Introduction

Burden of Disease

Pediatric obesity is an epidemic that affects over 340 million children and adolescents worldwide. In the United States, the Centers for Disease Control and Prevention (CDC) estimates obesity affecting a total of 14.7 million children and adolescents at a prevalence rate of 19.7% [1].

Obesity has important health-related and thus economic consequences. Children with obesity are more likely to suffer from metabolic, musculoskeletal, respiratory, liver, and cardiovascular diseases [2, 3]. They are at increased risk for depression, low self-esteem, body image disorders, anxiety, and eating disorders [4,5,6]. Additionally, children suffering from obesity have an increased likelihood of becoming adults with obesity [7]. Approximately 55% of children with obesity will go on to be adolescents with obesity and 80% of these adolescents will become adults with obesity [7]. The persistence of obesity from adolescence to adulthood increases morbidity and mortality [8,9,10].

Obesity has a direct impact on healthcare costs by increasing healthcare utilization and productivity loss [11, 12]. Childhood obesity is estimated to increase healthcare costs in the US by $5 billion annually. It is estimated that by 2050, the adolescent overweight population is projected to cause $13.62 billion in annual direct medical costs and $49.02 billion in annual indirect costs [13].

Definitions

Childhood obesity requires classifications separate than those used in adults; body mass index (BMI) categories vary with age and sex in the pediatric population [14]. The CDC developed BMI-for-age charts two decades ago to help health care providers identify children who were overweight and at risk of developing obesity. However, the BMI-for-age growth charts did not appropriately include children with extremely high BMIs. In 2022, the CDC released the Extended BMI-for-age growth charts in 2022 to include extremely high BMIs [15].

These new categories defined overweight as BMI range from the 85th percentile to less than the 95th percentile, obesity as the 95th percentile or greater, and severe obesity as ≥ 120% of the 95th percentile for age and sex. Obesity is also expanded by the American Academy of Pediatrics (AAP) into classes 1, 2, and 3; class 1 is BMI ≥ 100 to < 120% of the 95th percentile; class 2 is BMI ≥ 120 to < 140% of the 95th percentile; and class 3 is BMI ≥ 140% of the 95th percentile. BMI equivalents for these classes are ≥ 30, ≥ 35, and > 40 kg/m2. Additional classes exist for adults (class 4 BMI ≥ 50 kg/m2 and class 5 BMI ≥ 60 kg/m2), but such groups have not been defined for the pediatric population [16].

Management

Prevention of obesity is the ideal solution to the epidemic but it does not address the concerns of children and families currently struggling with obesity. Management strategies are divided into:

  1. 1.

    Lifestyle modifications

  2. 2.

    Pharmacologic management

  3. 3.

    Surgical management

Lifestyle modifications are discussed elsewhere in this issue of Current Obesity Reports. The impact of these modifications is statistically significant but is too small in practical terms to reduce the complications associated with obesity [17].

The scope of pharmacologic treatment has greatly expanded in the last five years with the introduction of glucagon-like peptide-1 (GLP-1) and gastric inhibitory polypeptide (GIP) agonist agents. These incretin agents produced in the intestine increase insulin secretion by stimulating the pancreatic beta cells via the cyclic adenosine monophosphate pathway. In addition, incretin agents function as appetite suppressors and early satiety inducers.

Liraglutide is the first GLP-1 receptor agonist approved by the FDA (2020) for use in adolescents with obesity between the ages of 12 and 17 [18]. In a randomized control trial, liraglutide 3.0 mg injected subcutaneously once daily reduced BMI by at least 5% in 45% of users and 10% in 29% [19•].

A much newer agent, semaglutide (GLP-1 receptor agonist) was approved by the FDA (2022) in adolescents with BMI over 95% for age and gender [20]. The results of the STEP-TEENS randomized control trials have shown a mean change in BMI of − 16.1% after 68 weeks with once-a-week semaglutide injection as compared to 0.6% with placebo [21•]. Additionally, 73% of participants in the semaglutide arm lost at least 5% of their weight compared to 18% of patients on placebo agents, while 62% versus 8% lost at least 10%, 53% versus 5% lost at least 15%, and 37% versus 3% lost at least 20% of their starting bodyweight [21•]. In a follow-up study, more adolescents (44.9% versus 12%) achieved normal weight body mass index [22•]. It is critical to understand that this study although profound evaluated the outcome of semaglutide in adolescents with a mean BMI of 37. In fact, two-thirds of the participants were under a BMI of 40 and the maximum BMI was less than 45. Most of the adolescents who achieved normalized weight were in class 1 obesity category (57%).

