The current prevalence of obesity ranges widely worldwide, from 4.7% to 10% of the population in some African and Asian countries to more than 62% percent in Nauru and Samoa, which have the highest known rates [5,15]. Obesity has infiltrated the developing world in recent years, causing concern to healthcare economists worldwide [2,5]. This has caused a double burden of disease in low-and middle-income countries, where high levels of infectious disease still occur [4,5]. Although malnutrition and famine have historically been and continue to be huge health issues in African countries, obesity is now a looming concern as well [4,5]. In addition to African nations, almost every country in the world is facing an obesity epidemic. The World Obesity Federation estimates that by the year 2025, 1 in 5 adults will be obese, and one-third of those will be severely obese [5]. Furthermore, a report published in 2020 following up on the goal to prevent obesity levels from increasing between 2010 and 2025 globally indicated that most countries have a less than 10% chance of achieving that goal; the United States has a 0.0% chance [5].

The annual direct costs of childhood obesity in the United States as of 2016 are an estimated $14.3 billion [7,21,22]. The total economic effects of obesity may be two to three times this figure, when impaired quality of life, reduced longevity, and other costs outside the medical care system (e.g., lost work days, reduced work performance) are considered [8,23,24]. A systematic review and meta-analysis found that, in 2022 U.S. dollars, the annual total medical costs of childhood obesity and overweight were $237.55 per child. Overweight and obesity also caused a per child increase of $56.52 in nonhospital healthcare expenditures, $14.27 for outpatient visits, $46.38 for medications, and $1,975.06 for hospitalizations. Combined annual direct and indirect costs are projected to be $62.6 billion by 2050 [25]. Globally, obesity and obesity-related diseases (among adults and children) cost $990 billion per year, more than 13% of all healthcare expenditure [5]. These economic burdens are born most heavily by overweight/obese individuals, but also by the general public through higher public and private health insurance costs, diminished employee productivity, and reduced public revenue [26,27]. As today's children—heavier than any generation in history—reach adulthood, these tangible and intangible costs will escalate [5,24].

The pathophysiology of obesity in childhood can be viewed from one of three perspectives: as an imbalance in the intricate homeostatic or energy-balance physiology, as an epidemiologic issue, or as a pathologic issue (focusing on the consequences of excess fat on the risk of future disease) [39]. Changes in energy expenditure may be the result of physical or chemical changes, or both. A heterogeneous group of disorders can result from an extended period of time during which energy intake exceeds the expenditures. Essentially, it is superficially apparent that obese people ingest a greater amount of food relative to their needs [40]. However, whether calorie intake differs between overweight and normal-weight individuals has been the subject of debate. Obese individuals may have increased metabolic efficiency, meaning they may expend relatively fewer calories to maintain body weight. This metabolic state may be the result of lean body mass losses after repeated weight reductions attempts, alterations in body composition, and decreased fat-free mass (FFM). Overall, multiple alterations in metabolic rates set the stage for the development of overweight and obesity [10].

Obesity and obesity-related complications such as type 2 diabetes disproportionately affect minority populations, specifically black Americans and Hispanic Americans of all ages [38]. Studies have found that 19.5% of non-Hispanic black children and adolescents in the United States (2 to 19 years of age) and 21.9% of Hispanic American children and adolescents (2 to 19 years of age) are overweight [17]. Girls and women, particularly those who are black and Hispanic American, are affected more severely than boys and men.

Genetic changes in human populations occur too slowly to be responsible for the obesity epidemic. Yet variants in several genes may contribute to obesity by increasing hunger and food intake [40]. There is a growing body of evidence that describes obesity as a polygenic disorder, with many genes being linked or associated with a predisposition to adiposity [46]. The pathogenesis of polygenic obesity is multifactorial and due to the interaction among genetic, epigenetic, and environmental factors [47]. Scientists have identified more than 1,100 independent genetic loci associated with obesity traits [47]. These genes impact several body systems and processes, including appetite, which partially explains why some infants are indifferent to food while others eat eagerly [2]. Rarely, a specific variant of a single gene (monogenic obesity) causes a clear pattern of inherited obesity within a family [48]. Some research has supported the presence of a human obesity syndrome thought to be linked to genetic defects [49]. Many of these genetic differences are manifested in the body's regulatory hormone levels.

