Browse the evidence

Reduction or modification of dietary fat intake reduces combined cardiovascular events by 16% and cardiovascular mortality by 9%, but has no significant effect on total mortality.

To lower your risk of heart attacks and strokes, consider reducing your total fat and saturated fat intake, or replacing saturated fats with unsaturated fats. This change should be sustained for at least two years to see the full benefit, as short-term changes may not show significant results. While this won't necessarily extend your overall lifespan, it does reduce the risk of cardiovascular events.

The cardiovascular benefits of dietary fat reduction are only evident in trials with a mean follow-up duration of two years or longer.

If you are changing your fat intake to protect your heart, expect to maintain these changes for at least two years before seeing the full protective benefit. Short-term changes may not reduce your risk of cardiovascular events.

Both short (5-6 hours) and long (9-10 hours) sleep durations predict increased body weight and fat gain compared to average sleep (7-8 hours) over a 6-year period.

Aim for 7-8 hours of sleep per night. Both sleeping significantly less (5-6 hours) and significantly more (9-10 hours) is associated with greater weight and fat gain over time. Prioritize sleep consistency and duration as a key factor in weight management, independent of diet and exercise.

Low levels of sex hormone-binding globulin (SHBG) are associated with reduced insulin sensitivity in women with PCOS, independent of BMI, suggesting SHBG may serve as a useful clinical marker for insulin resistance in this population.

Low SHBG levels are a sign of insulin resistance in PCOS. While not a treatment target itself, monitoring SHBG can help assess metabolic health. Improving insulin sensitivity through lifestyle or medication often raises SHBG levels.

Weight loss interventions restore the normal secretion pattern of adipokines, reducing inflammatory markers and improving metabolic profiles.

Losing weight through diet is the most effective way to fix the hormonal imbalance caused by obesity. As you lose weight, your fat tissue stops pumping out inflammatory signals, which improves your insulin sensitivity and reduces cardiovascular risk.

Sleep loss and sleep disturbances activate the hypothalamo-pituitary-adrenal (HPA) axis, resulting in elevated evening cortisol levels and a shortened quiescent period.

Prioritize consistent sleep duration. Even modest sleep restriction (e.g., 4-6 hours) can elevate evening cortisol levels, which is linked to metabolic risks like obesity and diabetes. Protecting your sleep window is a direct way to manage stress hormones.

Slow-wave sleep (SWS) exerts an inhibitory effect on cortisol secretion, contributing to the quiescent period of the HPA axis.

Focus on getting deep, restorative sleep. SWS is crucial for suppressing cortisol during the night. Disruptions to deep sleep (e.g., by alcohol or sleep apnea) may prevent this natural cortisol drop.

DASH and Mediterranean diets reduce systemic inflammation (e.g., hs-CRP, cytokines), which indirectly attenuates neuroinflammation and neurodegeneration.

Focus on reducing systemic inflammation by following anti-inflammatory dietary patterns like DASH or Mediterranean. This helps protect the brain by lowering inflammatory markers like CRP and cytokines.

Waist circumference (WC) is a stronger predictor of type 2 diabetes risk than body mass index (BMI), and WC identifies cardiometabolic risk in individuals with normal BMI who would otherwise be missed by BMI-based screening.

Ask your doctor to measure your waist circumference. If you are a man, a measurement over 40 inches (102 cm) or a woman over 35 inches (88 cm) indicates higher risk for heart disease and diabetes, even if your weight (BMI) is normal. This measurement helps catch risks that standard weight checks miss.

Waist circumference is a valid surrogate marker for abdominal fat mass (both subcutaneous and intra-abdominal) and correlates strongly with cardiometabolic disease risk, though it does not distinguish between the two fat types.

Waist circumference is a reliable way to estimate abdominal fat, which is linked to heart and metabolic health. For consistent tracking, measure at the same spot (midpoint between ribs and hips) each time. It is more informative than weight alone for assessing metabolic risk.

Direct supplementation with Urolithin A (UA) improves skeletal muscle mitochondrial function and health span in elderly humans, bypassing the need for gut microbiome conversion of dietary precursors.

If you are over 60 and interested in supporting muscle health and mitochondrial function, direct Urolithin A supplementation is a viable option, especially if you do not naturally produce it from your diet. The first human trials show it is safe and improves muscle biomarkers. You do not need to rely on eating pomegranates or berries, as your gut may no longer convert them effectively.

Sleep problems are significantly associated with higher levels of psychological distress (anxiety and depression) across healthcare professionals, the general population, and COVID-19 patients.

If you are experiencing sleep problems during a high-stress period, recognize that this is strongly linked to increased anxiety and depression. Prioritizing sleep hygiene or seeking treatment for sleep issues is not just about rest; it is a critical step in mitigating psychological distress. Treating sleep problems may help reduce psychological distress, and vice versa.

The prevalence of sleep problems is highest among COVID-19 patients (57%), followed by healthcare professionals (31%), and the general population (18%).

Target sleep interventions should prioritize COVID-19 patients and healthcare workers, as they face the highest risk of sleep disruption. For the general public, sleep issues are less prevalent but still significant (1 in 5 people).

For endurance exercise lasting approximately 1 hour, rinsing the mouth with a carbohydrate solution and spitting it out improves performance, likely through oral carbohydrate sensing affecting brain motor output rather than metabolic fuel availability.