A combination agent (GLP-1/GIP) tirzepatide has recently been shown to be much more effective in adults who struggle with obesity [23]. Fifty percent of the participants had a reduction of 20% in body weight over 72 weeks with once-a-week subcutaneous injections. Similar to the semaglutide trial, mean BMI for this study was 37 with over two-thirds of the participants under a BMI of 40, and the maximum BMI was less than 45. FDA approval for this novel drug is pending. Trials in adolescents are pending.

Long-term outcomes for incretin agents are unknown. Data on outcomes after discontinuation of the agents are not clear, and the randomized control trials for both semaglutide and tirzepatide had adverse reactions in 6–11% of participants with 4–6% of patients using the agents stopping their use [21, 23]. Furthermore, insurance companies are not consistently covering these agents.

Phentermine/topiramate, a combination agent effective in adults with obesity, was recently approved by the FDA (2022) in adolescents aged 12 to 17. A 56-week randomized double-blind trial showed a mean difference in BMI of − 10.4% between the top dose and placebo. In addition, among participants receiving the top dose compared to placebo, 46.9% achieved a BMI reduction of ≥ 5%, 42.5% a BMI reduction of ≥ 10%, and 28.3% a BMI reduction of ≥ 15%. Mean BMI for this trial was also 37 kg/m2 [24]. The overall incidence of any adverse events was similar across placebo, mid-dose, and top-dose groups.

Prior to these agents, only orlistat was approved by the FDA for long-term use for weight loss in adolescents; however, it has little significant impact on obesity in children [25].

Surgical Management of Obesity in Children

Weight loss surgery, better defined as Metabolic and Bariatric Surgery (MBS), has been used since the 1960s in adults [26, 27]. Laparoscopic approaches increased the utilization and safety of MBS, resulting in a surge of procedures occurring in the 1990s and early 2000s, with Laparoscopic Roux-en-Y Gastric Bypass (LRYGB) quickly becoming the procedure of choice [27]. LRYGB reroutes the normal flow of the food bolus by bypassing most of the stomach, duodenum, and part of the jejunum. A small pouch created from the stomach opens into the distal small intestine allowing a more direct entry into the gastrointestinal tract. This procedure is considered restrictive due to the size of the residual stomach and malabsorptive due to the bypass of the proximal intestine. LRYGB is technically complex and has significant complications and reoperation rates [28,29,30].

Laparoscopic sleeve gastrectomy (LSG) was introduced in the 1990s as the first stage procedure for those patients deemed to high risk for Roux-en-Y Gastric Bypass (RYGB) [31]. As experience grew with LSG and outcome data expanded, it became clear that LSG had a nearly similar efficacy profile with a much higher safety profile [32]. LSG is now the primary Metabolic and Bariatric Surgery (MBS) procedure in the United States in adults [33]. LSG involves excision of a large portion of the stomach along the greater curvature to leave roughly 20% of the stomach in situ. This is considered a restrictive procedure, but evidence shows that there is a central mechanism of action by reducing the ghrelin production by the stomach [34]. LSG is technically simpler and has lower short-term and long-term complication rates than RYGB [35, 36]. There are two other critical aspects of LSG. The first one is the limited impact LSG has on macro and micronutrient deficiencies compared to RYGB [37]. The second is that LSG can be converted to RYGB or other MBS procedures if patients fail to achieve weight and health goals with LSG.

Early reports for MBS in children and adolescents described the successful use of open RYGB in the 1970s and 80 s [38, 39]. Laparoscopic approaches for MBS in this age group were described in the early 2000s with successful weight loss and improved comorbidities [40]. Laparoscopic adjustable gastric banding (AGB) was also used for children in the early 2000s but it has fallen out of favor and will not be discussed further [41]. Laparoscopic sleeve gastrectomy seems to have been reported in children for the first time in 2008 [42]. Similar to adults, LSG is now the primary procedure in teenagers and adolescents globally.

