Browse the evidence

Acute post-exercise increases in systemic hormones (testosterone, GH, IGF-1) are not related to muscle hypertrophy following resistance training.

Stop worrying about how much your hormones spike after a workout. The acute rise in testosterone or growth hormone does not predict how much muscle you will gain. Focus on consistent training and recovery instead of trying to maximize hormonal spikes.

Ketogenic diets increase LDL cholesterol and total cholesterol, which may accelerate atherosclerosis and increase cardiovascular disease risk, despite improving triglycerides and HDL.

Monitor your LDL cholesterol closely when starting a ketogenic diet. While your triglycerides may drop and HDL rise, your LDL may increase significantly. If you have a history of cardiovascular disease or high baseline LDL, consult your provider, as this increase may pose a risk. Consider shifting fat sources to plant-based options (nuts, vegetables) to potentially mitigate LDL elevation.

Adding carbohydrates to a sufficient protein dose post-exercise does not further increase muscle protein synthesis in young men.

You don't need to eat carbs after your workout to build muscle, as long as you've eaten enough protein (20-25g). Carbs won't hurt, but they won't build extra muscle either. Eat them if you want to replenish energy for your next session.

In obese and noninsulin-dependent diabetic subjects, the thermic effect of infused glucose and insulin is significantly decreased or abolished due to a greater suppression of hepatic gluconeogenesis and lower glucose storage rates compared to normal-weight subjects.

If you are obese or have type 2 diabetes, your body may not generate as much heat (energy expenditure) in response to eating carbohydrates as a lean person's would. This is largely due to how your liver handles glucose production (gluconeogenesis) and storage under the influence of insulin. Improving insulin sensitivity through weight loss and metabolic health management can help restore this normal thermogenic response.

GIP promotes lipogenesis (fat storage) in adipose tissue, while GLP-1 promotes lipolysis (fat breakdown) indirectly via sympathetic nervous system activation.

GIP helps store fat in adipose tissue, while GLP-1 helps break it down. Dual agonists balance these effects to improve overall metabolic health.

Acute post-exercise elevations in growth hormone (GH) and cortisol are weakly correlated with gains in muscle fiber cross-sectional area (hypertrophy) but show no association with strength gains.

Do not design your workout based on the hope of a massive hormonal spike. The acute rise in testosterone or growth hormone after a set does not predict how much muscle you will gain. Focus on progressive overload and consistent training volume instead. The 'pump' or feeling of hormonal surge is not a reliable indicator of effective hypertrophy stimulus.

Insulin resistance in obesity causes a decreased thermic effect of glucose by limiting the rate of glucose uptake and storage, rather than by an intrinsic defect in thermogenic efficiency.

If you are obese, your body may not burn as many calories from a meal as a lean person's because insulin resistance slows down how fast your body stores glucose. This isn't a permanent defect; it's a rate-limiting step. Improving your insulin sensitivity (through exercise, weight loss, or diet) can help normalize how your body handles energy from food.

Menstrual cycle phase does not appreciably influence acute strength performance or chronic adaptations (strength/hypertrophy) to resistance exercise training in naturally cycling women.

Do not restrict your training volume, intensity, or frequency based on your menstrual cycle phase. The current scientific consensus indicates that hormonal fluctuations across the cycle do not significantly impact your ability to build strength or muscle. Focus on consistent, high-quality resistance training regardless of where you are in your cycle. If you experience menstrual symptoms that affect your well-being, adjust for comfort, not for perceived biological incapacity.

Systemic inflammation and HPA-axis dysregulation are biological mechanisms mediating the link between high body weight and psychological distress.

Understand that biological factors like inflammation and stress hormone dysregulation contribute to the link between obesity and depression. This is not just 'in your head' but has a physical basis.

Bariatric surgery induces early, pronounced improvements in hepatic and peripheral insulin sensitivity and glycemic control that occur independently of significant weight loss, primarily through anatomical remodeling of the gastrointestinal tract.

If you have severe obesity and type 2 diabetes, bariatric surgery can resolve your diabetes through hormonal changes in your gut, not just by making you smaller. This happens quickly, often before you lose much weight. Consult a multidisciplinary unit to see if you are a candidate.

GLP-1 receptor agonists (specifically liraglutide and dulaglutide) are associated with a statistically significant increase in the risk of overall thyroid disorders compared to placebo or other interventions, although they do not significantly increase the risk of specific conditions like thyroid cancer, hyperthyroidism, or hypothyroidism.

If you are taking a GLP-1 medication like liraglutide or dulaglutide, be aware that there is a slightly higher statistical risk of developing 'overall thyroid disorders' compared to those not taking the drug. However, this does not appear to increase your risk of thyroid cancer or major thyroid dysfunction. Standard monitoring is advised, but the fear of cancer based on animal studies is not supported by large human clinical trials.

Among specific GLP-1 receptor agonists, liraglutide and dulaglutide show a statistically significant increase in the risk of overall thyroid disorders, whereas semaglutide, lixisenatide, and exenatide do not show a significant effect.

Not all GLP-1 medications affect the thyroid equally. If you are concerned about thyroid health, liraglutide and dulaglutide have shown a statistically significant increase in overall thyroid disorders in large trials, whereas semaglutide, lixisenatide, and exenatide have not shown this significant risk. Discuss these differences with your provider when choosing a specific agent.

Tirzepatide requires GIP receptor (GIPR) activation to stimulate insulin secretion in human islets, as blocking GIPR consistently reduces this response.

