weight management weight management weight management refers to behaviors, techniques, and physiological processes that contribute to a person's ability to attain and maintain a healthy weight. most weight management techniques encompass long-term lifestyle strategies that promote healthy eating and daily physical activity. moreover, weight management involves developing meaningful ways to track weight over time and to identify ideal body weights for different individuals. part of a series onhuman body weight general concepts obesity (epidemiology) overweight underweight body shape weight gain weight loss gestational weight gain diet (nutrition) weight management overnutrition childhood obesity (epidemiology) medical concepts adipose tissue classification of obesity genetics of obesity metabolic syndrome (epidemiology of metabolic syndrome) metabolically healthy obesity obesity paradox set point theory measurements body adiposity index body mass index body fat percentage body shape index corpulence index lean body mass relative fat mass waist–hip ratio waist-to-height ratio related conditions diabetes (type 1) eating disorder (anorexia • bulimia • binge eating disorder) food addiction hyperthyroidism malnutrition red-s starvation (starvation response) pcos obesity-associated morbidity arteriosclerosis atherosclerosis fatty liver disease gerd gynecomastia heart disease hypertension obesity and cancer osteoarthritis prediabetes sleep apnea type 2 diabetes management of obesity anti-obesity medication bariatrics bariatric surgery dieting (list of diets) caloric deficit exercise (outline) liposuction obesity medicine weight loss camp weight loss coaching yo-yo effect social aspects comfort food fast food (criticism) fat acceptance movement fat fetishism health at every size hunger obesity and the environment obesity and sexuality sedentary lifestyle social determinants of obesity social stigma of obesity weight cutting weight class nutrition is an important part of maintaining a healthy body weight. weight management strategies most often focus on achieving healthy weights through slow but steady weight loss, followed by maintenance of an ideal body weight. however, weight neutral approaches to health have also been shown to result in positive health outcomes. understanding the basic science of weight management and strategies for attaining and maintaining a healthy weight is very important because obesity is a risk factor for development of many chronic diseases, like type 2 diabetes, hypertension and cardiovascular disease. key factors there are many factors that contribute to a person's weight, including: diet, physical activity, genetics, environmental factors, health care support, medications, and illnesses. each of these factors affect weight in different ways and to varying degrees, but health professionals most often stress the importance of diet and physical activity because they can be affected by conscious behavior modification. attaining a healthy weight involves recognition of general techniques such as portion sizing, self-monitoring, and daily diet consistency. once this healthy weight has been attained, maintaining this stable weight additionally involves physical activity and control of an individual's environment and eating patterns. furthermore, healthcare support in the form of primary care medical supervision and following up over time has been shown to be helpful for long-term weight management. the following is a review of some of the key components of weight management in humans. energy balance the science behind weight management is complex, but one of the key concepts that governs weight management is energy balance. energy balance is the phrase used to describe the difference between the number of calories a person consumes and the number of calories that same person expends (a.k.a. burns) in a given time period. there are three possible scenarios when it comes to the energy balance equation: calories consumed (food, drink) = calories expended (basal metabolic rate, physical activity, thermogenic effect of food, acute illness) outcome: weight remains unchanged calories consumed > calories expended also known as positive energy balance outcome: weight increases calories consumed < calories expended also known as negative energy balance outcome: weight decreases the calories a person consumes come from food and drink intake. the calories a person expends comes from their basal metabolic rate and their daily physical activity. the human body is very good at maintaining a neutral energy balance, particularly with a diet composed of fruits, vegetables, and meats so that calories consumed do not substantially exceed calories expended in a given time period and vice versa. this energy balance is regulated by hormones like leptin (suppresses), ghrelin (stimulates), and cholecystokinin (suppresses) which either suppress or stimulate appetite. an image that shows nutrition label information including calorie amounts. diet the quantity of food and drink consumed by an individual may play a role in weight management, as may the types of food and drink a person consumes. for example, intake of sweetened drinks such as sodas or juices can lead to increased energy intake that is not neutralized by a decrease in accompanying food intake. increased portion sizes may also lead to increased energy intake. physical activity running on a treadmill is one form of physical activity that can be done at home or at a gym. physical activity can be related to a person's professional activities, non-work related daily activities like walking or cycling, or it can be in the form of activities such as recreation or team sports. the specific type of activity can be tailored to populations such as children, pregnant women, and elderly adults. tailored activity to one's fitness level also encourages the body to heal properly and prevent any injuries as a result of exercise. physical inactivity leads to less energy expenditure and is a factor that impacts obesity rates in both children and adults. physical inactivity has become a worldwide concern since inactivity also elevates the risk of heart disease. regular physical activity can reduce the risk for noncommunicable diseases like diabetes, heart disease, and dyslipidemia (high cholesterol). basal metabolic rate basal metabolic rate (bmr) is one of the main components of a person's daily energy expenditure. it is defined as the amount of energy that is expended during a given amount of time by a person at rest. this energy at rest is used to pump blood throughout the body, maintain proper brain function, break down toxins, and ensure other bodily