MBS Outcomes in Adolescents and Teenagers

Weight Loss

Current bariatric surgery procedures, specifically Laparoscopic Roux-en-Y Gastric Bypass (LRYGB) and laparoscopic sleeve gastrectomy (LSG), have strong evidence supporting their effectiveness in achieving both short-term and long-term weight loss in pediatric patients [43, 44, 45•]. A recurring issue when reviewing outcomes in children is the mixed use of excess weight loss, excess BMI loss, or total weight/BMI loss percentages to report outcomes after surgery. As results for newer pharmacologic agents are described in total weight or BMI percentage loss, we have described the results of MBS similarly where possible.

There are several excellent studies that have reported the weight loss outcomes of MBS in adolescents. The ongoing Teen Longitudinal Assessment of Bariatric Surgery (Teen-LABS) involves a prospective multisite observational approach following a cohort of 242 individuals who were enrolled from 2007 to 2011 with AGB in 14, LSG in 67 LRYGB in 161 [43]. The mean age was 17 ± 1.6 years and mean preoperative BMI was 53. At 3 years, mean weight decreased by 26–28% (95% CI, 25–29) with nearly similar results for LSG and LRYGB.

In 2022, Cruz-Munoz et al. documented long-term follow-up in 96 patients for 10–18 years after MBS [46]. Median pre-MBS BMI was 44.7 kg/m2 (SD 6.5), and mean total body weight decreased by 31.3% (interquartile range (IQR) 20.0–38.9%). Similarly, a 2023 systematic review of long-term studies (more than 5 years) of 29 studies with 4970 participants between 12 and 21 years revealed a mean BMI decline of 13.09 kg/m2 (95% CI 11.75–14.430) from a preoperative BMI range of 38.9 to 58.5 kg/m2 [47••]. Percentage BMI loss was approximately 22–34%.

The studies quoted above reported outcomes from a mix of procedures (LSG and LRYGB). In terms of LSG alone, several studies have shown excellent outcomes with more than 90% of adolescent patients exhibiting 22–30% weight loss at the 1-year mark [48,49,50]. Goldernshluger et al. reported greater than 30% weight loss at the 10-year mark from LSG [51]. Finally, a 2023 systematic review and meta-analysis of LSG alone for adolescents evaluated a total of 2171 patients across 37 studies. Total BMI loss was 17.81 kg/m2 (30–40% loss) across the studies at the 3-year mark (preoperative BMI 38.5 ± 3.7 to 52.1 ± 9.8 kg/m2) [52••].

Two additional issues need to be highlighted in terms of the short- and long-term outcomes after MBS in adolescents. First is the very variable follow-up reported by most studies (3–36 + months), as seen in Table 1, which limits most outcome data. Second is the limited data published detailing either insufficient weight loss or weight regain in adolescents after MBS. There are no standard definitions that exist for adults or adolescents. Limited adult data reveals weight regain between 5 and 20% with greater regain with time, but non-standard definitions across papers make any true assessment incomplete [53].

Table 1 BMI loss outcomes post metabolic and bariatric surgery in adolescents and teenagers
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Comorbidity Improvement

Directly related to weight loss, MBS results in significant improvement in comorbid conditions. These include metabolic syndrome, diabetes, hypertension, and sleep apnea. At 3 years, TEEN-LABS participants had 95% (95% CI, 85–100) remission of type 2 diabetes (T2DM), 66% (95% CI, 57–74) for dyslipidemia, 74% (95% CI, 64–84) for elevated blood pressure, 76% (95% CI, 56–97) for prediabetes, and 86% (95% CI, 72–100) for abnormal kidney function [43].

Wu et al. summarized comorbid condition improvement in a meta-analysis covering 4970 adolescent participants in 29 studies [47••]. Remission rates for T2DM ranged from 44.9 to 100% (19/29 reporting) with a pooled analysis remission rate of 90% (95% CI 83.2–95.6). Dyslipidemia remission rates ranged from 14.3 to 100% (pooled rate of 76.6% (95% CI 62–88.9) 17/29 studies). Hypertension remission rates ranged from 46.7 to 100% (pooled rate 80.7% (95% CI 71.5–88.8 19/29 studies). Limited data were available for obstructive sleep apnea (OSA) and asthma, yet the pooled analysis indicated remission rates of 80.8% (95% CI 36.4–100) for OSA and 92.5% (95% CI 48.5–100) for asthma.

