Browse the evidence

Time-restricted eating (TRE) significantly increases low-density lipoprotein (LDL) cholesterol levels in adults with overweight and obesity, although it does not significantly alter total cholesterol, HDL, or triglycerides.

While TRE helps reduce body fat, be aware that it may slightly increase your LDL ('bad') cholesterol. This increase was statistically significant but the authors note it does not pose a significant safety concern for most. If you have existing heart conditions or high cholesterol, monitor your levels and consult a doctor.

Adaptive thermogenesis (AT) is primarily mediated by hormonal signals (leptin and insulin) that downregulate substrate cycling in skeletal muscle, reducing energy expenditure to preserve fat stores.

Understanding that hormones like leptin and insulin drive metabolic slowdown helps explain why weight loss stalls. This is not just 'willpower'; it is a hormonal defense of fat stores. Strategies that maintain muscle mass and avoid extreme deficits may mitigate the severity of this hormonal suppression.

Twice-per-week intermittent fasting (5:2 diet) is not superior to continuous energy restriction for weight loss or insulin resistance in night shift workers, though it may offer specific lipid benefits.

For night shift workers, a 5:2 intermittent fasting plan (eating ~500 kcal on 2 non-consecutive days) is just as effective for weight loss as eating slightly less every day. It does not offer superior metabolic benefits like insulin sensitivity, but it may help lower LDL cholesterol. Choose the method that fits your schedule best, as adherence is key.

Long-term adherence to a low-carbohydrate (LC) diet (defined as <45% energy from carbs) results in significant weight regain and increased triglyceride levels compared to a low-fat (LF) diet in overweight or obese adults.

If you are trying to lose weight long-term, a strict low-carb diet (<45% carbs) may not be better than a low-fat diet and could actually lead to more weight regain and higher triglycerides after a year. Focus on sustainable calorie restriction and food quality rather than extreme macronutrient restriction. Low-fat diets showed better or equivalent long-term weight maintenance and lipid profiles in this review.

A 12-month 4:3 intermittent fasting protocol does not produce different changes in fasting appetite-related hormones (leptin, ghrelin, PYY, BDNF, adiponectin) compared to daily caloric restriction when energy deficits are matched.

Don't expect intermittent fasting to magically fix your hunger hormones differently than daily calorie counting. The benefit of 4:3 IMF comes from how it changes your eating behaviors and psychological relationship with food, not from a unique hormonal advantage.

A modest reduced-calorie diet does not significantly alter plasma levels of Brain-Derived Neurotrophic Factor (BDNF) or glycemic factors (glucose, insulin, HOMA-IR) in overweight/obese adults with cardiovascular risk factors over a two-month period.

While cutting calories helps your cholesterol and blood pressure, it might not immediately change your blood sugar levels or brain-derived neurotrophic factor (BDNF) levels in just two months. This doesn't mean the diet isn't working; it means these specific markers may take longer to respond or may not respond in everyone, especially if you are already on medication. Focus on the improvements you can see, like weight and lipid profiles.

Time-restricted eating (TRE) does not significantly improve BMI, fat mass, blood lipids, glucose, or blood pressure in overweight and obese women compared to control groups.

Do not expect TRE to automatically fix your BMI or cholesterol levels if you do not also manage your total calorie intake. While it helps with weight and insulin, it does not significantly alter fat mass or blood pressure on its own in this population.

Time-restricted feeding does not significantly improve cardiometabolic markers (HDL, LDL, triglycerides) compared to control diets in overweight or obese adults.

Do not expect time-restricted feeding to automatically improve your cholesterol or triglyceride levels. While it helps with weight loss, you may need to focus on other dietary factors or exercise to improve your lipid profile.

Combining Time-Restricted Eating (TRE) with Energy Restriction (ER) provides no additional benefit for weight loss or fat mass reduction compared to TRE alone.

If you are already practicing Time-Restricted Eating, you do not need to add explicit calorie counting or energy restriction to achieve weight loss. TRE alone is sufficient for significant fat and weight reduction. Adding calorie restriction does not provide extra benefits for weight loss in this context.

Increasing exercise dose (frequency, duration, intensity, or total energy expenditure) does not increase the magnitude of energy compensation (the body's compensatory response), meaning higher doses are required solely to overcome a fixed compensatory threshold rather than to avoid greater compensation.

If you are exercising to lose weight, doing more exercise does not cause you to compensate by eating more or storing more fat than a smaller amount of exercise would. The body's 'compensatory response' is roughly fixed (around 1,000 kcal/week). To lose fat, you must simply exceed this threshold. Therefore, higher exercise doses are not 'futile' due to compensation; they are necessary to create a net deficit large enough to result in fat loss.

The human gut microbiome contains a shared core of prevalent bacterial species and functions (the minimal gut metagenome) that are essential for gut ecosystem homeostasis, including the degradation of complex sugars and synthesis of short-chain fatty acids.

Your gut bacteria share core functions with others, specifically breaking down complex plant sugars into energy for your cells (SCFAs). You can support this shared machinery by eating diverse fibers (pectin, sorbitol, cellulose) that these microbes are evolved to process, regardless of your specific bacterial species mix.

