Browse the evidence

The statistical method used to analyze the relationship between muscle hypertrophy and strength gain significantly alters the observed correlation, with hierarchical linear modeling (HLM) revealing stronger within-individual associations than between-subject correlations or ANCOVA.

If you are designing a study or interpreting research on muscle growth and strength, do not rely on simple between-subject correlations (comparing Person A to Person B). Use within-subject analyses (like Hierarchical Linear Modeling) to see how an individual's growth relates to their strength gain. For practitioners, this means individual responses vary wildly; some people get strong without growing much, and some grow without getting proportionally stronger. Do not assume muscle size is the sole driver of strength.

Very low-calorie diets (VLCD) are suitable for short-term use in specific clinical populations, such as those with Type 2 Diabetes (T2D), to improve glycemic control and cardiovascular risk factors, but are not recommended for long-term use or for older adults at risk of sarcopenia.

If you have Type 2 Diabetes, a very low-calorie diet might help your blood sugar and weight quickly, but only under doctor supervision and for a short time. Do not use this if you are older and worried about muscle loss.

GLP-1 receptor agonists (GLP-1RAs) reduce cardiovascular risk and body weight in obese patients with pre-existing cardiovascular disease, regardless of diabetes status, by modulating metabolic pathways, reducing inflammation, and slowing gastric emptying.

If you are overweight or obese and have existing heart disease, GLP-1 receptor agonists like semaglutide are a proven treatment to lower your risk of heart attacks, strokes, and death from heart causes, even if you don't have diabetes. These drugs work by mimicking a hormone that helps control blood sugar, reduces appetite, and slows digestion. While they are injections, their ability to protect your heart and reduce weight makes them a critical tool for secondary prevention. Always discuss with your doctor if this is right for you, especially regarding side effects and dosing.

Obesity pharmacotherapies, specifically high-dose semaglutide and tirzepatide, are highly effective for long-term weight management (>10% loss at 6 months) but remain dramatically underprescribed due to clinician knowledge gaps, safety concerns, and insurance coverage limitations.

If you qualify for obesity pharmacotherapy, discuss semaglutide or tirzepatide with your provider. While highly effective (>10% weight loss), access is limited by insurance. Ask about coverage options, especially if you have cardiovascular risk, as recent policy changes may improve access.

Overreliance on BMI as the sole metric for obesity management hinders clinical implementation and confuses clinicians, leading to suboptimal care; waist circumference is a more useful tool for assessing health risk.

Ask your clinician to measure your waist circumference, not just your BMI. This provides better insight into your cardiovascular risk and helps prioritize obesity management interventions.

Caloric restriction-induced weight loss in nonobese younger adults causes a significant decline in bone mineral density (BMD) at the spine and proximal femur, characterized by increased bone resorption and decreased bone formation.

If you are a younger, normal-weight individual planning to lose weight through caloric restriction, be aware that your bone density may decrease by about 2% over two years. This is likely a normal adaptation to your new, lighter body weight rather than a sign of disease. To mitigate this, ensure you are getting adequate calcium and vitamin D, and consider incorporating weight-bearing or muscle-loading exercises, which have been shown to attenuate bone loss during dieting.

Exercise (particularly weight-bearing and muscle-loading) and higher protein intake can attenuate, but not prevent, the decline in bone mass associated with caloric restriction.

To protect your bones while dieting, prioritize resistance training and ensure you are eating enough protein. These strategies have been shown to reduce bone loss during weight loss, even if they don't stop it completely.

Bioelectrical Impedance Spectroscopy (BIS) is recommended as a feasible, noninvasive, and inexpensive method to assess body fat mass and visceral fat, explaining 80-90% of variance in fat mass compared to gold standards.

Bioelectrical Impedance Spectroscopy (BIS) is recommended for obesity trials as a feasible alternative to expensive imaging. It provides a good estimate of body fat and visceral fat, explaining up to 90% of the variance compared to gold-standard methods like DXA.