Leptin is a hormone that is mainly released by adipose tissue when fat molecules accumulate. It is also produced in the stomach, ovaries, and skeletal muscle. In those of normal weight, leptin inhibits appetite in satiated individuals [2]. In some overweight individuals, the leptin pathway is inhibited, which results in the lack of signaling to stop eating [2]. Leptin receptor mutations and pro-opiomelanocortin deficiency are both associated with overeating and subsequent obesity [46,50].

Although childhood obesity may be related to specific cultural and national circumstances, universal themes have emerged, including social factors, exercise, advertising, public policy, and the importance of partnership in policy [58]. The obesogenic environment is characterized by increased accessibility and affordability of energy-dense foods in conjunction with declining levels of physical activity [46]. Although community efforts and public policy have been shown to improve childhood obesity rates, studies have indicated that most Americans feel that individuals are responsible for their own obesity and that of their children [38]. However, it is important to recognize that society has created an environment by means of an economic structure that makes processed foods more affordable than fresh foods, and the food industry and mass media market energy-dense foods to children [2]. Evidence is limited regarding specific dietary patterns that may contribute to excessive intake in children and adolescents [44]. There has been considerable debate regarding whether exposure to food advertising affects the incidence of childhood obesity. While a positive correlation between the hours of television viewed, BMI, and obesity has been documented, the exact mechanism by which this occurs are still being investigated [16].

According to the 2019 National Youth Risk Behavior Survey, nearly 60% of high school students had not eaten fruit or drunk 100% fruit juices and 60% had not eaten vegetables in the seven days before the survey [59]. Of the same group, 15.1% had consumed a sugar-sweetened soda (not including diet soda) one or more times per day in the seven days preceding the survey, 10.6% had drunk a sports drink one or more times per day, and 44.6% had drunk three or fewer glasses of plain water each day [59]. A higher percentage of male students than female students had drunk sugar-sweetened soda more than once per day (18.2% versus 11.7%) [59]. Often, individuals do not compensate for the calories consumed in the form of sugar-sweetened beverages with a reduction in solid food intake, partially because liquid forms of energy may be less satiating [60]. In addition to the increase in calorie consumption, average portion sizes have also increased, with sugared drinks increasing from an average 12 ounces to almost 20 ounces [16].

Data from the 2019 National Youth Risk Behavior Survey indicate that, nationwide, 23.2% of students had been physically active 60 minutes or more on all seven days preceding the survey; 49.5% had exercised to strengthen or tone their muscles on three or more days per week; 16.5% had met both aerobic and muscle-strengthening physical activity guidelines; 25.9% had attended physical education classes on all five days in an average school week; and 57.4% had played on one or more sports team [59]. During 2011–2019, a significant decrease occurred in the percentage of students who had been physically active for 60 minutes or more per day on all seven days preceding the survey [59]. The current trend is for schools to decrease the amount of free play or physical activity available to children during school hours [16]. Among high schools in the United States, only 4% require daily physical education or its equivalent for students in all grades for the entire year [60]. Furthermore, only 8% of elementary schools schedule recess on a regular basis. While some schools lack the space for free play, others feel that recess is a waste of time [60].

Sedentary activities have become more prevalent with the evolution of technology and its availability to children and adolescents [2]. According to the 2017 National Youth Risk Behavior Survey, 20.7% of high school students watch three or more hours of television per day during the average school week (down from 42.8% in 1999 and 32.5% in 2013). However, it is clear that other screen usage is replacing television among this age group—43.0% play video or computer games or utilize a computer for activities unrelated to school work for three or more hours per school day [61].

Over the past several decades, the number of dual-income families has increased dramatically, as has the number of women serving as the sole provider for their families. It has been hypothesized that the increase in rate and hours of parental employment may be correlated with the increased rate of overweight and obesity in children [16]. Studies have revealed that children residing in a single-parent household are more likely to be obese than children residing in a two-parent household. Several potential mechanisms have been proposed to explain this phenomenon, including [16]:

Working parents probably rely more heavily than non-working parents on prepared, processed, and fast food, which in general contains increased calories, greater levels of fat, and a decreased nutritional content.