Estimating body fat percentage from skinfold thickness requires using the logarithm of the skinfold measurements to achieve a linear relationship with body density, as the raw relationship is non-linear.

If you are using skinfold calipers to estimate body fat, do not simply add the millimeter readings and plug them into a standard linear formula. You must use the specific regression equations provided by Durnin and Womersley that utilize the logarithm of the skinfold sum. Using raw numbers will lead to inaccurate results, especially for individuals with higher body fat percentages.

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.

Chronic inflammation driven by macrophage infiltration into white adipose tissue (WAT) is a primary causal mechanism for obesity-induced insulin resistance, rather than merely a correlative symptom.

In obesity, fat tissue becomes inflamed due to macrophage infiltration, which actively blocks insulin from working properly. This is a biological defense mechanism, not just a passive result of having extra fat. Treating the underlying inflammation (e.g., via medications like TZDs shown in the study) may improve insulin sensitivity independently of immediate weight loss.

Prebiotics can confer health benefits at extraintestinal sites (e.g., skin, vagina, brain) through indirect mechanisms mediated by gut microbiota changes.

Prebiotics can help conditions outside the gut, like skin health or mood, by changing the gut bacteria which then send signals to other parts of the body.

Obesity spreads through social networks via interpersonal induction, where a person's risk of becoming obese increases significantly if their friends, siblings, or spouses become obese, independent of geographic proximity.

Your social circle matters for your weight. If your close friends or family members gain weight, your own risk of gaining weight increases, likely due to shifting norms and shared behaviors. To maintain a healthy weight, consider how your social network influences your habits and seek supportive relationships that align with your health goals.

Diet-induced obesity causes adipose tissue macrophages (ATMs) to switch from an anti-inflammatory M2 phenotype to a pro-inflammatory M1 phenotype, which drives insulin resistance.

This research highlights that obesity triggers an immune response in fat tissue that actively blocks insulin action. While this paper focuses on mice, it suggests that reducing inflammation in fat tissue (potentially through weight loss, exercise, or anti-inflammatory diets) may be crucial for restoring insulin sensitivity, not just reducing calorie intake.

Aspirin should be used infrequently in the routine primary prevention of atherosclerotic cardiovascular disease (ASCVD) because of lack of net benefit.

Do not start taking daily aspirin for heart disease prevention without discussing it with your doctor. For most people in primary prevention, the risk of bleeding outweighs the benefits. Focus on lifestyle changes like diet and exercise instead.

Hypoadiponectinemia (low plasma adiponectin) in obesity and type 2 diabetes is primarily driven by insulin resistance and hyperinsulinemia rather than adiposity (body fat percentage) alone.

If you have low adiponectin, focusing solely on weight loss may not restore levels if insulin resistance persists. Prioritize interventions that improve insulin sensitivity (like resistance training and carbohydrate management) as these are more strongly correlated with healthy adiponectin levels than body fat percentage alone.

Elevated plasma free fatty acid (FFA) concentrations cause a dose-dependent inhibition of insulin-stimulated glucose uptake in skeletal muscle, primarily by reducing glycogen synthesis and secondarily by reducing carbohydrate oxidation.

High levels of free fatty acids in your blood can block insulin from helping your muscles take up glucose. This happens through two main pathways: it stops your muscles from storing glucose as glycogen and reduces the amount of glucose you burn for energy. This effect is dose-dependent, meaning higher fat levels lead to greater insulin resistance. For healthy individuals, this suggests that managing fat metabolism is crucial for maintaining insulin sensitivity.

Elevated plasma free fatty acids (FFA) and/or glycerol increase hepatic glucose output (HGO) by approximately 50%, contributing to hepatic insulin resistance.

High levels of fat in your blood can cause your liver to produce more glucose, even when you are trying to lower blood sugar. This happens because fat and its byproduct, glycerol, interfere with insulin's ability to stop the liver from making glucose. This contributes to higher blood sugar levels and insulin resistance.

High plasma FFA concentrations impair muscle glycogen synthase (GS) activity, but this impairment occurs late (after 4-6 hours) and is associated with increased glucose-6-phosphate levels.

High levels of fat in your blood can eventually impair the enzyme that helps store glucose as glycogen in your muscles. However, this effect takes several hours to develop and requires high fat levels.

Medium plasma FFA concentrations reduce glycogen synthesis by impairing glucose transport or phosphorylation, leading to decreased glucose-6-phosphate levels, before glycogen synthase activity is affected.

Even moderate levels of fat in your blood can interfere with how your muscles take up and process glucose, before they affect the enzyme that stores it as glycogen. This happens by reducing the amount of glucose-6-phosphate, a key intermediate.

Gut microbiota composition is not a single optimal state but a personalized ecosystem shaped by early-life factors (birth mode, feeding), age, and ongoing lifestyle variables (diet, exercise, BMI), where health is defined by functional balance rather than specific taxonomic abundance.

Do not chase a single 'ideal' bacterial profile. Focus on maintaining a diverse, balanced microbiome through personalized lifestyle choices: prioritize fiber-rich plant foods, regular exercise, and minimizing unnecessary antibiotic use. Recognize that your gut health is shaped by your unique history (birth, early diet) and current habits.