Browse the evidence

Calorie or protein restriction slows aging and reduces cancer rates in rodents by enhancing maintenance functions, including DNA repair and antioxidant defenses, thereby reducing oxidative damage.

While direct long-term human trials are lacking, evidence from rodents suggests that moderate calorie or protein restriction may slow aging and reduce cancer risk by improving the body's ability to repair DNA and fight oxidative stress. This should be done carefully and ideally under guidance.

Associations between specific nutrient intakes and disease are likely secondary to differences in total caloric intake, body size, physical activity, or metabolic efficiency, rather than representing primary etiologic effects of the nutrient itself.

When evaluating diet-disease links, do not trust absolute nutrient numbers (like grams of fat) or simple percentages (nutrient density) if total calories vary between groups. Instead, use statistical methods (like regression residuals) to isolate the nutrient's effect independent of total energy intake. If a nutrient's association with disease disappears after adjusting for calories, the nutrient itself is likely not the primary cause.

In individuals with type 2 diabetes and obesity, skeletal muscle mitochondria exhibit reduced functional capacity (Complex I activity) and smaller morphological size, which correlates with the severity of insulin resistance.

If you have type 2 diabetes or obesity, your muscle mitochondria may be less efficient at burning fuel, contributing to insulin resistance. This is not just a 'willpower' issue but a biological one. However, because this dysfunction correlates with insulin resistance, interventions that improve metabolic health (like exercise, which increases mitochondrial biogenesis) can potentially reverse or mitigate these structural and functional deficits.

Butyrate maintains anaerobic conditions in the colon by activating PPARγ and repressing inducible nitric oxide synthase (iNOS), which prevents the proliferation of pathogenic facultative anaerobes like Enterobacteriaceae.

Maintain a healthy gut barrier by ensuring adequate butyrate production. Butyrate, a short-chain fatty acid produced by bacteria from fiber, activates PPARγ in colon cells to limit oxygen diffusion and repress inflammatory enzymes (iNOS). This creates an anaerobic environment that suppresses pathogenic bacteria like Enterobacteriaceae. Prioritize dietary fibers that promote butyrate production, such as resistant starches.

Current trends in the U.S. population project that by 2030, nearly 1 in 2 adults will have obesity (BMI ≥30) and nearly 1 in 4 will have severe obesity (BMI ≥35), with severe obesity becoming the most common BMI category among women, non-Hispanic black adults, and low-income adults.

This paper does not offer an individual intervention but highlights a massive public health trend. For an individual, the key takeaway is that the environment is becoming increasingly obesogenic, particularly for low-income and minority groups. Prevention efforts at the community and policy level are critical to counteracting these projected trends.

For a given waist circumference, a higher BMI is associated with lower mortality risk, likely due to greater protective subcutaneous fat storage in the lower body.

If you have a large waist, having a higher BMI might be less risky than having a low BMI with the same large waist. This is because lower-body fat may protect your organs from harmful visceral fat.

A secular decline in occupation-related physical activity (reducing daily energy expenditure by >100 kcal) has significantly contributed to the increase in mean U.S. body weight over the last 50 years.

Your job is likely costing you weight control. Since 1960, U.S. jobs have become significantly less physically demanding, burning over 100 fewer calories per day on average. To maintain your weight, you must consciously incorporate physical activity outside of work that matches this deficit (e.g., 150 minutes of moderate activity per week), as your workplace is no longer doing it for you.

Obesity is primarily driven by an obesogenic environment characterized by increased availability of low-cost, energy-dense foods and reduced physical activity, rather than solely by individual lack of self-control.

Focus on modifying your environment to support healthy choices. This means prioritizing access to fresh foods, reducing exposure to marketing of energy-dense processed foods, and integrating physical activity into your daily routine (e.g., walking, biking) rather than relying solely on willpower or extreme dieting. Advocate for community-level changes like safer sidewalks and healthier food options.

Leptin-replacement therapy reduces daily caloric intake and resting metabolic rate in patients with lipodystrophy.

Leptin therapy naturally reduces hunger and metabolic rate in these patients, contributing to weight loss and metabolic improvement.

AMPK activation prevents cancer initiation and promotion by suppressing chronic inflammation and anabolic pathways, but may promote progression and metastasis in established tumors by enabling metabolic adaptation.

For cancer prevention, maintaining metabolic health through exercise and diet (which activate AMPK) is beneficial. However, for individuals with existing cancer, the role of AMPK is complex and may support tumor survival; therefore, any metabolic interventions should be discussed with an oncologist, as what prevents cancer might not treat it.

Chronic inflammation and obesity suppress AMPK activity, creating a negative feedback loop that exacerbates insulin resistance and metabolic disease.

Weight loss and reducing inflammation can help restore normal AMPK activity, which improves metabolic health. Strategies like exercise and calorie restriction are effective because they counteract the suppression of AMPK caused by obesity and chronic inflammation.

Mitochondrial dysfunction, characterized by reduced oxidative capacity and increased reactive oxygen species (ROS) production, is a central cause of insulin resistance in skeletal muscle, liver, and adipose tissue.

Focus on improving mitochondrial health through regular physical activity (especially aerobic and resistance training) and managing nutrient quality to reduce oxidative stress, as these factors directly influence insulin sensitivity at the cellular level.