Calculated Resting Energy Expenditure (REE) using the Mifflin-St. Jeor equation is recommended over direct calorimetry for large clinical trials due to feasibility, though direct measurement is suggested if resources allow.

For large obesity trials, calculating Resting Energy Expenditure (REE) using the Mifflin-St. Jeor equation is the recommended standard. It is feasible, cost-effective, and correlates well with direct calorimetric measurements.

Metabolic surgery provides superior short-term remission of type 2 diabetes and greater weight loss compared to pharmacotherapy alone, but long-term remission rates decline significantly over time.

Metabolic surgery (like gastric bypass or sleeve gastrectomy) is currently the most effective treatment for obesity and Type 2 Diabetes, offering significantly greater weight loss and diabetes remission rates than medication alone. However, these benefits tend to fade over several years, meaning surgery is not a permanent 'cure' but a powerful tool that often requires ongoing medical management to maintain results.

A multimodal treatment approach combining metabolic surgery with adjuvant pharmacotherapy (specifically GLP-1 agonists or other anti-obesity drugs) is superior to surgery alone for maintaining long-term glycemic control and remission.

For the best long-term results, Type 2 Diabetes treatment should combine metabolic surgery with ongoing medication (like GLP-1 agonists). This multimodal approach significantly increases the chance of keeping diabetes in remission compared to surgery or medication alone, addressing the fact that surgical benefits can fade over time.

Pregnant women with obesity exhibit significantly lower physical activity levels compared to general population guidelines, contributing to lower total daily energy expenditure.

Obese pregnant women tend to be significantly less active than recommended, with the vast majority classified as sedentary. Increasing physical activity could be a key intervention to improve energy balance and prevent excessive weight gain.

Higher intramyocellular lipid (IMCL) content in skeletal muscle myotubes is positively associated with higher insulin sensitivity, greater mitochondrial capacity (ATPmax), and higher physical activity levels, contradicting the linear assumption that high muscle fat causes insulin resistance.

High levels of fat stored inside your muscle cells do not automatically mean you are unhealthy or insulin resistant. In fact, in physically active people, higher muscle fat is linked to better blood sugar control and better heart/lung fitness. Focus on physical activity and mitochondrial health rather than fearing muscle fat, as the context (activity level) determines whether that fat is a fuel source or a metabolic burden.

High sodium excretion (>7 g/day) is associated with a significantly increased risk of major cardiovascular events and all-cause mortality compared to moderate intake (5-6 g/day).

For South American adults, maintaining sodium intake between 5-6 grams per day appears to offer the lowest risk for cardiovascular events and death. Intakes above 7 grams per day significantly increase risk, while intakes below 3 grams per day may also carry increased risk. A universal policy of extreme sodium restriction is not supported by these findings.

Very low sodium excretion (<3 g/day) is associated with a significant increase in major cardiovascular disease risk compared to moderate intake (5-6 g/day).

For South American adults, maintaining sodium intake between 5-6 grams per day appears to offer the lowest risk for cardiovascular events and death. Intakes above 7 grams per day significantly increase risk, while intakes below 3 grams per day may also carry increased risk. A universal policy of extreme sodium restriction is not supported by these findings.

Physical activity improves metabolic health and reduces blood glucose levels independently of weight loss and insulin signaling pathways.

You do not need to lose weight to get the metabolic benefits of exercise. Even if your weight stays the same, physical activity helps your muscles take up glucose without relying on insulin, which is crucial for preventing or managing type 2 diabetes and metabolic syndrome. Focus on consistency rather than just the number on the scale.

Obesity and metabolic disease are driven by a misalignment between behaviors (feeding/fasting rhythms, physical activity) and tissue functions (organ clocks), regulated by circadian molecular clocks in the brain and periphery.

Your body's organs operate on a 24-hour schedule. Try to align your eating and sleeping times with your natural circadian rhythm. Eating large meals late at night or irregularly can disrupt the internal clocks in your liver, muscle, and fat, leading to metabolic issues. Consistent meal times and adequate sleep support better metabolic health.

