Browse the evidence

Underweight remains a more prevalent issue than obesity globally for children and adolescents, with the highest burden concentrated in South Asia and parts of Africa.

Do not assume that obesity is the only or main nutrition problem for children. In many parts of the world, underweight is far more common. Nutrition programs must be tailored to address both undernutrition and overnutrition, especially in South Asia and Africa.

Underweight prevalence has decreased globally but remains a significant public health problem in specific regions, particularly South Asia and parts of Africa.

In many parts of the world, being underweight is still a major health risk, particularly in South Asia and Africa. Public health efforts need to address both ends of the BMI spectrum, not just obesity.

The mortality risk associated with high BMI is significantly lower in Black individuals compared to White individuals, particularly in Black women.

For Black adults, the mortality risk associated with higher BMI is lower than for White adults, but it is not zero. Health monitoring should still be prioritized, as elevated BMI still carries some increased risk, especially in White populations.

Glutamine serves as a major energy substrate for immune cells and is required for lymphocyte proliferation and glutathione synthesis.

Your immune cells rely on glutamine for energy. While your body makes some, severe stress or illness can deplete it. Ensuring adequate protein intake supports this natural production.

AMP-activated protein kinase (AMPK) acts as a cellular energy sensor that is activated by metabolic stresses (such as hypoxia, hypoglycemia, or muscle contraction) which increase the AMP:ATP ratio, subsequently switching on catabolic pathways to generate ATP while inhibiting biosynthetic pathways that consume ATP.

Your cells have a built-in energy sensor called AMPK. When you exercise, fast, or experience stress, your energy levels (ATP) drop, causing this sensor to activate. This triggers your body to burn fuel (catabolism) and pause non-essential growth processes (anabolism) to restore energy balance. This is the fundamental biological mechanism behind why exercise and caloric restriction improve metabolic health.

Sedentary behavior is defined as any waking behavior characterized by an energy expenditure ≤1.5 metabolic equivalents (METs) while in a sitting or reclining posture, and it is distinct from moderate-to-vigorous physical activity (MVPA).

Understand that sitting is not just 'not exercising.' It is a distinct behavior with its own health risks. Aim to reduce total sitting time, not just increase exercise.

The doubly labeled water method provides a valid and accurate measurement of energy expenditure in free-living humans when using moderate isotope doses and correcting for isotopic fractionation.

For accurate energy expenditure tracking in free-living individuals, the doubly labeled water method is the most reliable non-restrictive tool available, provided that moderate isotope doses are used and proper corrections for isotopic fractionation are applied.

Doubly labeled water (DLW) is the criterion gold standard for assessing total energy expenditure (TEE) in free-living individuals, but it does not provide information on activity type, intensity, or duration.

If you need to know exactly how much total energy a person burns in their daily life, the Doubly Labeled Water technique is the most accurate method available. However, it is expensive and requires collecting urine samples for 7-14 days, so it is mostly used in research rather than clinical practice. For most people, other objective measures like accelerometers are more practical, even if less precise for total energy.

The global rise in excess body weight, defined as BMI ≥ 25 kg/m², has led to a more than 6-fold increase in the number of obese adults (from 100 million to 671 million) between 1975 and 2016, driven by changes in the global food system and reduced physical activity.

The environment around you is designed to promote weight gain through easy access to cheap, energy-dense food and less physical activity. Recognizing this external pressure helps remove shame and shifts the focus to actionable strategies: choosing nutrient-dense foods and finding ways to move more, even in sedentary environments.

Combining aerobic and resistance training (AT/RT) does not provide additive fat mass or body mass reduction benefits compared to aerobic training (AT) alone, despite requiring double the time commitment.

If you want to lose fat, you do not need to combine aerobic and resistance training. Aerobic exercise alone is just as effective for fat loss as doing both, but it takes half the time. Focus on aerobic exercise for fat loss, and add resistance training only if you specifically want to build muscle.

BMI is a poor index for assessing body composition and obesity risk in children because it does not distinguish between lean mass and fat mass.

Do not rely solely on BMI to assess body fatness, especially in children. It does not distinguish between muscle and fat. More sophisticated measures are needed for accurate assessment.

Small sustained changes in energy intake or expenditure do not produce large, long-term weight changes as predicted by the 3500-kcal rule due to physiological compensation.

Do not expect massive weight loss from tiny lifestyle tweaks like walking an extra mile or skipping two chips daily. Your body will compensate by lowering energy expenditure. To lose significant weight, you need larger, more substantial changes in energy intake or expenditure, or a combination of both, rather than relying on small, sustainable habits alone.

U.S. nutritional surveillance data from NHANES (1971–2010) systematically underreports caloric energy intake, rendering population-level trends in caloric consumption invalid for public health policy.

