Browse the evidence

The guidelines mostly agree, although there are slight differences in their recommendations.

Practitioners should be aware of both the consensus and differences in the guidelines.

A 6-month dietary intervention producing a 500 kcal/day energy deficit yields similar weight loss outcomes regardless of an individual's high or low genetic predisposition to higher BMI, as measured by genome-wide polygenic scores.

If you are overweight or mildly obese, a standard dietary intervention creating a 500 kcal/day deficit will likely help you lose weight, regardless of your genetic risk for obesity. You do not need a specialized or 'genetic' diet to succeed; standard caloric restriction is effective for everyone in this range.

Intermittent Fasting (IF) is defined as repetitive fasting periods lasting up to 48 hours each, including Time-Restricted Eating (TRE) and Alternate-Day Fasting (ADF).

Intermittent Fasting means you fast repeatedly, with each fast lasting no more than 48 hours. This includes popular methods like Time-Restricted Eating (eating within a daily window) and Alternate-Day Fasting. You do not need to restrict calories during eating windows if you choose TRE.

Time-Restricted Eating (TRE) is defined as restricting food and caloric beverage intake to a specific daily period, resulting in a fasting window of at least 14 hours, with no explicit limit on energy intake during eating hours.

Practice Time-Restricted Eating by limiting your daily food and calorie-containing drink consumption to a window of at least 14 hours. You do not need to restrict the amount of food you eat during this window.

Weight loss interventions trigger physiological countermeasures, specifically adaptive thermogenesis (reduced resting energy expenditure) and increased appetite drive, which persist long-term and make weight maintenance difficult.

Understand that after losing weight, your body will biologically fight to regain it by lowering your calorie burn and increasing hunger. This is a normal physiological response, not a personal failure. Long-term maintenance requires strategies that account for these biological changes, such as higher protein intake or resistance training, rather than relying on willpower alone.

Metabolic adaptations to weight loss (e.g., decreased energy expenditure) act to resist weight change and contribute to weight regain.

Expect metabolic adaptations when losing weight. These adaptations resist weight change and contribute to regain, making sustained weight loss challenging.

Prolonged calorie restriction (25% deficit) in nonobese overweight adults induces metabolic adaptation, reducing 24-hour energy expenditure by ~6% more than expected from the loss of fat-free mass alone.

If you restrict calories for 6 months, your body will burn fewer calories than expected for your new size. This is a normal survival mechanism, not a failure. To manage this, you may need to adjust your calorie targets or increase activity as you lose weight, rather than assuming your old maintenance calories will still apply.

Prolonged calorie restriction reduces DNA damage (measured by comet assay) in nonobese overweight adults, while protein carbonyl levels remain unchanged.

Calorie restriction reduces DNA damage, a key factor in aging. This benefit was seen across different types of calorie restriction (moderate, with exercise, and very low-calorie), suggesting that reducing energy intake protects DNA integrity.

Among healthy, never-smoking white adults, a BMI of 20.0 to 24.9 is associated with the lowest all-cause mortality, while both overweight (BMI 25.0-29.9) and obesity (BMI ≥30.0) are associated with significantly increased mortality risk.

For non-smoking adults without major chronic diseases, maintaining a BMI between 20.0 and 24.9 is associated with the lowest risk of death. Being overweight or obese increases this risk, with the risk rising significantly as BMI increases beyond 30.

Higher body weight and greater weight gain during adulthood are strongly associated with an increased risk of coronary heart disease in women, independent of other risk factors.

Maintain a healthy body weight and avoid significant weight gain as you age. This study indicates that carrying extra weight, especially gaining weight in adulthood, significantly raises your risk of heart disease. Focus on sustainable lifestyle habits that support a stable, healthy weight rather than quick fixes.

Chronic energy imbalance (caloric excess) drives adipocyte hypertrophy and hyperplasia, leading to endoplasmic reticulum (ER) and mitochondrial stress, which causes systemic insulin resistance and inflammation.

Focus on correcting the root cause: energy imbalance. Reducing caloric intake and increasing energy expenditure reverses the cellular stress (ER and mitochondrial) that drives obesity-related disease. Lifestyle modification is the most promising intervention.

Modest weight gain (4-10 kg) during adulthood significantly increases the risk of coronary heart disease, independent of physical activity levels.

Even small weight gains of 4-10 kg during adulthood can increase your risk of heart disease. This risk exists even if you are physically active. Maintaining a stable weight is an important part of heart health prevention.

Sustained caloric restriction induces metabolic adaptations, specifically a significant decrease in Resting Metabolic Rate (RMR) residual and Total Daily Energy Expenditure (TDEE) residual, indicating increased metabolic efficiency.

