Browse the evidence

Fasting and metabolic states modulate olfactory sensitivity by upregulating metabolic hormone receptors (insulin, leptin, NPY) in the olfactory mucosa and bulb, enhancing odor detection during hunger.

If you feel your sense of smell is sharper when you are hungry, this is a normal biological response. Your body upregulates receptors for hormones like insulin and leptin in your nose to help you find food. This is not a flaw in your discipline; it is a designed feature of your metabolic system.

Gastric bypass surgery leads to sustained weight loss, partly mediated by a decrease in circulating ghrelin and an increase in peptide YY (PYY) and glucagon-like peptide-1 (GLP-1) levels.

Gastric bypass surgery causes sustained weight loss, partly by altering gut hormones (lower ghrelin, higher PYY/GLP-1). This hormonal shift offers a model for developing non-surgical obesity treatments that replicate this profile.

Increasing long-chain omega-3 intake has little or no effect on the risk of developing type 2 diabetes or on glucose metabolism markers (HbA1c, fasting glucose, insulin, HOMA-IR).

If you are taking omega-3 supplements hoping to lower your blood sugar or prevent diabetes, this review suggests you are unlikely to see those specific benefits. The evidence shows no significant change in diabetes risk or glucose levels. Continue taking them if you like for general health, but do not rely on them for diabetes management.

Current cigarette smoking is associated with a metabolically adverse fat distribution profile characterized by higher central adiposity (waist circumference, waist-hip ratio) and lower peripheral adiposity (hip circumference) compared to never smokers, even after adjusting for BMI and lifestyle confounders.

If you smoke, do not rely on it for weight management. While you might weigh less than a non-smoker, your body stores fat in a more dangerous pattern around your waist rather than your hips. This increases your risk for metabolic issues regardless of your BMI. Quitting smoking is the best step for long-term health, even if it leads to some weight gain, as it helps normalize fat distribution over time.

The BclI polymorphism (G-allele) of the glucocorticoid receptor gene is associated with increased sensitivity to glucocorticoids, resulting in lower body mass index (BMI) and lean body mass in elderly populations.

If you are older and find it difficult to maintain muscle mass despite stable weight, your body may be genetically hypersensitive to cortisol. This sensitivity can lead to muscle loss (lower lean mass) rather than fat gain. Focus on resistance training to preserve lean mass, as your body may be more prone to catabolic effects from stress or endogenous cortisol.

Adipose tissue serves as a significant extra-gonadal source of estrogen through the conversion of androgens, meaning that body fatness directly influences the quantity and potency of circulating estrogen and thus reproductive ability.

Body fat is not just stored energy; it is an active endocrine organ that produces estrogen. Very low body fat levels can lead to estrogen deficiency, disrupting menstrual cycles and fertility.

Six weeks of CPAP therapy significantly reduces waking systolic and diastolic blood pressure and improves baroreceptor sensitivity in obese males with OSA, but does not alter insulin resistance, lipid profiles, or metabolic syndrome status within this timeframe.

If you are obese and have OSA, using CPAP nightly for at least 6 weeks will significantly lower your blood pressure and improve your heart's stress response. However, do not expect CPAP alone to fix your blood sugar, cholesterol, or weight in that short time; you must combine it with weight management strategies to address metabolic health.

Hepatic triglyceride content (IHCL) is significantly and positively correlated with central adiposity, specifically intra-abdominal and subcutaneous abdominal adipose tissue, independent of total body fat or BMI.

Your liver fat is closely tied to your abdominal fat, not just your total weight. Even if you are lean, high abdominal fat can lead to significant liver triglyceride accumulation. Conversely, losing abdominal fat is likely to reduce liver fat more effectively than focusing on total body weight alone. Non-invasive imaging like MRS can monitor this, but lifestyle changes targeting abdominal adiposity are the primary lever.

