Browse the evidence

Dietary interventions produce observable changes in gut microbiome composition within days, whereas microbiome-mediated effects on host phenotypes or biomarkers require interventions lasting weeks to months.

If you change your diet, your gut bacteria will likely adapt within a few days. However, do not expect to feel health benefits or see changes in blood markers immediately. You need to maintain the dietary change for several weeks or months to see the downstream health effects driven by those microbial changes.

Microbiome responses to dietary interventions are highly personalized, meaning the same diet can produce different microbial and metabolic outcomes in different individuals based on their baseline microbiome composition.

Standard dietary advice may not work for everyone because your gut bacteria are unique. If a specific diet (like high fiber) doesn't improve your health markers, it might be due to your baseline microbiome. Future personalized nutrition may involve testing your microbiome to predict which foods will work for you.

Ultra-processed foods contribute disproportionately to daily energy intake in high-income countries, often exceeding 50% of total calories.

Be aware that in many high-income countries, more than half of the calories consumed come from ultra-processed foods. Reducing this proportion is a key public health goal.

Suboptimal intake of specific dietary factors (nuts/seeds, seafood omega-3, processed meats, whole grains, vegetables, fruits, SSBs, sodium, red meat, polyunsaturated fats) accounts for 18.2% of total cardiometabolic disease costs in the US, totaling $50.4 billion annually.

Focus on increasing intake of nuts, seeds, and seafood omega-3s, and reducing processed meats, sodium, and sugar-sweetened beverages. These changes have the highest potential to reduce cardiometabolic disease risk and associated healthcare costs.

Training with low muscle glycogen availability augments the activation of signaling proteins and the resulting phenotypic adaptations for mitochondrial biogenesis compared to training with normal glycogen.

If you want to maximize mitochondrial growth, you can try training with lower muscle glycogen. This might mean doing your workout before eating a large carb-heavy meal, or doing a second session later in the day when glycogen is depleted. This state of 'low fuel' signals your body to build more mitochondria more aggressively than when you are fully fueled. However, this may reduce your performance output during the workout itself.

Adherence to a Mediterranean diet prevents long-term weight gain and abdominal obesity in individuals who are normal weight at baseline, but does not reverse existing overweight or obesity.

If you are currently a healthy weight, adopting a Mediterranean diet pattern is a strong strategy to prevent future weight gain and belly fat accumulation. However, if you are currently overweight or obese, this diet pattern alone is unlikely to result in significant weight loss or BMI normalization; you likely need to combine it with other interventions like caloric restriction or increased physical activity.

A dietary pattern characterized by high intake of sugar-sweetened beverages, fruit juice, and table sugar/preserves (but low in butter/high-fat cheese) is associated with increased risk of CVD and all-cause mortality, particularly in the highest consumption quintile, potentially independent of BMI and traditional risk factors.

Limit your intake of sugar-sweetened beverages, fruit juice, and table sugar/preserves. Even if you keep your saturated fat intake low, high consumption of these sugary items is linked to a higher risk of heart disease and early death, especially if you are in the highest consumption group. Choose water, unsweetened tea, or whole fruits instead.

A ketogenic diet significantly downregulates microbial amino acid and vitamin biosynthesis pathways compared to a vegan diet, likely due to higher dietary availability of these nutrients reducing host reliance on microbiome-derived metabolites.

On a ketogenic diet, your gut bacteria produce fewer amino acids and vitamins because you are getting them directly from food. This suggests that the microbiome's role shifts based on dietary intake, and you may not need to rely on gut bacteria for these nutrients as much as on a vegan diet.

Resistance training protocols must report within-exercise variables beyond load and repetitions—including failure status, range of motion, time under tension, and attentional focus—to accurately determine the training stimulus.

When designing or documenting a resistance training program, do not just list the weight and number of reps. You must also specify whether sets were taken to failure, the range of motion used (full or partial), the speed/tempo of each phase, and whether the athlete used an internal or external focus. This level of detail is required to replicate the stimulus and ensure the training is effective.

Training to failure produces greater hypertrophic adaptations than training not to failure, but only when total volume is not equated; when volume is equated, the two methods yield equivalent results.

You do not need to train to failure on every set to maximize muscle growth. If you train close to failure but stop before, you can achieve similar hypertrophy as long as you match the total volume (sets x reps x load) of a failure-based program. Training to failure increases recovery time and may not be comfortable for beginners.

Obesity contributes to metabolic derangements, poorer lung and kidney function, vascular health issues, low-grade inflammation, and thrombotic potential, which collectively reduce the body's capacity to cope with the systemic effects of the hyperimmune response in COVID-19.

Obesity affects multiple body systems, making it harder to fight off severe infections like COVID-19. Managing weight can help improve these underlying health issues, potentially reducing the risk of severe illness. Focus on sustainable lifestyle changes to improve overall health.

Implementing the US FDA's voluntary sodium reformulation targets for processed foods reduces population sodium intake, lowers systolic blood pressure, and significantly decreases cardiovascular disease incidence and mortality, resulting in substantial net cost savings for society.

Supporting the FDA's voluntary sodium reduction goals for processed foods is a highly effective public health strategy. Even if compliance is not 100%, reducing sodium intake in processed foods lowers blood pressure and prevents hundreds of thousands of cardiovascular events, saving billions in healthcare costs. Focus on choosing lower-sodium processed options and advocating for industry reformulation.

Polygenic risk scores (PRS) derived from South Asian-specific genetic data provide significantly better prediction of Type 2 Diabetes (T2D) risk than PRS derived from European data, identifying individuals with ~4-fold higher risk in the top quartile.

