Browse the evidence

Daytime exposure to bright light, particularly blue wavelengths, is beneficial for circadian entrainment and health, whereas nighttime exposure is disruptive.

Seek bright, blue-rich light during the day to strengthen your circadian rhythm. Avoid bright, blue-rich light at night to protect your sleep and hormonal balance.

Melatonin supplementation is effective in preventing or reducing jet lag symptoms without meaningful side effects.

If you are traveling across multiple time zones, consider using melatonin supplements to help reduce jet lag symptoms. It is widely used and has no known meaningful side effects.

Roux-en-Y gastric bypass (RYGB) provides superior long-term type 2 diabetes (T2DM) remission, lower relapse rates, and better glycemic control compared to sleeve gastrectomy (SG) in real-world clinical settings.

If you have Type 2 Diabetes and are considering bariatric surgery, Roux-en-Y Gastric Bypass (RYGB) is associated with better long-term diabetes remission and lower relapse rates compared to Sleeve Gastrectomy (SG). While SG is a common procedure, RYGB may offer superior metabolic benefits for diabetes management, though it involves a more complex surgery. Discuss these long-term outcomes with your surgeon to make an informed choice.

Large-scale food fortification and biofortification are highly cost-effective public health interventions that significantly reduce micronutrient deficiencies (anemia, vitamin A deficiency, iodine deficiency) and associated health burdens in low- and middle-income countries.

For public health policymakers in LMIC: Implement mandatory fortification of staple foods (wheat, maize, rice, salt, sugar, oil) with essential micronutrients (iron, iodine, vitamin A, folic acid). Ensure strong government enforcement, quality control, and monitoring to guarantee compliance. This is one of the most cost-effective ways to improve population health, reduce anemia, prevent birth defects, and boost economic productivity.

Vitamin D3 supplementation at 100 mcg (4000 IU)/day is safe for long-term use in adults, as it does not elevate plasma calcium levels.

Taking 4000 IU of Vitamin D3 daily is safe and does not raise calcium levels, even over long periods.

Smoking is associated with lower cardiorespiratory fitness and respiratory function, and smoking cessation is associated with better maintenance of these functions over time.

Quitting smoking improves cardiorespiratory fitness over time, even if you were a smoker previously. Never smoking is associated with the best maintenance of fitness.

Low energy availability (EA <30 kcal/kg FFM/day) causes functional hypothalamic amenorrhea (FHA) in female athletes through suppressed GnRH pulsatility, leading to decreased estradiol and progesterone.

If you are a female athlete experiencing missed periods, check your energy intake relative to your exercise expenditure. If your energy availability is consistently below 30 kcal per kg of fat-free mass per day, you are at high risk for hormonal suppression. Consult a specialist to address this before bone health is compromised.

Low energy availability reduces resting metabolic rate (RMR) by approximately 8% as an energy-conserving mechanism, independent of changes in body composition.

If you are training heavily and eating very little, your body may slow down its baseline calorie burn to survive. This is a normal adaptation, not a broken metabolism. Restoring adequate energy intake will help normalize your metabolic rate.

Low energy availability suppresses leptin levels and elevates ghrelin and peptide YY (PYY), disrupting appetite regulation and contributing to the maintenance of low energy states.

Low energy intake changes your hunger hormones: leptin drops, ghrelin and PYY rise. This can make it harder to feel hunger cues accurately and may contribute to disordered eating patterns. Prioritize regular, adequate meals to normalize these hormones.

Low energy availability leads to decreased IGF-1 and increased GH, indicating GH resistance at the liver, which impairs bone and muscle anabolism.

If you are under-fueled, your body may produce more GH but fail to use it effectively (GH resistance), leading to low IGF-1. This impairs bone and muscle health. Restoring energy intake can help normalize this axis.

Baseline malnutrition, diagnosed via GLIM or ESPEN criteria, is a strong predictor of developing sarcopenia or severe sarcopenia within four years in community-dwelling older adults.

If you are an older adult, your nutritional status is a key predictor of whether you will lose muscle mass. Being malnourished (defined by criteria like low BMI, weight loss, or low muscle mass) increases your risk of developing sarcopenia by 3-4 times over four years. Focus on maintaining adequate nutrition, including protein intake, as a primary strategy to prevent muscle loss, rather than viewing muscle loss as inevitable.

Pharmacological doses of isolated viscous soluble fiber (e.g., guar gum) improve insulin sensitivity, reduce LDL-cholesterol, and lower clotting factors, whereas isolated insoluble cereal fiber (e.g., wheat bran) does not directly act on these risk factors when consumed in refined forms.

To improve insulin sensitivity and lower LDL cholesterol, focus on viscous soluble fiber sources like oats, barley, or supplements like guar gum, taken in significant amounts (e.g., 10g+ per dose). Simply eating 'high fiber' refined grains (like white flour with added bran) may not provide these specific metabolic benefits.

Low glycaemic index (GI) diets and lente carbohydrate foods reduce the risk of type 2 diabetes and cardiovascular disease, potentially through mechanisms involving reduced insulin demand, improved HDL levels, and reduced clotting factors (PAI-1), independent of or in addition to fiber effects.