Obesity results from a failure of the central hypothalamic satiety mechanism (specifically the ventromedial nucleus) to inhibit the lateral feeding center, leading to hyperphagia, rather than from a simple failure of peripheral stomach sensations.

Focus on the quality and metabolic impact of food (specifically glucose utilization) rather than just volume or stomach sensations. The brain regulates intake based on how nutrients are processed, not just physical distension.

Short-term food intake regulation is driven by a 'glucostatic' mechanism where glucose utilization in the ventromedial hypothalamus triggers satiety, rather than blood glucose concentration alone.

Focus on how your body uses carbohydrates (glucose utilization) rather than just avoiding them. The brain's ability to process glucose signals satiety.

Transfeminine hormone therapy (estrogen + antiandrogens) induces feminizing physical changes including breast development, fat redistribution, and reduced body/facial hair, but does not significantly alter voice pitch.

Transfeminine hormone therapy will cause breast growth, fat redistribution to a female pattern, and reduced body/facial hair growth. It will NOT significantly lower your voice pitch. If voice pitch change is a priority, you will likely need voice training or surgery in addition to hormones. Breast development varies, with many reaching a plateau at a smaller cup size (AAA or less) within 6 months.

Testosterone supplementation in older men with low testosterone levels does not consistently improve muscle strength or functional ability, despite increasing lean body mass and decreasing fat mass.

If you are an older man with low testosterone, testosterone therapy may increase your lean body mass and decrease fat, but it is unlikely to make you stronger or improve your physical function. It does not replace the need for exercise, and the long-term safety and benefits for healthy older men remain unproven.

Weekly oral fecal microbiota transplantation (FMT) from lean donors does not significantly improve insulin sensitivity, body weight, or body composition in adults with obesity and mild-to-moderate insulin resistance over a 12-week period.

For adults with obesity and mild insulin resistance, receiving weekly oral FMT capsules from lean donors does not significantly improve insulin sensitivity, weight, or body composition over 12 weeks. While the treatment is safe and alters gut bacteria, it should not be expected to replace lifestyle interventions like diet and exercise for metabolic improvement.

Elevated circulating levels of branched-chain amino acids (Leu, Ile, Val) and aromatic amino acids (Phe, Tyr) are strongly associated with insulin resistance (HOMA-IR) in young, normoglycemic adults, with associations being significantly stronger in men and in women only when abdominally obese.

If you are young and healthy, high levels of certain amino acids in your blood may signal early insulin resistance, especially if you carry weight around your midsection. This is not a diagnosis of diabetes, but a signal to prioritize physical activity and metabolic health. The study suggests these markers are secondary to insulin resistance rather than the cause, so focusing on overall metabolic health (exercise, healthy fats) is more effective than restricting protein intake.

Genetic variants that regulate circulating amino acid and lipid levels generally do not cause insulin resistance, suggesting that elevated amino acids are likely secondary markers of insulin resistance rather than causal drivers.

Genetic evidence suggests that high amino acid levels in your blood are likely a symptom of insulin resistance, not the cause. This means you don't need to restrict protein intake to fix insulin resistance. Instead, focus on lifestyle factors like exercise and healthy fats that improve how your body uses insulin.

Genetic factors, particularly polymorphisms affecting neurotransmitter systems (dopamine, serotonin) and metabolic traits (BMI, insulin resistance), significantly increase the risk of developing eating disorders, with distinct genetic architectures for anorexia nervosa versus binge-type disorders.

If you have a family history of eating disorders, you may have a biological predisposition. This is not your fault, but it is a risk factor you can manage. Focus on early identification of symptoms and seek professional support if you notice changes in eating habits or body image, as genetic risk can be mitigated by environmental factors.

Childhood trauma, abuse, and neglect are strongly linked to the development of eating disorders, particularly Bulimia Nervosa and Binge Eating Disorder, through interactions with genetic susceptibility.