functions. technically speaking, bmr is the energy the body expends during the following specific conditions: immediately after waking up, while in a resting state, and after fasting for 12–14 hours. sometimes the term resting metabolic (rmr) is used in place of bmr, but rmr is not solely measured under the previously listed stringent conditions and it is about 10% more than bmr. the bmr is directly proportional to a person's lean body mass. in other words, the more lean body mass a person has, the higher their bmr. bmr is also affected by acute illnesses and increases with burns, fractures, infections, fevers, etc. it can be measured via direct and indirect calorimetry. however, it is also possible to approximately estimate bmr using several equations that factor in a person's age, sex, height, and weight. some of the most popular and accurate equations used to calculate bmr are the original harris-benedict equations, the revised harris-benedict equations, and the mifflin st. jeor equation. the original harris-benedict equations are as follows: bmr (males) in kcals/day = 66.47 + 13.75 (weight in kg) + 5.0 (height in cm) - 6.76 (age in years) bmr (females) in kcals/day = 655.1 + 9.56 (weight in kg) + 1.85 (height in cm) – 4.68 (age in years) the revised harris-benedict equations are as follows: bmr (males) in kcals/day = 88.36 + 13.40 (weight in kg) + 4.8 (height in cm) – 5.68 (age in years) bmr (females) in kcals/day = 447.59 + 9.25 (weight in kg) + 3.10 (height in cm) – 4.33 (age in years) the mifflin st. jeor equation is as follows: bmr (males) in kcals/day = 9.99 (weight in kg) + 6.25 (height in cm) – 4.92 (age in years) + 5 bmr (females) in kcals/day = 9.99 (weight in kg) + 6.25 (height in cm) – 4.92 (age in years) – 161 the mifflin st. jeor equation has been found to be the most accurate predictor of bmr compared to bmr measured by direct and indirect calorimetry. body mass index main article: body mass index body mass index (bmi) is a value used to get a general sense of a person's overall mass and is calculated using a person's height and weight. it is more often used than weight alone to determine if an individual is underweight, normal weight, overweight, or obese. the following two equations can used to calculate bmi depending on the units used for height (meters vs. inches) and weight (kilograms vs. pounds): b m i = weight kg height m 2 =__^ or b m i = weight lbs height in 2 × 703 =__^\times 703} though bmi is often used to help assess for excess weight, it is not a perfect representation of a person's body fat percentage. for example, an individual can have a higher than normal bmi but a normal body fat percentage if they have higher than average muscle mass. this is because excess muscle contributes to a higher weight. since bmi is not a perfect representation of a person's body fat percentage, other measurements like waist circumference are often used to better assess for unhealthy excess weight. the following table shows how different ranges of bmis are often categorized into underweight, normal weight, overweight, and obese: waist circumference may be used as an alternative method to assess weight. classification of overweight and obesity by body mass index (bmi) category bmi underweight < 18.5 normal weight 18.5 – 24.9 overweight 25.0 – 29.9 obesity (class i) 30.0 – 34.9 obesity (class ii) 35.0 – 39.9 obesity (class iii) ≥ 40.0 on average, groups of people with "obese" bmis may have a higher risk of developing illnesses like diabetes, hypertension, dyslipidemia (high cholesterol), liver disease, and some cancers. "underweight" bmis may indicate malnutrition or other health problems. however, bmi has limitations when used to describe individual health rather than describing populations of people. complicating factors thermogenic effect of food the thermogenic effect of food is another component of a person's daily energy expenditure and refers to the amount of energy it takes the body to digest, absorb, and metabolize nutrients in the diet. the amount of energy expended while processing food differs by individual but on average it amounts to about 10% the number of calories consumed during a given time period. processing proteins and carbohydrates has more of a thermogenic effect than does processing fats. medications certain medications can cause either weight loss or weight gain. such side effects are often listed for each medication and should be considered when attempting to manage a person's weight. metanalysis has shown that phentermine and topiramate, pramlintide, naltrexone, bupropion, and liraglutide have been shown to induce weight loss. semaglutide is another anti-obesity drug that is also used for blood sugar control. diseases medical conditions associated with weight gain include hypothyroidism, cushing's syndrome, polycystic ovary syndrome (pcos), and congestive heart failure. medical conditions such as cancer, gastrointestinal illness, psychiatric disorders, infections, endocrine disorders, and neurologic disorders may lead to weight loss. commonly associated with weight gain polycystic ovary syndrome (pcos), which is characterized by insulin resistance and hyperandrogenism, is a common condition that has been linked to obesity. a combination of genetics, lifestyle, and environment appear to contribute to the hormonal changes responsible for weight gain and obesity seen in individuals with pcos.there appears to be a bidirectional relationship between obesity and pcos, whereby pcos increases the risk of obesity and similarly, obesity has been found to exacerbate pcos hormonal differences and clinical symptoms. this photo represents symptoms of cushing's syndrome- a medical condition associated with weight gain.obesity has been linked with pancreatic β-cell dysfunction and insulin resistance. in diabetes, impaired β-islet cells are responsible for the lack of blood glucose control. individuals with a higher body mass index concerning for obesity may have increased levels of hormones, proinflammatory markers, and glycerol, which can contribute to insulin resistance. the combined effects of impaired pancreatic β-islet cells and insulin resistance increase the likelihood of developing diabetes. in individuals with blood sugar levels in the prediabetic range, weight loss was demonstrated to have many benefits including improved glycemic control and a reduced risk of developing type 2 diabetes. commonly associated with weight loss common gastrointestinal disorders associated with weight loss are malabsorption due to celiac disease or chronic pancreatitis. depression and eating disorders such as anorexia nervosa can also contribute to weight loss. infectious causes of