Browse the evidence

Acute creatine monohydrate supplementation reduces whole-body protein breakdown and leucine oxidation in men, but does not increase mixed-muscle protein synthesis.

If you are a man, acute creatine loading (20g/day for 5 days) may help preserve muscle protein by reducing breakdown, without necessarily increasing synthesis rates. This effect was not seen in women in this study. Ensure you are well-hydrated and follow a loading protocol if you want to maximize muscle creatine stores.

Glucose and insulin directly regulate fat oxidation by inhibiting the entry of long-chain fatty acids into the mitochondria, independent of plasma fatty acid availability.

High carbohydrate intake combined with insulin secretion can directly shut down fat oxidation in muscles, even if you are not eating fat. This happens because insulin and glucose inhibit the transport of fat into the mitochondria where it is burned. To maximize fat oxidation, one must manage carbohydrate intake to avoid high insulin spikes, as simply eating low-fat does not guarantee fat burning if insulin levels are elevated.

Combining metformin (2,000 mg/day) with exercise training does not enhance whole-body insulin sensitivity in individuals with prediabetes compared to exercise training alone, and may blunt the full effect of exercise.

If you have prediabetes, exercise training significantly improves your insulin sensitivity. Adding metformin does not provide extra benefit for insulin sensitivity and might actually reduce the gains you get from exercise. Focus on consistent exercise (aerobic and resistance) as the primary driver for improving insulin sensitivity, and discuss with your doctor whether metformin is necessary for other reasons (like weight loss or diabetes prevention) rather than expecting it to boost exercise benefits.

Lean individuals (BMI < 25 kg/m² for Caucasians, < 23 kg/m² for Asians) with NAFLD face a higher risk of severe liver disease and mortality compared to obese NAFLD patients, challenging the belief that lean NAFLD follows a benign clinical course.

If you have fatty liver but are not overweight, do not assume your condition is mild. You are at higher risk for severe liver complications than obese patients with fatty liver. You require regular monitoring for fibrosis progression and metabolic health, just as strictly as obese patients.

In lean individuals, the PNPLA3 rs738409 G allele is an independent predictor of NAFLD and NASH severity, whereas it is not associated with histological severity in obese patients.

If you are lean and have fatty liver, genetic testing for PNPLA3 may help predict your risk of progression to NASH. This information can guide how frequently you need liver biopsies or advanced imaging, even if you maintain a healthy weight.

Thyroid hormone (TH) signaling is a primary regulator of basal metabolic rate and energy expenditure, with severe hypothyroidism capable of slowing total body energy expenditure by up to 50%.

Your body's metabolic rate is not fixed; it is actively regulated by thyroid hormones. In states of low energy availability (like fasting or severe hypothyroidism), your body slows down energy expenditure to conserve resources. Understanding this hormonal link helps explain why metabolic rate can fluctuate based on energy intake and health status.

Brown adipose tissue (BAT) is a targetable site for adaptive thermogenesis in adult humans, where thyroid hormone signaling is required for its differentiation and function, specifically through the induction of UCP1 expression.

Adult humans can possess metabolically active brown fat, which helps burn energy as heat. This process is regulated by thyroid hormones and involves a protein called UCP1. While not a primary weight-loss strategy for everyone, understanding BAT highlights the complexity of fat tissue and its role in metabolism.

Aging is associated with profound changes in epigenetic patterns, including genomic hypomethylation and promoter-specific hypermethylation, which may contribute to age-related diseases like cancer and neurodegeneration.

Understand that aging involves natural epigenetic shifts. While you cannot stop aging, dietary choices can influence these epigenetic patterns, potentially supporting healthy aging and reducing disease risk.

In the context of Nonalcoholic Fatty Liver Disease (NAFLD), hepatic triglyceride accumulation acts as a hepatoprotective buffering mechanism against lipotoxicity; inhibiting triglyceride synthesis (e.g., via DGAT2 inhibition) exacerbates liver damage and fibrosis despite reducing steatosis.

If you have fatty liver, simply trying to 'burn off' liver fat without addressing the underlying insulin resistance and free fatty acid overflow might be counterproductive. The liver uses triglyceride storage as a safety buffer. Focus on reducing the influx of fatty acids (through caloric restriction and managing insulin resistance) rather than aggressive interventions that might disrupt this buffering capacity, as this can worsen liver inflammation and fibrosis.

Pharmacological inhibition of hypothalamic Sirt1 reduces food intake and alters melanocortin system synaptic connectivity by decreasing Agrp neuron activity.

This research identifies a specific brain pathway where inhibiting the enzyme Sirt1 reduces food intake in mice. It does not currently translate to a human supplement or drug recommendation, as the effects are specific to hypothalamic neurons and involve complex neural circuitry. Caution is advised against interpreting 'Sirt1 inhibition' as a general weight-loss strategy without understanding the specific neural context.

Sirt1 activity in Agrp neurons is required for normal ghrelin-induced neuronal firing and food intake.

This finding highlights the critical role of Sirt1 in Agrp neurons for processing hunger signals (ghrelin). It suggests that genetic variations or dysfunction in this specific pathway could impact hunger regulation and body weight, but it does not currently offer a direct intervention for humans.

Central nervous system (CNS) activation of GLP-1 receptors by peptides such as GLP-1, oxyntomodulin (OXM), or glucagon (GCG) directly increases brown adipose tissue (BAT) thermogenesis via sympathetic nervous system signaling, independent of changes in food intake or peripheral insulin sensitivity.

