aspirin or other NSAIDs generate novel anti-inflammatory lipid mediators (18R-HEPE, 5,12,18R-triHEPE, and 15-epi-LXA5) via transcellular processing involving COX-2 and leukocyte 5-lipoxygenase, which inhibit polymorphonuclear leukocyte (PMN) transendothelial migration and infiltration.

If you take omega-3 supplements (specifically EPA) and have inflammation (which upregulates COX-2), your body can convert these fats into potent anti-inflammatory signals, especially if you take aspirin or certain other NSAIDs. These signals actively stop immune cells from migrating to inflamed tissues. This suggests that the benefit of omega-3s is not just passive competition but active creation of anti-inflammatory mediators.

Basal (resting) hormone measurements, including cortisol and testosterone/cortisol ratios, are not useful for diagnosing overtraining syndrome or distinguishing between well-adapted and overtrained athletes.

Do not rely on resting blood tests for testosterone or cortisol to diagnose overtraining. These levels are influenced by many factors and do not reliably distinguish between healthy adaptation and overtraining. Focus on performance metrics and subjective feelings of fatigue.