Browse the evidence

Testosterone supplementation increases fat-free mass and maximal voluntary strength in hypogonadal men, regardless of whether the dose is physiologic or supraphysiologic.

If you are a man with clinically low testosterone, testosterone replacement therapy will reliably increase your muscle mass and strength. This holds true whether you are older, HIV-positive, or even if you have normal testosterone levels but take high doses. However, do not expect this to improve your endurance running or cycling performance, nor does it guarantee a reduction in falls for older adults. Consult a doctor for blood tests before considering treatment.

Short-acting GLP-1 receptor agonists (exenatide twice daily, lixisenatide) produce greater reductions in postprandial glucose than long-acting agents (liraglutide, dulaglutide, exenatide once weekly) due to delayed gastric emptying, whereas long-acting agents provide superior fasting glucose control.

If you struggle with blood sugar spikes after meals, short-acting GLP-1 drugs (taken twice daily or before meals) may work better for you. If your main issue is high fasting blood sugar in the morning, long-acting GLP-1 drugs (taken once daily or weekly) are likely more effective. Discuss these options with your doctor to match the drug's mechanism to your specific glucose pattern.

Higher proportions of saturated fatty acids (palmitic acid) and lower proportions of linoleic acid in serum lipids and skeletal muscle phospholipids are strongly associated with reduced insulin sensitivity in observational studies.

Your blood fat profile (specifically high saturated fat and low linoleic acid) is a strong warning sign for insulin resistance. While changing fats won't 'cure' resistance quickly, maintaining a profile rich in unsaturated fats is associated with better insulin sensitivity.

Metformin treatment in women with PCOS leads to regularization of the menstrual cycle, reduction in hyperandrogenism, and improvement in cardiovascular risk factors.

If you have PCOS, ask your doctor about metformin. It is the most common medication used for this condition because it helps fix the underlying insulin resistance. This can help restore regular periods, lower male hormone levels, and improve heart health risks. Lifestyle changes like diet and exercise are also recommended, especially if you are overweight.

Acute intranasal insulin administration reduces food intake in men but not in women, indicating higher sensitivity of men to central anorexigenic insulin signaling.

If you are a healthy man, acute intranasal insulin may help you eat less, but this effect does not appear to exist for women. This suggests that treatments targeting central insulin signaling for weight loss may need to account for gender-specific biological responses.

Calcium supplementation combined with Vitamin D reduces hip fracture incidence in elderly women (mean age 84) and non-vertebral fracture rates in older adults (mean age 71).

If you are elderly, taking both Calcium and Vitamin D together is more effective for preventing hip fractures than Calcium alone. This combination helps correct Vitamin D status and lowers PTH, which protects bone.

Regular exercise training suppresses chronic systemic inflammation by inhibiting the infiltration of inflammatory cells (neutrophils and M1 macrophages) into adipose tissue and skeletal muscle, thereby preventing tissue fibrosis and organ dysfunction associated with obesity and aging.

Engage in regular, moderate physical activity (like walking) rather than avoiding exercise due to fear of inflammation. This helps clear inflammatory cells from fat and muscle tissue, protecting your organs from age-related damage.

In Type 1 Diabetes (T1D), obesity and weight gain are increasingly common complications of intensive insulin therapy, contributing to insulin resistance and cardiovascular risk, but GLP-1 agonists and SGLT2 inhibitors show promise in mitigating weight gain.

If you have Type 1 Diabetes and are gaining weight despite insulin therapy, discuss adjunctive treatments like GLP-1 agonists or SGLT2 inhibitors with your doctor. These may help reduce insulin requirements and manage weight, addressing a common side effect of intensive insulin therapy.

Men experience significantly greater absolute muscle hypertrophy than women in response to heavy resistance strength training, regardless of age.

Men will likely gain more absolute muscle mass than women from the same training program due to physiological differences. This is normal. Women should focus on relative improvements and strength gains rather than comparing absolute size to men.

Mitochondrial dysfunction in adipose tissue, characterized by reduced oxidative capacity and increased ROS, is a primary driver of insulin resistance and metabolic disease.

Maintaining healthy mitochondrial function in fat cells is crucial for managing insulin sensitivity and preventing metabolic diseases. Strategies to support this include regular exercise, caloric restriction, and potentially specific dietary compounds or medications that target mitochondrial health, as these can improve the body's ability to regulate glucose and lipids.

Reduction of SirT1 expression in adipose tissue causes macrophage recruitment and inflammation, while maintaining or increasing SirT1 levels prevents this inflammation.

In obesity, SirT1 levels in fat drop, which triggers inflammation and immune cell buildup. Restoring normal SirT1 levels (e.g., through caloric restriction or weight loss) helps prevent this. However, artificially boosting SirT1 in lean individuals might not help and could potentially cause issues, so natural regulation via energy balance is key.

Post-resistance exercise ingestion of ~6g amino acids and ~35g glucose yields a net muscle protein synthesis response roughly equivalent to the sum of their independent effects, with no synergistic amplification.

After your resistance workout, you can consume amino acids (or protein) and carbohydrates together, or separately, and get roughly the same muscle-building benefit. The combination does not provide a 'super' effect beyond what each provides on its own. Focus on getting your protein in; adding carbs is optional for this specific additive effect, though it may help with recovery or performance in other contexts.

Roux-en-Y gastric bypass (RYGB) surgery reduces brain-hedonic responses to high-calorie foods compared to gastric banding (BAND) surgery, mediated by altered gut anatomy and increased anorexigenic hormones.