If you are of South Asian descent, standard genetic risk models based on European data may underestimate your specific risk for Type 2 Diabetes. To get an accurate assessment, seek out or advocate for polygenic risk scores (PRS) that are specifically calibrated using South Asian genetic data. This can identify if you are in the top quartile of genetic risk, which correlates with a 4-fold higher likelihood of developing T2D compared to the bottom quartile. Knowing this allows for earlier, more aggressive lifestyle interventions (diet, exercise, regular screening) to mitigate that risk.

In patients with new-onset type 2 diabetes, weight change (gain or loss) of more than 10% is associated with higher all-cause mortality compared to stable weight.

If you have recently been diagnosed with type 2 diabetes, aim to maintain your weight. Both losing more than 10% and gaining more than 10% of your body weight in the first two years are associated with higher mortality. Stable weight is linked to the lowest risk of death.

Combining waist circumference (WC) and relative handgrip strength (HGS/BW) provides a significantly more accurate prediction of metabolic syndrome (MetS) risk than using either metric alone.

To better assess your risk for metabolic syndrome, do not rely on waist size or muscle strength alone. Measure your waist circumference and test your handgrip strength (normalized to your body weight). Combining these two simple, low-cost measurements provides a significantly more accurate risk profile than using either metric by itself.

Resistance training performed to momentary muscular failure does not produce superior muscle hypertrophy compared to non-failure training.

You do not need to train to momentary muscular failure to maximize muscle growth. Training with 1-3 reps in reserve (RIR) is likely sufficient for hypertrophy. This allows you to recover faster and perform more total work over time, which may be more beneficial than chasing failure on every set.

Higher velocity loss thresholds (>25%) do not produce superior muscle hypertrophy compared to moderate velocity loss (20-25%).

For resistance-trained individuals, stopping sets at moderate velocity loss (20-25%) is just as effective for muscle growth as stopping at high velocity loss (>25%). You can simplify your training by not obsessing over precise velocity loss metrics.

Resistance training performed to 'set failure' (defined as anything other than momentary muscular failure) provides a trivial advantage over non-failure training for muscle hypertrophy.

Training to 'set failure' (broadly defined) offers a trivial advantage over non-failure training. The practical benefit is minimal, so you can choose your failure definition based on comfort and recovery rather than expecting significant hypertrophy gains.

Men experience significantly greater weight loss, fat mass loss, and lean mass loss on a healthy low-carbohydrate (HLC) diet compared to a healthy low-fat (HLF) diet, whereas women achieve similar weight loss outcomes on both diets.

If you are a man, a healthy low-carbohydrate diet is likely to produce greater weight loss than a healthy low-fat diet. If you are a woman, both diets are equally effective for weight loss, so you should choose the one you can adhere to best. Men lose more weight and fat on HLC, while women lose similar amounts on either diet.

Higher-quality protein sources lead to greater strength gains during resistance exercise training, but do not significantly increase lean body mass (LBM) compared to lower-quality proteins.

When doing resistance training, choosing high-quality protein (like whey or meat) may help you get stronger, but it won't necessarily make you bigger than if you ate lower-quality protein (like soy or wheat), as long as you eat enough total protein. Don't overspend on 'premium' protein if your total intake is adequate.

South Asian ethnicity is associated with a significantly higher risk of developing Type 2 Diabetes (T2D) and insulin resistance compared to White populations, driven by distinct metabolic signatures including elevated branched-chain amino acids (BCAAs) and altered lipid metabolism.

If you are of South Asian descent, your risk for Type 2 Diabetes is statistically higher than that of White populations, often manifesting at lower BMIs. This is linked to how your body metabolizes amino acids and fats. Focus on monitoring metabolic markers like fasting glucose and insulin sensitivity, and consider dietary patterns that manage carbohydrate intake and support healthy lipid metabolism, as personalized strategies based on these metabolic insights are more effective than generic advice.

Roux-en-Y gastric bypass (RYGB) surgery is the most cost-effective intervention for adults with severe obesity (BMI ≥ 35 kg/m2) compared to non-surgical weight management programs, primarily due to superior long-term weight loss and reduced incidence of obesity-related diseases.

For individuals with severe obesity (BMI ≥ 35), bariatric surgery (specifically RYGB) offers the best long-term health and economic value compared to diet and lifestyle programs alone. While surgery has high upfront costs and requires lifelong medical follow-up, it significantly reduces the risk of serious diseases like diabetes and heart disease, leading to more quality-adjusted life years. If surgery is not an option, a standard 12-week behavioral weight management program is the next most cost-effective choice, but adding very low-calorie diets to standard programs is not cost-effective.

Performing resistance training before high-intensity interval training (RT+HIIT) in same-day concurrent sessions attenuates lower-body power development (countermovement jump displacement, force, and power) compared to resistance-only training, whereas aerobic fitness and strength gains remain comparable.

If you train resistance and cardio on the same day and care about explosive power (like jumping or sprinting), do your weights first. Doing cardio first will blunt your power gains, even if your strength and endurance improve normally. Keep the gap between sessions to at least 3 hours if possible.

Performing high-intensity interval training (HIIT) before resistance training (HIIT+RT) does not attenuate lower-body maximal strength or lean mass gains compared to resistance-only training, making it a viable strategy for concurrent training.

If you must do cardio and weights on the same day, doing cardio first won't hurt your strength or muscle growth, provided you wait about 3 hours between sessions. You can still get strong and build muscle.