Browse the evidence

Increasing sleep duration by approximately one hour per night is associated with a statistically significant reduction in population-level Body Mass Index (BMI), suggesting a public health benefit for obesity prevention despite unproven individual causality.

If you are a short sleeper, try to get an extra hour of sleep each night. You likely won't lose a significant amount of weight yourself, but this small shift contributes to better population health and reduces your risk of obesity. The cost is minimal (just waking up slightly less), and the benefit is a lower average BMI for society.

Government-imposed pandemic containment strategies, including lockdowns and social distancing, cause a significant decline in physical activity across all age groups and genders.

Pandemic restrictions significantly reduce physical activity for most people, regardless of age or gender. To mitigate this, seek out alternative forms of exercise like digital training or home workouts, as maintaining activity is crucial for preventing negative health outcomes during lockdowns.

Off-farm income is a critical mechanism for smoothing food consumption and maintaining dietary diversity during the lean season.

Diversify your income sources. Do not rely solely on farm sales. Engage in off-farm activities (wage labor, small business) to generate cash for buying food, especially during the lean season when your own production is depleted.

There is no dose-response relationship for liver enzyme improvement beyond 60 minutes/week of increased physical activity in NAFLD patients.

You don't need to exercise excessively to improve your liver enzymes. Increasing your activity by just 60 minutes per week (e.g., 10 minutes a day) is enough to see significant benefits. Going beyond this threshold does not provide additional liver enzyme improvements, though it may help with weight loss.

Physical activity improves insulin sensitivity by altering skeletal muscle fatty acid composition, specifically by reducing palmitic acid and improving delta-5 desaturase activity.

Regular physical activity changes the fat composition in your muscles, lowering palmitic acid and improving enzyme activity related to insulin sensitivity, even if your diet stays the same.

Low socioeconomic status, blue-collar occupation, female gender, and poor perceived health are significant predictors of physical inactivity in adulthood.

Recognize that socioeconomic barriers (cost, time, transport) significantly impact activity levels. For those with lower income or blue-collar jobs, prioritize accessible, low-cost activities and address perceived health barriers early.

Earlier physical activity, particularly competitive or recreational sport participation, is a key determinant of maintaining physical activity and reducing healthcare needs in old age.

Maintain physical activity from youth into old age. Early sport participation predicts better health outcomes and reduced hospital care in late life. For older adults, leveraging past active identities can help maintain activity.

U.S. adults are reporting significantly shorter sleep durations (≤6 hours) with a statistically significant increasing trend beginning in 2013, disproportionately affecting Black and Hispanic populations.

If you are an adult in the U.S., you are likely sleeping less than you think, specifically if you are Black or Hispanic. The data shows a sharp rise in short sleep (under 6 hours) starting in 2013. To counter this, you must actively manage environmental factors: limit smartphone use before bed and address sources of economic or social stress, as these are the primary drivers of the observed trend.

Digital Cognitive-Behavioral Therapy for Insomnia (dCBT-I) is a cost-effective and viable method for delivering CBT-I at scale, potentially reducing healthcare expenditures.

If you cannot access a therapist for CBT-I, look for validated digital CBT-I programs. They are increasingly recognized as cost-effective and can provide the same core therapeutic benefits.

Physical activity is inversely associated with insulin resistance and circulating metabolite levels, but these associations are largely attenuated when adjusting for HOMA-IR, suggesting physical activity improves insulin sensitivity directly rather than by lowering specific metabolite levels.

Exercise improves insulin sensitivity directly. While your blood tests might show changes in amino acids after exercising, these changes are likely just a reflection of your improved metabolic health, not the primary mechanism. Don't worry if your amino acid levels don't drop perfectly; focus on the consistency of your physical activity.

Implementing specific health taxes on sugar-sweetened beverages at rates of 20% or higher significantly reduces consumption and improves population health outcomes, whereas lower rates (<20%) generally fail to produce meaningful behavioral change.

To effectively reduce sugar-sweetened beverage consumption, policymakers must implement specific taxes that raise the shelf price by at least 20%. Lower taxes (under 20%) are ineffective because consumers do not react to small price increases, especially if the tax is not clearly visible on the shelf. To mitigate political backlash regarding the regressive nature of these taxes, revenues should be earmarked for health-related spending or subsidies for healthy foods.

Previous race experience, specifically the number of ultra-marathon finishes and personal best marathon time, is the most important predictor of successful ultra-marathon performance.

If you are new to ultra-running, prioritize completing shorter ultra-distances to gain experience. Your personal best marathon time and the number of ultras you have finished are better predictors of your future success than your current fitness level alone. Start with shorter ultras to build this specific experience.

Adding social influence strategies (monetary incentives, peer support) to maintenance programs improves adherence to weight loss strategies, though it does not necessarily lead to greater weight loss compared to therapist contact alone.