Choose minimally refined grains and whole foods that have a low glycaemic index. This approach reduces the risk of type 2 diabetes and heart disease, especially if you are overweight or have a family history of these conditions. The benefit comes from slower carbohydrate release, which lowers insulin demand and improves lipid profiles.

Higher BMI categories (overweight and obesity classes I-III) are significantly associated with impaired health-related quality of life (HRQL), including worse general health status and more unhealthy days, mediated by joint pain and obesity-related comorbidities.

Maintaining a healthy weight is crucial for your daily quality of life. Higher BMI is linked to more pain, chronic conditions, and fewer healthy days. Focus on sustainable lifestyle changes to manage weight and reduce these risks.

Selenium deficiency alters gut microbiota composition and function, leading to a phenotype that increases susceptibility to cancer, thyroid dysfunction, inflammatory bowel disease, and cardiovascular disorders.

Ensure adequate selenium intake through diet (e.g., Brazil nuts, seafood, meat) or supplementation if deficient, as this supports a healthy gut microbiota which protects against chronic diseases like cancer and cardiovascular disorders.

In conditions of limited selenium supply, intestinal bacteria compete with the host for selenium, reducing host selenoprotein levels by two to three times.

If you have low selenium levels, be aware that your gut bacteria may compete for it. Ensuring adequate selenium intake through diet or supplementation can help maintain your own selenoprotein levels.

High-dose selenium supplementation (200 µg/day) as selenized yeast or L-selenomethionine has shown mixed results in cancer prevention trials, with some showing reduced risk and others showing no benefit or increased risk.

Selenium supplementation (200 µg/day) has shown mixed results in cancer prevention. It may be beneficial in some populations (e.g., those with low baseline selenium) but not others. Consult a healthcare provider for personalized advice.

Women with polycystic ovary syndrome (PCOS) exhibit a distinct metabolic profile characterized by elevated lactate, long-chain fatty acids, and specific amino acids (valine, leucine, serine, threonine, phenylalanine, tyrosine, ornithine), alongside reduced glucose, glycine, and proline, which serves as a biomarker for insulin resistance and diabetes risk.

If you have PCOS, your body's metabolism is fundamentally different, affecting how you process sugars, fats, and proteins. This isn't just about weight; it's about your risk for diabetes and heart disease. Key markers like low glycine and high valine/leucine can help doctors assess your risk. Managing insulin resistance through diet and exercise is crucial, as it addresses the root metabolic dysfunction, not just the symptoms.

Weight cycling (repeated weight loss and regain) is associated with a 1.25 to 2.00 relative risk increase in all-cause mortality and coronary heart disease (CHD) mortality compared to stable weight.

If you have experienced weight cycling, do not stop trying to lose weight. The mortality risk associated with weight cycling (1.25-2.00x) is similar to the risk of obesity itself. Focus on maintaining weight loss and improving health markers rather than fearing the natural fluctuations that occur during dieting.

Thirty-eight days of endurance exercise training significantly attenuates leucine oxidation and branched-chain 2-oxoacid dehydrogenase (BCOAD) activation during moderate-intensity exercise in humans.

If you start an endurance training program, your body becomes more efficient at sparing protein (leucine) during exercise. You do not need to increase your protein intake just because you are exercising more, as long as your intensity is moderate (around 60% VO2 peak). The body adapts by reducing the breakdown of amino acids for energy.

Females oxidize proportionately more lipid and less carbohydrate and protein (leucine) than males during moderate-intensity endurance exercise.

Women tend to burn more fat and spare more protein than men during moderate cardio. This is a natural metabolic adaptation. You do not need to force high protein intake or high carb intake specifically for cardio recovery if you are exercising at moderate intensities.

Fat oxidation during aerobic exercise is maximized at moderate intensities (approximately 60-65% VO2max) and decreases significantly at higher intensities (>75% VO2max) due to the Randle cycle and reduced plasma fatty acid availability.

To maximize the rate of fat oxidation, exercise at a moderate intensity, roughly 60-65% of your maximum oxygen uptake (VO2max). This is often described as a 'conversational pace.' Pushing into high-intensity zones shifts your body to burn more carbohydrates and less fat, even if you burn more total calories.

Endurance training increases maximal fat oxidation (MFO) and shifts the intensity at which MFO occurs to higher workloads, primarily through increased intramuscular triglyceride (IMTG) utilization and mitochondrial density.

If you train for endurance, your body becomes more efficient at burning fat. This is due to increased mitochondrial density and greater storage of fat within muscles (IMTG). This adaptation allows you to burn more fat at higher intensities than an untrained person.

Dietary fiber is a more reliable predictor of satiety and metabolic health than Glycemic Index, as low-GI diets often derive their benefits from higher fiber content rather than the glycemic response itself.

Prioritize fiber over Glycemic Index. If you are choosing between carbohydrate sources, pick the one with more fiber (vegetables, legumes, whole grains) rather than worrying about whether it spikes blood sugar quickly. High-fiber foods naturally promote fullness and better metabolic markers, making the GI calculation unnecessary for most people.