When you sustain a calorie deficit, your body becomes more metabolically efficient, burning fewer calories at rest and during activity than expected for your new weight. This is a normal adaptation, not a failure, and helps explain why weight loss plateaus occur.

Long-term consumption of sugar-sweetened beverages (SSBs) is positively associated with increased total and cardiovascular disease (CVD) mortality in a graded, dose-dependent manner.

Limit sugar-sweetened beverages to less than one serving per month to minimize mortality risk. Each additional daily serving increases the risk of death by approximately 7%, primarily due to cardiovascular causes. Replace SSBs with water or unsweetened alternatives.

Rapid weight loss (≥1 kg/week) significantly increases the risk of developing symptomatic gallstones in middle-aged women, whereas gradual weight loss does not.

If you are losing weight rapidly (1 kg or more per week), be aware that your risk of developing symptomatic gallstones more than doubles compared to those who lose weight more slowly. To minimize this risk, aim for a gradual weight loss of less than 1 kg per week, especially if you are a middle-aged woman.

Higher baseline BMI and weight gain over 15 years are significant, robust predictors of developing metabolic syndrome, independent of other risk factors.

Maintaining a healthy BMI and avoiding weight gain is the single most important factor in preventing metabolic syndrome. If you gain weight, your risk increases significantly, but you can mitigate this by maintaining regular physical activity.

Long-term moderate calorie restriction (25% reduction) significantly reduces circulating inflammatory markers (CRP, TNF-α, WBC, leptin) in non-obese adults without impairing cell-mediated immunity.

If you are a healthy, non-obese adult, reducing your daily calorie intake by 25% for two years significantly lowers your systemic inflammation (a key driver of aging and chronic disease) without weakening your immune system. Ensure you meet micronutrient needs, potentially with supplements, to support this long-term change.

Metabolic surgery leads to significant and durable weight loss (mean 50-70% Excess Weight Loss) and improvement in cardiovascular risk factors (hypertension, dyslipidemia) compared to non-surgical weight management.

Metabolic surgery is the most effective treatment for significant and durable weight loss. While non-surgical methods rarely achieve more than 5% long-term weight loss, surgery can lead to 50-70% excess weight loss. This weight loss also improves blood pressure and cholesterol levels.

Long-term calorie restriction (25% reduction for 2 years) in healthy nonobese adults improves mood, general health, and sexual drive without negatively affecting quality of life, sleep, or stress levels.

If you are a healthy, nonobese adult, reducing your calories by 25% for two years is unlikely to harm your mental health or quality of life. In fact, it may improve your mood, reduce tension, and boost your sense of general health and sexual drive. You do not need to fear that eating less will make you miserable.

Type 2 diabetes risk is more strongly associated with adult weight gain, whereas obesity-related cancer risk is more strongly associated with BMI in early adulthood.

To prevent type 2 diabetes, preventing adult weight gain is critical. To prevent obesity-related cancers, maintaining a lean BMI in early adulthood (by age 21) is more important. Prioritize early adulthood leanness for cancer risk reduction and adult weight stability for diabetes risk reduction.

Sustained moderate caloric restriction (average 11.9% reduction over 24 months) improves aging-related biomarkers and metabolic health without causing adverse psychological or behavioral outcomes in healthy, non-obese adults.

To improve aging biomarkers and metabolic health, aim for a moderate, sustained reduction in calorie intake (around 10-12%) over a long period (e.g., 2 years). This should be done with professional guidance, using behavioral strategies to maintain adherence, and ensuring you take a multivitamin and calcium supplement to prevent deficiencies. This approach is safe and effective even for non-obese individuals.

Weight loss slows down and eventually plateaus because energy expenditure decreases as body composition shifts (specifically, loss of metabolically expensive lean tissue), creating a new steady state where energy intake equals expenditure.

Expect your weight loss to slow down and stop at a new 'plateau' even if you keep eating the same amount less. This happens because your body burns fewer calories as it gets smaller and loses muscle. To continue losing weight, you must further reduce calories or increase activity to match your new, lower energy expenditure.

Total daily energy expenditure (TDEE) in healthy, free-living, non-athlete individuals is primarily composed of resting energy expenditure (approx. 60%), physical activity energy expenditure (approx. 30%), and the thermic effect of food (approx. 10%).

To understand your daily energy needs, recognize that most energy (60%) is used just to keep your body running at rest, about 30% goes to movement, and 10% is used to digest food. This breakdown helps in estimating caloric requirements for health maintenance.

Physical activity energy expenditure (PAEE) is highly variable among individuals and can range from almost none in bedridden individuals to approximately 50% of TDEE in highly active individuals.

Your physical activity level is the most variable component of your daily energy expenditure. Increasing your movement can significantly increase your total energy needs.