Al-Mohaidly et al. also reported comorbid remission frequencies following LSG in their meta-analysis. Notably, remission rates for hypertension and T2DM ranged from 50–100%, prediabetes from 44–100%, OSA ranged from 36–100%, dyslipidemia ranged from 0–100%, and asthma ranged from 33–100% [52••].

Significant improvements in obesity-related medical conditions are seen after MBS in the adolescent and teenage population. There is strong evidence to suggest that these improvements occur at a higher rate and earlier in this age group [63, 64]. Based on the success of MBS in this age group both in terms of weight loss and improvement of comorbid conditions, guidelines on the use of MBS have recently been changed as described below.

There is some evidence to support the use of MBS earlier in life. Herdes et al. summarized the advantages of earlier referral for MBS in children and adolescents. These include higher likelihood of achieving normalization of BMI, greater total weight loss, improved rates of comorbidity resolution and potential reduction of long-term damage from chronic illness, and finally significant improvements in quality of life and psychosocial stressors. These advantages are associated with lower complication than adults [65•]. Thus, most guidelines now recommend early referral to a multidisciplinary pediatric-focused MBS program.

Complications After Metabolic and Bariatric Surgery

Complications can manifest in both the short (< 30 days) and long term after MBS. TEEN-LABS reported a short-term major complication rate of 7.9% and a 14.9% minor complication rate [66]. The most common major and minor complications were reoperation (2.8%) and urinary tract events (2.5%), respectively.

The Metabolic and Bariatric Surgery Accreditation and Quality Improvement Program (MBSAQIP) database reported a readmission rate of 3.5%, reoperation rate of 1.1%, and complications of 1.2% from their 4051-person cohort [67]. The safety profile and complication rates were similar to those reported in a prospective randomized controlled trial conducted on LRYGB and LSG in the adult population [68].

Long-term complications include gastro-esophageal reflux disease (GERD) (12.7%), symptomatic cholelithiasis (5–12%), and nutritional deficiencies [50, 69, 37]. Iron and B12 deficiency were the most common, specifically in the LRYGB group at 71% and 12%, respectively. These findings were supported by previous studies which reported similar rates of nutritional deficiencies [44].

In their meta-analysis of adolescents limited to LSG, Al-Mohaidly et al. reported GERD as the most common complication ranging from approximately 3–21% [52••]. Other complications included gastrointestinal complaints at 1–8.5%, pulmonary issues at 1.5–5%, leaks and fistulas at 1.6–3.4%, stenosis at 1.5–3.3%, surgical site infection at 1.1–3%, and hernias at 1.5–2.4% approximately. As with all meta-analysis, the authors are limited by their included reports.

Although LRYGB and LSG have both been used in adolescents, LSG is safer. When directly comparing outcomes using MBSAQIP (3571 patients), LRYGB had significantly increased rates of major complications within the first 30 days 4.55% versus 1.34% (P < 0.001) in the unmatched cohort and 4.57% versus 0.91%, P < 0.001 in the propensity-score matched cohort as compared to LSG [70••]. An additional review of 21,592 patients reported higher rates of readmission (6.3% vs. 3.0%), reoperation (2.1% vs. 0.8%), and serious complications (5.5% vs. 1.8%) for RYGB as compared to sleeve gastrectomy [71]. As noted previously, LSG has become the procedure of choice in adults and adolescents due to its better safety profile.

Surgical Versus Non-surgical Management of Obesity in Children

Limited studies have compared lifestyle, pharmacologic, and surgical management strategies for adolescents and teenagers. One RCT, the Adolescent Morbid Obesity Surgery 2 (AMOS2) trial reported a mean BMI reduction of 12.6 kg/m2 in 13–16-year-olds who underwent MBS versus 0.2 kg/m2 in those who received intensive non-surgical therapy [45•]. Most other comparative studies are cohort studies or secondary analyses of previously performed studies. As an example, a recent publication showed that in a cohort analysis of patients over 2 years, MBS clearly resulted in weight loss with co-morbid improvement while those treated with standard recommendations gained weight [50]. Inge et al. showed that MBS was associated with better glycemic control, weight loss, and comorbid condition improvement compared to standard medical therapy [72]. Similar studies exist comparing surgical therapy to standard therapy for kidney disease and cardiovascular disease improvement with similar results favoring MBS [73, 74].