Tirzepatide's effectiveness in lowering blood sugar relies on its ability to activate the GIP receptor, not just the GLP-1 receptor. In human tissue, blocking the GIP receptor stops tirzepatide from stimulating insulin, proving this second pathway is essential for its full benefit.

Tirzepatide stimulates glucagon secretion in human islets primarily through GIP receptor activation, which overrides the glucagon-suppressing effect of GLP-1 receptor activation.

Tirzepatide increases glucagon secretion via the GIP receptor, which might seem counterintuitive for a diabetes drug. However, this is a normal physiological response to nutrient sensing, and the drug's overall effect is still a significant reduction in blood glucose due to its powerful insulin-stimulating effects.

Tirzepatide stimulates insulin secretion in mouse islets predominantly through the GLP-1 receptor, with minimal GIP receptor contribution at therapeutic doses.

Research on tirzepatide using mice may not fully reflect how it works in humans, as mice require much higher doses for GIP receptor activation. This highlights the importance of human-specific studies for understanding the drug's full mechanism.

Treatment with GLP-1 receptor agonists (specifically Liraglutide and Semaglutide) is associated with a significantly increased risk of developing psychiatric disorders, including major depression, anxiety, and suicidal behavior, in patients with obesity.

If you are taking or considering GLP-1 medications like Ozempic or Wegovy for obesity, be aware that studies link these drugs to a higher risk of depression, anxiety, and suicidal thoughts, especially with long-term use. Discuss your mental health history with your doctor before starting, and monitor your mood closely. If you experience worsening depression or suicidal thoughts, contact your healthcare provider immediately.

Melanin-concentrating hormone (MCH) neurons in the LHA promote feeding and general intake behavior, while their blockade can increase energy expenditure and promote weight loss.

Research into MCH receptors shows potential for treating obesity by reducing food intake and increasing energy expenditure. However, current treatments are not yet available for humans, and lifestyle changes remain the primary strategy.

Orexin (OX) neurons in the LHA promote feeding, arousal, and physical activity, and their disruption is linked to sleep disorders like narcolepsy.

Orexin neurons are critical for both wakefulness and energy balance. Disruptions in this system can lead to sleep disorders and metabolic issues. Current treatments for narcolepsy target OX receptors, highlighting their importance.

Metabolic dysfunction-associated steatotic liver disease (MASLD) is strongly associated with increased subclinical atherosclerosis (measured by carotid intima-media thickness and coronary artery calcification) and incident cardiovascular events, but does not independently increase cardiovascular mortality risk after adjusting for confounders.

If you have MASLD, prioritize cardiovascular risk management (blood pressure, lipids, glucose) as aggressively as you manage your liver health. Your risk of heart events is elevated, but your risk of dying from liver failure is lower than dying from heart disease. Comprehensive cardiometabolic risk management is warranted.

Earlier age at menarche (specifically onset before 11 years) is associated with a significantly higher risk of developing type 2 diabetes and elevated cardiometabolic risk factors in adult women, independent of early-adulthood BMI.

For women who experienced early puberty (before age 11), there is a statistically higher baseline risk for type 2 diabetes and metabolic issues later in life, independent of their current weight. This does not mean diabetes is inevitable, but it suggests that metabolic monitoring (e.g., checking HbA1c, fasting glucose, and lipids) should be prioritized earlier and more frequently than for those with later menarche, starting in early adulthood.

High baseline and post-intervention levels of circulating microRNA-935 (c-miR-935) are associated with low weight loss response (<5% body mass loss) to a combined diet and exercise intervention, whereas high responders (>10% loss) exhibit lower levels.

If you are following a structured diet and exercise plan and seeing very little weight loss despite good adherence, your body's molecular response (specifically c-miR-935 levels) might be blunting your results. This doesn't mean the plan is wrong for you, but it may need adjustment. Consult a professional to see if biomarker testing or protocol modification (e.g., increasing the energy deficit or changing exercise type) is warranted.

Increases in circulating microRNA-221 (c-miR-221) and microRNA-223 (c-miR-223) abundance occur in both high and low responders to a combined diet and exercise intervention, suggesting these changes are driven by the exercise stimulus rather than the magnitude of weight loss.

Consistent exercise leads to beneficial molecular changes (increased c-miR-221 and -223) regardless of how much weight you lose. These changes are linked to improved energy metabolism and exercise adaptation. Focus on the consistency of the exercise stimulus for these health benefits, even if weight loss is slower than expected.

L-cells are not a homogeneous population; they are anatomically heterogeneous, with proximal (duodenal/jejunal) L-cells primarily secreting GLP-1 in response to macronutrients, while distal (ileal/colonic) L-cells co-secrete PYY and respond to microbial metabolites like SCFAs and bile acids.

Your gut's hormonal response to food depends on where the food is absorbed. Eating fiber and fats that reach the lower intestine (via fermentation or specific fats) stimulates different hormones (like PYY) than eating simple sugars in the upper intestine. A diverse diet that reaches different parts of the gut may optimize this hormonal signaling better than focusing on a single nutrient type.

Higher circulating concentrations of fatty acids produced via de novo lipogenesis (specifically 16:0, 16:1n7, and 18:0) are positively associated with an increased incidence of type 2 diabetes.

High levels of certain fats produced by your body (de novo lipogenesis) from carbs and alcohol are linked to a higher risk of type 2 diabetes. This suggests that managing carbohydrate and alcohol intake may help regulate these specific internal fat pathways, potentially lowering diabetes risk, independent of overall body weight.