If you are considering bariatric surgery, understand that Roux-en-Y gastric bypass (RYGB) works differently than gastric banding. RYGB not only restricts food intake but also changes gut hormones (GLP-1, PYY) that reduce the brain's reward response to high-calorie foods. This neurohormonal shift may contribute to better long-term weight loss and healthier eating habits compared to gastric banding. Discuss these specific hormonal mechanisms with your surgeon to make an informed choice.

Consumption of liquid preloads containing 50g of whey, soy, or gluten protein reduces subsequent ad libitum energy intake by approximately 10% compared to an equicaloric glucose preload, independent of the subject's BMI status.

To reduce your next meal's intake, consume a liquid preload containing about 50g of protein (whey, soy, or gluten) roughly 3 hours before you plan to eat. This strategy works for both lean and overweight men and reduces subsequent food intake by about 10% compared to drinking a sugary drink of the same size and calories. The type of protein matters less than the fact that it is protein in liquid form.

GLP-1 receptor agonists (Liraglutide, Semaglutide, Dulaglutide) significantly reduce liver fat content and improve liver enzymes in patients with Type 2 Diabetes and NAFLD, with Semaglutide showing histological resolution of NASH in Phase II trials.

If you have Type 2 Diabetes and NAFLD, ask your doctor about GLP-1 receptor agonists like Semaglutide or Liraglutide. These injectable medications have been shown in clinical trials to reduce liver fat and improve liver inflammation, in addition to helping with weight and blood sugar control.

SGLT2 inhibitors (Empagliflozin, Dapagliflozin, Ipragliflozin) improve liver fat content and liver enzymes in patients with Type 2 Diabetes and NAFLD, with some evidence of improving liver fibrosis.

If you have Type 2 Diabetes and NAFLD, SGLT2 inhibitors like Empagliflozin or Dapagliflozin may help reduce liver fat and improve liver enzymes. Discuss these options with your doctor, especially if you are already managing your blood sugar with other medications.

Tournament wrestling involving 6% body weight loss followed by multiple matches over two days causes progressive, significant reductions in lower body power and upper body isometric strength, alongside elevated physiological stress markers (testosterone, cortisol, lactate, norepinephrine, epinephrine, and plasma osmolality).

If you are a wrestler, be aware that losing 6% of your body weight and then competing in multiple matches over two days will significantly reduce your strength and power. Your body will also experience high levels of stress, indicated by changes in hormones and metabolic markers. To maintain performance, consider strategies that minimize extreme weight loss and prioritize recovery between matches.

Exercise promotes glucose uptake in skeletal muscle via an insulin-independent mechanism involving AMPK activation, distinct from the insulin signaling pathway.

Exercise helps your muscles take up glucose directly, even if your insulin sensitivity is low. This happens through the activation of AMPK, a cellular energy sensor. This is why physical activity is beneficial for blood sugar control regardless of insulin resistance status.

Elevated serum androstenedione (A) is a stronger predictor of insulin resistance and metabolic dysfunction in women with Polycystic Ovary Syndrome (PCOS) than serum testosterone (T), with high A levels correlating to lower insulin sensitivity regardless of T status.

For women with PCOS, relying solely on testosterone levels may miss those at highest risk for insulin resistance and metabolic issues. Measuring androstenedione alongside testosterone provides a more complete picture of androgen excess and better predicts metabolic health risks.

PCOS patients with high androstenedione and normal testosterone (HA/NT) exhibit significantly higher insulin resistance and dysglycemia rates compared to those with normal levels of both androgens (NA/NT), despite having normal testosterone.

If you have PCOS and your testosterone is normal, you are not automatically clear of metabolic risk. If your androstenedione is high, you may still have insulin resistance and a higher risk of developing diabetes, so monitoring glucose metabolism is important.

Menstrual dysfunction (MD) in female endurance athletes is associated with lower resting metabolic rate (RMR) compared to eumenorrheic athletes, independent of energy availability status.

If you are a female endurance athlete and your menstrual cycle has become irregular or stopped, do not assume it is normal. This is a sign that your body is under stress, possibly from low energy intake, and your metabolism may be slowing down. Seek medical evaluation to assess your energy availability and hormonal health.

Deliberate overreaching via progressive overload training in team sport athletes causes significant reductions in muscular strength, power, and endurance, primarily driven by increased muscle damage and a shift toward a catabolic state.

If you are feeling consistently fatigued and your performance is dropping despite hard training, you may be overreached. The solution is not to train harder, but to reduce your training volume and intensity for about a week (tapering). This allows your body to recover from muscle damage and hormonal imbalances, often resulting in improved strength, power, and endurance once you return to normal training.

A decreased testosterone-to-cortisol (T/C) ratio and elevated creatine kinase (CK) activity are biochemical markers indicating a catabolic state and muscle damage associated with overreaching.

Monitoring hormonal balance can help identify when you are overtrained. A drop in the testosterone-to-cortisol ratio and high creatine kinase levels indicate your body is in a catabolic (breaking down) state. If you have access to blood testing, these markers can guide your recovery needs. If not, focus on subjective feelings of fatigue and performance drops as proxies.

Erectile dysfunction in diabetic men is strongly associated with cardiovascular disease, often preceding coronary artery disease by 2-5 years, making ED a predictor of cardiac risk.

Erectile dysfunction is not just a sexual problem; it is a warning light for your heart. In diabetic men, ED often appears 2-5 years before heart disease symptoms. If you experience ED, request a cardiovascular risk assessment, as treating the underlying vascular issues can prevent future cardiac events.