Using external rewards like group challenges or small incentives can help you stick to your plan in the short term. However, rely on these as a bridge to build habits, not the end goal. If you stop getting rewards, your adherence might drop. Focus on building problem-solving skills with a coach or support group to handle obstacles without needing external prizes.

Postponing the onset of chronic disease and disability through lifestyle interventions (primordial, primary, secondary, and tertiary prevention) compresses the period of morbidity, reducing lifetime disability and healthcare costs without necessarily extending maximum life expectancy.

To compress your morbidity, focus on preventing risk factors (primordial prevention) and reducing existing ones (primary/secondary prevention). This means avoiding smoking, maintaining a healthy weight, exercising regularly, and managing conditions like hypertension. These actions delay the onset of disability more than they extend your maximum lifespan, resulting in fewer years of suffering and lower healthcare costs. It is not inevitable; it requires active lifestyle management.

Exposure to environmental food cues (visual, olfactory, marketing) can trigger conditioned food intake and override homeostatic satiety signals, leading to overconsumption even when metabolically replete.

Your environment drives your eating more than your hunger. If you are exposed to constant food cues (ads, availability), your brain will trigger eating even when full. To manage this, you must minimize exposure to these cues (e.g., unsubscribe from food marketing, keep healthy foods visible and junk food hidden) because willpower alone is insufficient against conditioned responses.

Environmental interventions that reduce the availability or increase the price of sugar-sweetened beverages (SSBs) significantly decrease SSB consumption and sales.

To reduce sugar-sweetened beverage intake, change the environment rather than relying on willpower. Make healthy drinks (water, diet) the default and easy to find, while making SSBs harder to find or more expensive. This works for individuals (home delivery of water) and communities (school policies, store promotions).

Moderate to moderately vigorous physical activity significantly reduces the risk of heart attacks in middle-aged men without pre-existing ischaemic heart disease, whereas vigorous activity may increase this risk.

For heart health, aim for moderate to moderately vigorous activity, such as brisk walking, cycling, or frequent recreational tasks. You do not need to engage in strenuous sports to gain significant protection against heart attacks. In fact, sticking to moderate levels may be safer and more effective than pushing into vigorous exertion, which was associated with higher risk in this group.

Implementing mandatory front-of-package warning labels on foods high in critical nutrients (sugar, saturated fat, sodium, energy) reduces consumer intention to buy unhealthy products.

For policymakers and public health advocates: Use simple, high-contrast warning labels (like a black octagon) on food packaging. Ensure the label is large (at least 10% of the front package) and clearly states 'Excess of [Nutrient]'. Pair this with public education to prevent misinterpretation, especially among low-SES groups and adolescents, as some may misread warnings as recommendations.

Regulatory bans or restrictions on unhealthy foods (e.g., trans fat bans, SSB bans) and mandates for healthier options in institutional settings (schools) significantly improve dietary quality and reduce consumption of target nutrients, whereas menu labeling alone has negligible impact on purchasing behavior.

If you are a policymaker or business owner, implement bans on trans fats and restrictions on sugary drinks in vending/schools. Do not rely on menu labeling alone, as evidence shows it fails to change purchasing behavior.

Built environment interventions that improve active transportation infrastructure (bike lanes, trails, light rail) increase process outcomes (cycling rates, walking volume) but do not consistently increase total physical activity or reduce BMI.

Invest in bike lanes and trails to increase cycling and walking for transport, but do not expect this to significantly lower BMI or obesity rates on its own. Combine with dietary interventions for weight management.

A personal invitation from a health practitioner significantly increases the likelihood of an older adult accepting a falls-prevention intervention.

Healthcare providers should personally invite older patients to strength and balance programs rather than relying on general referrals or flyers.

Group-based falls-prevention interventions are unsuitable for a significant subset of older adults due to social discomfort, physical challenges, or practical barriers.

Provide home-based exercise options as an alternative to group classes for older adults who find groups intimidating, physically challenging, or logistically difficult.

Intensive lifestyle interventions produce significantly attenuated weight loss in Black women compared to White and Hispanic men and women, as well as Black men.

If you are a Black woman participating in a lifestyle weight loss program, expect your weight loss to be slower and smaller than your White or Hispanic peers, even with full adherence. This is likely due to external sociocultural and environmental barriers, not a lack of effort. Seek programs that offer cultural tailoring and flexible delivery methods to overcome these specific challenges.

Implementing an intuitive eating approach (eating when hungry, stopping when full, no food restrictions) results in weight maintenance rather than significant weight loss in overweight/obese individuals, while significantly improving psychological health indicators.

Focus on eating when you are physically hungry and stopping when you are comfortably full, without labeling foods as 'good' or 'bad'. This approach is unlikely to result in significant weight loss or increased physical activity, but it may help maintain your current weight and significantly improve your psychological well-being, body image, and relationship with food. It requires practice to distinguish true hunger from emotional or environmental cues.