Children left unsupervised after school may make poor nutritional choices and engage in a greater amount of sedentary activities.

Childcare providers may not offer as many opportunities for physical activities and may provide less nutritious snack and meal selections.

Unsupervised children may spend an increased amount of time indoors as a result of safety concerns, watching television or playing video games more readily than engaging in outdoor activities.

There may be a reluctance to label infants as overweight or obese or to delay this diagnosis until toddlerhood. Even if the topic is raised, parents of overweight or obese preschoolers may not perceive their child's overweight status as a problem or health concern and may not be receptive to the discussion. For children, the diagnosis of overweight or obesity is determined with the use of growth charts that give percentages of height, weight, and/or BMI. The Centers for Disease Control and Prevention (CDC) BMI growth charts can be utilized clinically beginning at 2 years of age [62]. BMI is calculated by weight (in kg) divided by height (in meters) squared, or weight (in pounds) divided by height (in inches) squared, which is then multiplied by 703. Diagnosing overweight and obesity in children 5 to 14 years of age may be difficult because there is no standard definition of childhood obesity applied worldwide [4]. Although BMI is utilized in the process of diagnosing overweight and obesity in children, the determination also takes into account age-and sex-specific percentiles. The CDC recommends using the WHO growth charts to diagnose overweight in children younger than 2 years of age and using the CDC charts for children and adolescents older than 2 years of age [62]. Using these growth charts, the following categories have been established [63]:

Underweight: Less than the 5th percentile

Healthy weight: 5th percentile to less than the 85th percentile

Overweight: 85th percentile to less than the 95th percentile

Obese: 95th percentile and greater

In 2007–2008, the prevalence of children 2 to 5 years of age participating in WIC was 10.1%, decreasing to 8.4% in 2011–2012 but again increasing to 13.9% in 2015–2016. The CDC and the U.S. Department of Agriculture analyzed WIC data from 56 U.S. states and territories from 2010 to 2020. During this time, 28 WIC agencies reported significant declines in obesity among children 2 to 4 years of age. The prevalence of obesity reported in 2020 ranged from 8.3% to 19.9% [68]. After adjusting for age, sex, and race/ethnicity, obesity decreased by more than 3% in Nevada, New Jersey, New Mexico, Utah, Virginia, and in two U.S. territories. Obesity increased significantly in Washington (0.5%), North Carolina (0.9%), Hawaii (1.3%), Delaware (1.4%), North Dakota (1.8%), West Virginia (2.1%), and American Samoa (2.4%) [68]. In 2020, 14.4% of WIC participants 2 to 4 years of age had obesity, a decrease from 15.9% in 2010. The prevalence of overweight and obesity combined decreased from 32.5% in 2010 to 29.8% in 2020 [68]. The largest drops were among children 4 years of age, boys, and children who were American Indian or Alaska Native. The prevalence of obesity in 2020 was higher among young children who were Hispanic (17.4%) and American Indian or Alaska Native (18.4%) than among those who were non-Hispanic White (12.3%), non-Hispanic Black (11.9%), or Asian or Pacific Islander (10.7%) [68].

The NHANES interview includes demographic, socioeconomic, dietary, and health-related questions. The examination component consists of medical, dental, and physiologic measurements, as well as laboratory tests administered by medical personnel [69]. NHANES data published in 2020 indicate that Black and Mexican American adolescents 2 to 19 years of age are more likely to be overweight (29.1% and 24.9%, respectively) compared to non-Hispanic White adolescents in the same age-group (14.8%) [70].

There has been little focus on the impact of obesity on respiratory diseases; however, there are clear effects on pulmonary function and inflammation, both of which can increase the prevalence and morbidity of lung disease [82]. The work of breathing is increased in obese individuals, and larger body mass places increased demands for oxygen consumption and carbon dioxide elimination [10]. Increased body weight can also lead to worsening of pulmonary function as a result of the mechanical effects of truncal obesity and the metabolic effects of adipose tissue [82]. This is characterized by increased ventilation of upper lobes and increased perfusion of the lower lobes [10].