If you are competing in an event lasting about an hour, try rinsing your mouth with a sports drink for 5-10 seconds and spitting it out right before you start or during the race. This tricks your brain into thinking fuel is coming, which can help you push harder without actually consuming calories.

Short sleep duration (≤5 hours per night) and difficulties maintaining sleep are associated with a significantly increased incidence of type 2 diabetes in middle-aged men.

If you are a middle-aged man, prioritizing sleep is a critical diabetes prevention strategy, not just a wellness luxury. Specifically, aim for more than 5 hours of sleep and focus on sleep continuity (staying asleep). If you struggle with waking up frequently during the night, this is a specific metabolic risk factor that warrants attention, potentially through sleep hygiene or medical evaluation for sleep apnea, as it independently raises your diabetes risk.

Weight loss restores insulin sensitivity in obese women with PCOS to levels comparable to BMI-matched controls, but early insulin secretion remains persistently elevated.

For obese women with PCOS, significant weight loss (approx. 12-13 kg) can fully restore insulin sensitivity to that of a healthy, non-PCOS woman of the same weight. However, even after this success, the body may still over-secrete insulin early in response to glucose, suggesting that PCOS involves a persistent beta-cell or secretory abnormality independent of fat mass. Weight loss is critical for metabolic health, but may not fully correct all hormonal dysregulations in PCOS.

Time-restricted eating (TRE), defined as restricting daily caloric intake to a consistent 8–12 hour window, prevents and manages chronic metabolic diseases by aligning nutrient intake with circadian rhythms, independent of caloric restriction.

Restrict your daily food intake to an 8–12 hour window each day. For example, eat all your meals between 8 AM and 4 PM, or 10 AM and 6 PM. Try to keep this window consistent every day. You do not need to count calories or restrict the amount of food you eat, but aligning your eating with your body's natural clock helps regulate blood sugar and metabolism.

Weight reduction reverses supersaturated bile by significantly reducing hepatic cholesterol output, whereas caloric restriction alone (without weight loss) does not.

To fix supersaturated bile, you must lose weight, not just eat less. When you lose weight, your liver stops secreting so much cholesterol. If you just restrict calories without losing weight, your body pulls cholesterol from fat stores, keeping your bile saturated.

Dietary composition (specifically carbohydrate vs. animal fat/protein intake) shapes gut microbiota enterotypes (Prevotella vs. Bacteroides dominance), which in turn influences host health outcomes including inflammation, metabolic disease risk, and immune function via microbial metabolite production.

Focus on the quality and type of carbohydrates and fats in your diet, as these directly shape your gut bacteria. A diet high in fiber/carbs may favor Prevotella, while high animal fat/protein may favor Bacteroides. These shifts affect your inflammation and metabolic health. Personalized nutrition based on your microbiome may be more effective than universal dietary guidelines.

Higher hepatic fat content, estimated by the Fatty Liver Index (FLI > 60), is independently associated with increased insulin resistance, higher coronary heart disease (CHD) risk, and early carotid atherosclerosis (increased intima media thickness) in middle-aged, nondiabetic adults.

If you are generally healthy but have a high Fatty Liver Index (calculated via waist, BMI, triglycerides, and liver enzymes), you likely have underlying insulin resistance and early signs of arterial thickening, even if your blood sugar and blood pressure are normal. Addressing liver fat through lifestyle changes can mitigate these hidden cardiovascular risks.

An increase in the proportion of ultraprocessed foods in the diet is associated with a higher risk of all-cause mortality in middle-aged adults.

To lower your risk of early death, try to reduce the percentage of your diet that comes from ultraprocessed foods (like packaged snacks, sugary drinks, and ready meals). Even a small reduction in these items can have a measurable positive impact on your longevity.

Replacing sucrose with polyols (such as erythritol, xylitol, or maltitol) significantly lowers the Glycemic Index (GI) and Insulinaemic Index (II) of foods, leading to improved long-term glycemic control (lower HbA1c) in type 2 diabetes patients without requiring large caloric deficits.

To improve blood sugar control, swap high-GI sugars (like sucrose) with polyols (like erythritol, xylitol, or maltitol) in your diet. You do not need to consume large amounts; even small daily substitutions (15-20g) can improve long-term glycemic markers like HbA1c. Be mindful of digestive tolerance, but the amounts needed for metabolic benefit are typically well-tolerated.

Administration of low-dose leptin reverses the adaptive reduction in energy expenditure and the decline in circulating thyroid hormones that occur as physiological responses to sustained weight loss.

If you have lost weight and feel your metabolism has slowed down permanently, this research suggests that your body's hormone levels (specifically leptin and thyroid hormones) may be driving this slowdown. While this specific study uses leptin injections, it highlights that metabolic slowdown after weight loss is a reversible hormonal state, not necessarily a permanent 'broken' metabolism. Consult a doctor about hormonal evaluations if you are struggling with metabolic adaptation post-weight loss.

Rotating night shift work (RNS) significantly increases the risk of chronic fatigue, sleep disorders, and cardiovascular symptoms compared to day shift work.

If you work rotating night shifts, your body is fighting its natural clock, leading to higher risks of heart issues, poor sleep, and exhaustion. This isn't just 'being tired'; it's a physiological stressor. Prioritize sleep hygiene aggressively on days off, and advocate for schedule designs that allow for adequate rest (e.g., at least 11 hours between shifts) and clockwise rotation, which are less disruptive to your circadian rhythm.