Setmelanotide, a melanocortin-4 receptor (MC4R) agonist, produces significant weight loss and reduced hunger in patients with severe obesity linked to specific genetic deficiencies (POMC, PCSK1, LEPR, BBS, Alström, SRC1, SH2B1).

For individuals with severe obesity caused by specific genetic mutations (like POMC or LEPR deficiencies), Setmelanotide is a highly effective treatment that significantly reduces body weight and hunger. It requires regular injections, and patients should be prepared for common side effects like skin darkening and injection site reactions, which are generally manageable. This treatment is specifically indicated for genetic forms of obesity, not general weight loss.

Obesity exacerbates cardiovascular disease (CVD) risk and mortality through structural and metabolic mechanisms, including visceral fat deposition, pro-inflammatory cytokine release (TNF-α, IL-1, IL-6), and lipotoxicity from free fatty acids and ceramides.

Obesity is not just about weight; it is a state of chronic inflammation and metabolic signaling disruption that directly harms the heart and blood vessels. Managing obesity requires addressing these underlying biological mechanisms, such as reducing visceral fat and inflammation, to lower cardiovascular risk.

Activation of the AMPK pathway in adipocytes inhibits adipogenesis, enhances insulin sensitivity, promotes thermogenesis, and leads to weight loss, whereas activation in the central nervous system results in weight gain and increased appetite.

While activating AMPK in fat cells can help burn fat and improve insulin sensitivity, activating it in the brain can have the opposite effect, increasing appetite and weight gain. This highlights the complexity of targeting metabolic pathways.

High maximal fat oxidation (MFO) is associated with successful long-term weight loss maintenance, but the underlying mechanism differs from that in individuals who regain weight despite having similarly high MFO.

If you are trying to maintain weight loss, simply having a high capacity to burn fat isn't enough if your body is overloaded with lipids. Successful maintainers typically have higher cardiovascular fitness (V˙ O2max) and better muscle lipid handling proteins (CD36, FABPpm) compared to those who regain weight, who may have high fat oxidation simply because they have more fat available to burn. Focus on building fitness and muscle health rather than just chasing fat oxidation numbers.

Prevention and reversal of the transition from metabolically healthy obesity (MHO) to metabolically unhealthy obesity (MUO) requires multifaceted interventions targeting both adipose tissue intrinsic factors (e.g., promoting adipogenesis) and extrinsic drivers (e.g., hyperinsulinemia, circadian disruption), with lifestyle changes serving as the foundation but often requiring pharmacological or surgical augmentation for substantial weight loss and metabolic correction.

If you have obesity but normal metabolic markers (MHO), do not assume you are safe. Approximately half of people in this category will develop metabolic complications (MUO) over time. Focus on lifestyle changes (diet, exercise) to maintain metabolic health. If lifestyle changes are insufficient to prevent progression, consult a healthcare provider about pharmacological or surgical options to address underlying drivers like hyperinsulinemia or adipose dysfunction.

Hyperinsulinemia acts as an upstream driver of the transition from MHO to MUO by promoting excessive fat accumulation and insulin resistance, and therapies that suppress insulin secretion (e.g., diazoxide, octreotide) may prevent this progression.

If you have MHO and high insulin levels, consider strategies to reduce insulin secretion. This may involve dietary changes (e.g., low carbohydrate, intermittent fasting) or, in some cases, medications that suppress insulin (like diazoxide or octreotide, though these are not standard first-line treatments). Discuss with your doctor whether your insulin levels are driving your metabolic risk.

Eight weeks of resistance training significantly improves phase angle, a marker of cellular health, in obese older women, independent of significant changes in body fat percentage.

If you are an older woman with obesity, engaging in resistance training for just 8 weeks (3 times a week) can significantly improve your cellular health, as measured by phase angle. This improvement happens even if you don't lose much body fat. Focus on performing 8 exercises with 3 sets of 8-12 reps, progressively increasing the weight as you get stronger, rather than just focusing on the number on the scale.