Central GLP-1 receptor activation (via drugs like GLP-1 agonists) boosts brown fat activity to burn energy, separate from just making you eat less. This mechanism requires the drug to act on the brain, not just the gut.

Oxyntomodulin (OXM) requires functional GLP-1 receptors in the CNS to induce brown adipose tissue thermogenesis, despite also binding to glucagon receptors.

If using Oxyntomodulin (or dual agonists with strong OXM activity), the GLP-1 receptor pathway is essential for activating brown fat. Simply activating glucagon receptors is not enough to trigger this specific fat-burning mechanism.

Germline loss-of-function PTEN mutations cause constitutive insulin sensitivity, resulting in significantly lower fasting insulin levels and higher glucose disposal rates despite the presence of obesity.

This finding highlights that metabolic health (insulin sensitivity) is genetically regulated and can be preserved in obesity if specific pathways (like PTEN) are active. It suggests that BMI alone is an insufficient predictor of metabolic risk for all individuals, particularly those with specific genetic profiles.

Thyroid hormone (T3) accelerates skeletal muscle contraction and relaxation rates by stimulating the expression of fast myosin heavy chain isoforms (MYH2, MYH1, MYH4) and sarcoplasmic reticulum Ca2+ ATPase (SERCA1a).

If you have hypothyroidism, treating it to normal levels may help restore normal muscle speed and function, as thyroid hormone directly controls the proteins responsible for contraction speed. However, for healthy individuals, manipulating thyroid levels is not a standard or safe performance enhancement strategy.

Thyroid hormone (T3) regulates skeletal muscle myogenesis by controlling intracellular T3 levels via D2 and D3 deiodinases, which determines satellite cell proliferation and differentiation.

Proper thyroid function is necessary for effective muscle repair and regeneration after injury or exercise. If you have thyroid issues, addressing them may improve your body's ability to repair muscle tissue.

Higher early adult BMI (ages 18-30) is inversely associated with breast cancer risk in both pre- and postmenopausal women, suggesting a protective effect of higher adiposity during young adulthood.

Maintain a healthy weight during young adulthood (18-30), as higher early adult BMI may offer some protection against breast cancer later in life. However, avoid adult weight gain, which increases risk.

In normotensive premenopausal women, visceral adipose tissue (VAT) and insulin resistance are directly associated with elevated plasma aldosterone levels, independent of plasma renin activity.

For women, reducing visceral fat through weight loss is likely to lower aldosterone levels, which may help manage blood pressure and cardiovascular risk, independent of standard kidney-based hormone regulation. This suggests that visceral fat reduction has specific hormonal benefits for women that may not be as pronounced in men.

Fetal programming and early-life under-nutrition (stunting) increase vulnerability to obesity and metabolic syndrome when individuals are exposed to modern, energy-dense diets during the nutrition transition.

For individuals with a history of childhood stunting or under-nutrition, standard weight loss advice may be less effective due to metabolic programming. Interventions should focus on high-quality nutrient density rather than just caloric restriction, and early-life nutrition is critical to prevent this vulnerability.

Regulatory T (Treg) cells exert an attenuating effect on insulin resistance and hepatic inflammation in NAFLD and obesity, primarily through the secretion of inhibitory cytokines IL-10 and TGF-beta and PPAR-gamma-dependent functionality.

In obesity and NAFLD, the body's natural regulatory T cells (Tregs) are often depleted or dysfunctional, contributing to insulin resistance and liver damage. Restoring Treg function (e.g., via PPAR-gamma agonists like pioglitazone in clinical settings) can improve glucose tolerance and reduce liver inflammation. Lifestyle interventions that reduce adipose tissue inflammation may help preserve Treg numbers.

Th17 cells promote liver inflammation, fibrosis, and insulin resistance in NAFLD and obesity, primarily through IL-17 secretion which stimulates pro-inflammatory cytokine release and hepatic stellate cell activation.

High levels of Th17 cells and IL-17 are associated with worse insulin resistance and liver fibrosis in obesity and NAFLD. Reducing systemic inflammation through weight loss and metabolic control may lower Th17 activity, thereby improving insulin sensitivity and slowing liver disease progression.

Long-acting Fc-fusion GDF15 molecules reduce body weight and improve metabolic profiles in obese models by delaying gastric emptying, altering food preference, and activating area postrema neurons.

This research suggests that engineered GDF15 therapies could effectively treat obesity by slowing digestion and changing food preferences via brain signaling. While currently in preclinical stages, the weekly dosing schedule of these long-acting variants offers a promising alternative to daily oral medications for metabolic disorders.

In euthyroid obese individuals, elevated serum TSH is an adaptive physiological response to increased thyroid hormone disposal driven by larger body size, rather than primary hypothyroidism.

If you are obese but your thyroid hormones (T3/T4) are normal, a slightly high TSH is likely just your body's natural way of managing a larger size. It usually goes away when you lose weight. Current evidence does not support using thyroid medication to treat this isolated high TSH in obese people.

Leptin acts as a critical signal from adipose tissue to the hypothalamus to regulate the hypothalamus-pituitary-thyroid axis, specifically by stimulating TRH expression and TSH secretion during energy sufficiency.

Your body uses leptin (a hormone from fat cells) to tell your brain how much energy you have. When you fast or lose weight, leptin drops, signaling your brain to slow down thyroid function to save energy. This is a normal survival mechanism.