Do not rely on self-reported dietary recalls (like 24-hour recalls) to track population-level calorie trends or to guide broad public health policies. The data is systematically flawed by underreporting, especially for high-calorie foods. For individual tracking, be aware that you are likely underreporting by ~10-18% of your total expenditure, and this bias increases with higher BMI.

Rapid weight gain in infancy and the second year of life, exceeding normal growth standards, is associated with an increased risk of subsequent obesity.

Monitor your infant's growth using standard growth charts. Avoid rapid weight gain that exceeds these standards, as it is linked to a higher risk of obesity later in life. Focus on balanced feeding practices rather than forcing extra food.

Doubly labelled water (DLW) is the most accurate method for measuring total daily energy expenditure in free-living subjects, providing an error of less than 7-8% over 7-21 days, whereas chamber-based systems are more accurate for long-term measurements but fail to reflect real-life behaviors due to confinement constraints.

For accurate assessment of total daily energy expenditure in real-world settings, doubly labelled water is the gold standard. However, it is expensive and does not break down energy use by activity type, so it is primarily used in research rather than clinical practice.

Dual-energy X-ray absorptiometry (DXA) is the current reference standard for assessing body composition in clinical research due to its accuracy, low radiation, and ability to distinguish between fat mass, lean mass, and bone mineral content, although it has limitations regarding hydration status assumptions.

If you need an accurate assessment of your body composition (fat vs. muscle vs. bone), DXA is the most accessible and reliable clinical standard available today. It provides a detailed breakdown that BMI cannot, helping to identify hidden risks like visceral fat or muscle loss.

Postoperative Basic Metabolic Rate (BMR) decreases in proportion to weight loss after bariatric surgery, with no difference in BMR reduction between LGBP and LVBG, refuting the theory of postoperative hypermetabolism.

After bariatric surgery, your metabolic rate decreases as expected with your weight loss. There is no 'hypermetabolic' state that drives weight loss; instead, the reduction in energy expenditure is proportional to the loss of body mass.

Higher cumulative energy intake (caloric dose) during the first week of ICU stay is inversely associated with recovery speed; the lowest caloric doses are associated with the fastest recovery.

When managing nutrition in the first week of critical illness, aiming for high caloric targets is counterproductive. Data shows a linear relationship where higher calorie intake leads to slower recovery. Clinicians should prioritize tolerating lower caloric intakes (hypocaloric feeding) rather than aggressively pushing calories, as this is associated with faster ICU discharge.

Overall US adult obesity prevalence increased significantly from 2011 to 2018, with non-Hispanic Black individuals showing the highest prevalence but leveling off trends.

Overall obesity rates in the US are rising. To maintain health, focus on sustainable lifestyle changes such as balanced nutrition and regular physical activity, regardless of broader demographic trends.

During caloric overfeeding, dietary protein intake (5-25% of energy) does not significantly affect the amount of body fat gained; fat gain is determined by caloric surplus alone.

If you are eating in a caloric surplus, your body will store the excess energy as fat regardless of how much protein you eat. High protein diets do not prevent fat gain during overfeeding; they only change how much of the total weight gain is fat versus muscle and how much energy is burned.

Fasting and energy restriction upregulate the NPY system (increasing mRNA and peptide content in the arcuate nucleus), while refeeding and high-fat/high-energy diets tend to downregulate or decrease NPY expression as a counter-regulatory mechanism.

Your brain's hunger signal (NPY) increases when you fast or restrict calories to drive you to eat. However, chronic overconsumption of high-fat or high-energy foods may actually suppress this specific signal over time as a counter-regulatory response.

Smoking cessation increases the short-term risk of type 2 diabetes, but this risk is directly proportional to post-cessation weight gain and does not mitigate the long-term reduction in cardiovascular and all-cause mortality.

Quitting smoking is the single most important step for longevity, regardless of what happens to your weight. While you might gain weight and see a temporary spike in diabetes risk (especially if you gain >10kg), the reduction in your risk of dying from heart disease or other causes is massive and sustained. Do not let the fear of weight gain prevent you from quitting.

Common genetic variants in the FTO gene (specifically rs9939609) are associated with a modest increase in BMI and a higher risk of obesity, primarily by influencing energy intake and satiety rather than physical activity.

If you carry the FTO risk variant, be aware that it may predispose you to higher energy intake and lower satiety. Focus on managing portion sizes and food quality, as your genetic risk is linked to how much you eat, not how much you move.

Vibration exercise provides an insufficient stimulus to significantly enhance cardiovascular indices (heart rate, blood pressure) compared to conventional aerobic exercise, making it a safe but limited option for cardiovascular conditioning.

Do not rely on vibration exercise for heart health. It raises heart rate only slightly. It is safe for those who cannot do traditional cardio, but it does not replace aerobic exercise for cardiovascular conditioning.