Pharmacologic agents have changed the landscape of obesity management in the last decade. There are no direct comparisons between the newer GLP-1 agents and MBS but some systematic reviews and meta-analysis try to fill in the gaps. Sarma et al. showed that MBS had the best reductions in weight but the groups had similar glycemic control [75]. It is important to note that no such data exists for adolescents.

In 2019 and then in 2023, the American Academy of Pediatrics (AAP) developed guidelines for the evaluation and treatment of obesity in pediatric patients [76, 77••]. These guidelines incorporate the latest and best evidence available to develop their key action statements (Table 2). These statements incorporate diagnostic criteria and comorbid condition identification and intervention. Included is the use of pharmacotherapeutic agents in adolescents 12 and older with obesity and MBS for those 13 and older with severe obesity (≥ 120% of the 95th percentile for age and sex). All children with obesity should immediately incorporate intensive behavior and lifestyle changes using a patient and family-centered approach. Delaying treatment from a “watchful waiting” approach is not supported by evidence and therefore not an option in the guidelines. These AAP guidelines are also supported by the latest 2022 ASMBS guidelines [78••].

Table 2 AAP key action statements summary [77••]
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Current Issues in the Surgical Management of Obesity in Teenagers and Adolescents

Utilization of MBS for adolescents with class II and III obesity is very low at 1.81 procedures per 1000 affected individuals versus 5.56 per 1000 adults between 2015 and 2018 ([79], pp2015-2018). The 2019 AAP guidance may have increased procedure rates between 2020 and 2021 by 19% but the 2023 AAP guideline impact is yet to be ascertained [80]. It is clear, however, that the total number of procedures being performed is still stubbornly low, with less than 2000 procedures performed annually in teenagers and adolescents [81,82,83]. Multiple data sources, including Healthcare Cost and Utilization Project (HCUP) Kids’ Inpatient Database, the National Inpatient Sample (NIS), and Medicaid, confirm this number. In fact, children on Medicaid seem to have the lowest number of procedures performed. The reasons for the limited utilization of MBS in children may include:

  1. 1.

    Access and insurance: The availability of a local or regional comprehensive multidisciplinary pediatric metabolic and bariatric surgery center within reachable distance limits access for families

  2. 2.

    Insurance coverage: Up to 36% of patients whose insurance program covers MBS are denied coverage on their first authorization [82]. More patients with private insurance undergo MBS and most private insurance companies have inclusion and exclusion criteria that rely on the American Society for Metabolic and Bariatric Surgery (ASMBS) recommendations from 2012 [84, 85]. These outdated recommendations use tanner stages, skeletal maturity, and mandatory medical management programs before approving MBS. These barriers have been removed by the latest ASMBS guidelines in 2018 and 2022, but these changes have not been updated by insurance companies [86, 87]

  3. 3.

    Disparities: Although black and Hispanic children have higher rates of obesity, MBS is performed in higher rates in whites [88]

  4. 4.

    Knowledge and stigma: Families, patients, and referring providers have significant knowledge gaps and are concerned about the social implications of undergoing MBS [89]

Conclusion

Metabolic and bariatric surgery (MBS) is effective in children and improves metabolic health while simultaneously leading to significant weight loss in a majority of patients [43, 47, 52, 69, 71]. Pharmacologic agents primarily GLP-1 and GIP agents have shown promising results in the last 5 years. There are significant limitations in the studies which make direct comparison to MBS difficult. These limitations include lower mean BMI of the patients treated compared to MBS studies, significant adverse reactions, and high rates of cessation. In addition, long-term outcomes are unknown, insurance coverage is limited, and cessation of the agents leads to weight regain.

MBS-associated improvements persist over the long term although there is some weight regain similar to adults but not as well studied [53]. MBS is recommended for children struggling with severe obesity per the AAP guidelines. Earlier referral to loco-regional multidisciplinary pediatric centers leads to improved outcomes. Expectations and complications should be clearly discussed with families.

Based on the best available data, we present our proposed algorithm for the treatment of obesity in children that incorporates medical and surgical therapies in a step-wise fashion (Fig. 1).

Fig. 1
figure 1

Pediatric obesity management algorithm. BMI, body mass index; GLP1, glucagon-like peptide 1; GIP, gastric inhibitory polypeptide; WL, weight loss; WR, weight regain. Note: GLP-1 and GIP agents are proposed in our algorithm; however, we do not completely understand their role before or after surgery in adolescents

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