Abdominal fat may alter the pressure volume characteristics of the thorax and restrict the descent of the diaphragm, thereby limiting lung expansion, especially if the patient is lying on his or her back [82]. Parents of obese children and adolescents report their children snore loudly and may appear to stop breathing during the sleep cycle, which is indicative of sleep apnea [10]. During sleep apnea, oxygen levels in the blood can diminish dramatically [83]. Obstructive sleep apnea occurs in up to 60% of obese children [84].

The psychologic stress of social stigmatization can cause low self-esteem, which can alter academic and social functioning even into adulthood [44]. The social stigma of weight-based teasing has been identified as a key risk for overall negative psychosocial outcomes among the overweight pediatric population [39,55].

Numerous factors contribute to childhood obesity, including genetics, environment, metabolic, biochemical, psychologic, and physiologic factors. The complex interaction of all of these possible causes makes it unlikely that a single intervention will be successful for all obese children [55;99]. In general, the first-line treatment is behavior changes and lifestyle modification. This should include [55;100]:

Changes to the family's lifestyle

Developmentally appropriate approaches, with parents being the "agents of change" for younger children

Long-term behavioral changes, including monitoring behavior, setting and reviewing goals, rewarding successful changes in behavior, and controlling the environment

Changes in dietary intake, including modified eating patterns, parental modeling of healthy food choices, consumption of lower fat and lower calorie foods, increased vegetable intake, decreased portion sizes, and reduced intake of sweetened drinks

Increased unstructured physical activity, through active transport and access to play equipment, and parental role-modeling of an active lifestyle

Decreased sedentary behavior through limiting combined television and computer (or Internet-connected device) time to less than two hours per day

Pharmacologic therapy for weight loss in children and adolescents remains an area of rapidly evolving research [55]. The AAP recommends that it may be offered to children 8 through 11 years of age as an adjunct to health behavior and lifestyle treatment [55]. Children with more immediate and life-threatening comorbidities, those who are older, and those affected by more severe obesity may require additional therapeutic options [55].

Orlistat is approved for use in obese adolescents 12 years of age and older with a BMI of at least 30, or 27 in the presence of other risk factors. However, the efficacy of orlistat has not been tested extensively in young patients [19,104]. Orlistat acts by inhibiting gastrointestinal lipases and blocking the absorption of up to one-third of fat intake. It has no systemic activity, but it is associated with some side effects, including gastrointestinal effects (e.g., flatulence, fecal fat loss, incontinence, and diarrhea), back pain, and upper respiratory infection [104,108]. Patients using orlistat should take a fat-soluble vitamin supplement [104]. This agent is contraindicated in patients with chronic malabsorption syndrome or cholestasis and should be used with caution in those taking cyclosporine.

Contraindications to adolescent bariatric surgery include [112,113]:

A medically correctable cause of obesity

An ongoing substance abuse problem (within the preceding year)

A disability that would impair adherence to postoperative dietary and medication regimens

Current or planned pregnancy within 12 to 18 months of the procedure

An unwillingness to comprehend and acknowledge the procedure's consequences

Various types of surgical procedures have been used to change eating behavior and induce weight loss. The most commonly used procedures are [108,111,113,115,119]:

Various types of surgical procedures have been used to change eating behavior and induce weight loss. The most commonly used procedures are [108,111,113,115,119]:

Counseling topics that should be addressed with both parents and overweight or obese children/adolescents include [108]:

Food management: Diets are more likely to succeed if individualized according to eating patterns, cultural concerns, degree of motivation, intellect, amount of family support, and financial considerations.

Behavior modification: Behavior and lifestyle modification techniques are utilized to help overweight people cope with an environment that promotes over-eating and inactivity.

Exercise: Dietary management in childhood obesity should be combined with exercise to promote long-term weight loss.

The Child Health Insurance Program Reauthorization Act (CHIPRA) was enacted in early 2009 to increase children's health coverage through Medicaid expansion and the Children's Health Insurance Program (CHIP). The Act includes provisions and some funding to improve child healthcare quality, measure outcomes, and address childhood obesity. In many respects, this starts with the content and quality of primary and preventive health services for children. Having the right care is especially important from birth through 5 years of age, because these earliest years establish health trajectories that extend into adulthood [137]. Likewise, investment of substantial resources will be required to develop effective treatment approaches for normalizing or improving body weight and fitness in children and adolescents and to determine the long-term effects of weight loss on comorbidities of childhood obesity [135].