If you have experienced childhood trauma, you may be at higher risk for eating disorders. This risk is not inevitable, but it is significant. Trauma-informed therapy and support can help address the underlying emotional pain that may manifest as disordered eating.

Pharmacological inhibition of BCKDK using BT2 reduces plasma branched-chain amino acid (BCAA) and branched-chain alpha-keto acid (BCKA) levels, thereby attenuating obesity-associated insulin resistance in obese mice.

In obese individuals, high levels of branched-chain amino acids (BCAAs) and their metabolites contribute to insulin resistance. This study suggests that enhancing the body's ability to break down BCAAs (via BCKDK inhibition) improves insulin sensitivity. While BT2 is a drug, the findings support the idea that managing BCAA metabolism is key to treating obesity-related metabolic issues.

Elevated levels of branched-chain alpha-keto acids (BCKAs) impair insulin signaling by activating mTORC1, independent of BCAAs.

BCKAs, metabolites of BCAAs, directly impair insulin signaling by activating mTORC1. This suggests that managing BCAA metabolism is crucial for preventing insulin resistance, as BCKAs are not just inert byproducts but active contributors to metabolic dysfunction.

Resistin levels are increased in obesity and induce insulin resistance by inhibiting AMPK activity and increasing SOCS3 expression.

Resistin is a hormone that increases with obesity and contributes to insulin resistance by interfering with cellular energy sensors (AMPK). Reducing obesity can lower resistin levels and improve insulin sensitivity.

In healthy individuals consuming low-cholesterol diets, the absolute milligram amount of dietary cholesterol absorbed (not the efficiency of absorption) is strongly and independently correlated with fasting plasma insulin, C-peptide, and glucagon levels, serving as a marker for insulin resistance.

If you are healthy and eat a balanced diet, your body's ability to absorb cholesterol (efficiency) doesn't change much based on what you eat. However, the actual amount of cholesterol you absorb is linked to higher insulin levels. To manage insulin sensitivity, focus on the total amount of cholesterol and fat in your diet rather than trying to alter your body's absorption efficiency.

The ISI0,120 index of insulin sensitivity, derived from oral glucose tolerance test data, is an independent predictor of incident cardiovascular disease (CVD) risk, whereas the fasting-based HOMA-IR index is not independent of the metabolic syndrome.

If you are concerned about heart disease risk and have normal fasting glucose but other metabolic risk factors, a standard fasting insulin test (HOMA-IR) may not tell the whole story. This research suggests that how your body handles sugar after a meal (measured by ISI0,120 via an OGTT) provides independent information about cardiovascular risk that fasting tests miss. Discuss with your doctor whether an Oral Glucose Tolerance Test is warranted for comprehensive risk assessment, especially if you have family history or other metabolic syndrome components.

Late-onset hypogonadism (LOH) defined by sexual symptoms and total testosterone <8 nmol/liter is associated with significant end-organ deficits including lower hemoglobin, bone mineral density, and lean mass, whereas moderate LOH (8-11 nmol/liter) shows only modest tissue-level changes.

If you are an older man experiencing sexual dysfunction (ED, low libido) alongside fatigue or muscle loss, get your testosterone checked. If your levels are below 8 nmol/liter, you likely have Late-Onset Hypogonadism, which is linked to lower bone density, muscle mass, and hemoglobin. However, if your levels are between 8-11 nmol/liter, your metabolic risks are likely due to weight and age, not testosterone, so focus on weight management rather than hormone therapy.

Acute total sleep deprivation enhances brain activation in the anterior cingulate cortex in response to hedonic food stimuli, increasing subjective appetite ratings independent of fasting plasma glucose levels.

If you are sleep-deprived, your brain's reward system becomes hypersensitive to food cues, specifically activating the anterior cingulate cortex. This happens regardless of your actual blood sugar levels. To mitigate this, prioritize getting adequate sleep, as acute sleep loss directly amplifies the neural drive to consume food.