Very-low-calorie diets (VLCDs) produce larger initial weight losses than conventional low-calorie diets but do not improve long-term weight maintenance outcomes.

Crash diets (600-800 calories) will help you lose weight faster initially, but you will likely regain it faster and end up at the same weight as if you had lost it slowly. For long-term success, avoid extreme restriction and focus on sustainable habits.

Gut microbiota fermentation of unabsorbed starch and soluble dietary fiber into short-chain fatty acids (SCFAs) provides approximately 10% of daily dietary energy for the host and serves as the primary fuel source for colonocytes, thereby regulating energy homeostasis and metabolic efficiency.

To support your gut's energy regulation, prioritize foods rich in unabsorbed starch and soluble fiber (like resistant starch, oats, legumes). Your gut bacteria ferment these into SCFAs, which provide about 10% of your daily energy needs and fuel your colon cells. This is a natural metabolic process that supports overall energy homeostasis.

Cardiovascular health, specifically arterial pulsatility driven by cardiac output, is a mechanical prerequisite for effective glymphatic fluid transport; conditions like hypertension and heart failure reduce this pulsatility, impairing waste clearance and increasing dementia risk.

Maintain cardiovascular health to support the mechanical force (arterial pulsatility) that drives brain waste clearance. Manage blood pressure, treat heart conditions, and stay physically active to ensure your heart pumps effectively, which in turn helps your brain clear out harmful proteins.

Reducing total dietary fat to 30% or less of calories, and saturated fat to less than 10%, is unlikely to have a substantial, sustained effect on body fatness or breast cancer risk, although it may modestly reduce CHD mortality.

Don't expect that simply cutting fat to 30% of your calories will lead to significant long-term weight loss or breast cancer risk reduction. Focus on overall diet quality, including vegetables, fruits, and whole grains, rather than just fat percentage.

Metabolic inflexibility in insulin-resistant skeletal muscle is characterized by a failure to suppress lipid oxidation during insulin stimulation and a failure to increase lipid oxidation during fasting.

In insulin resistance, your muscles lose the ability to switch fuels efficiently. They fail to burn more fat when fasting and fail to switch to glucose when insulin is high. This 'metabolic inflexibility' leads to lipid accumulation. Improving this flexibility is a key goal for managing insulin resistance.

Reduced mitochondrial density and function predispose individuals to intramyocellular lipid accumulation, which subsequently leads to insulin resistance.

For those with lean insulin resistance or aging-related metabolic issues, maintaining mitochondrial health (via exercise) is crucial to prevent lipid buildup that triggers insulin resistance.

Dietary fiber supplementation leads to small, clinically minor reductions in body weight and body fat percentage, and is not a realistic standalone solution for effective weight reduction.

Do not rely on fiber supplements for significant weight loss. While fiber can help with satiety and minor weight management, its primary value lies in metabolic health, gut health, and cardiovascular protection. Use fiber as part of a broader healthy diet rather than a standalone weight loss strategy.

Orlistat is associated with the lowest probability of achieving ≥5% weight loss and the lowest magnitude of excess weight loss among the five FDA-approved agents studied.

Orlistat is the least effective of the approved weight loss drugs, resulting in the lowest percentage of patients achieving significant weight loss and the smallest average weight reduction. It may be considered if other options are not tolerated, but expectations should be managed accordingly.

Repeated intermittent cold exposure (15-16°C for 6 hours/day over 10 days) recruits human brown adipose tissue (BAT) and increases nonshivering thermogenesis (NST) without requiring skeletal muscle mitochondrial uncoupling or white adipose tissue browning.

To recruit brown fat and boost metabolism, expose yourself to mild cold (15-16°C or ~59-61°F) for 6 hours daily over 10 days. Start with shorter sessions (2 hours) and build up. You do not need to shiver; the goal is mild, tolerable cold. Over time, you will feel more comfortable in the cold, and your body will increase its heat production (nonshivering thermogenesis) via brown fat, potentially increasing daily energy expenditure.

Arm girth alone does not independently cause elevated blood pressure; the association between large arms and high blood pressure is mediated by general adiposity (relative weight).

Having large arms does not cause high blood pressure. However, large arms are often a sign of overall higher body fat, which does raise blood pressure. Focus on overall weight management rather than worrying about arm size affecting your blood pressure reading.

Obesity is associated with a gut microbiota composition characterized by a higher Firmicutes-to-Bacteroidetes ratio and an increased capacity for energy harvest, which contributes to host adiposity.

Your gut bacteria may be more efficient at extracting energy from food than those of lean individuals, potentially contributing to weight gain. While you cannot directly 'eat' a new microbiome, the paper suggests that weight loss and dietary changes can alter this composition, potentially reducing this efficiency.

Lactate is a primary energy substrate for mitochondrial respiration and a major gluconeogenic precursor, formed under fully aerobic conditions rather than solely during oxygen deficiency.

Stop fearing lactate. It is not a waste product or the cause of fatigue; it is a primary fuel your body uses for energy during exercise and recovery. Your body continuously produces and uses lactate, even at rest, to fuel your heart, brain, and muscles.