Proposal of an Obesity Classification Based on Weight History (PDF)

consensus Proposal of an obesity classification based on weight history: an official document by the Brazilian Society of Endocrinology and Metabolism (SBEM) and the Brazilian Socie...

consensus Proposal of an obesity classification based on weight history: an official document by the Brazilian Society of Endocrinology and Metabolism (SBEM) and the Brazilian Society for the Study of Obesity and Metabolic Syndrome (ABESO) Bruno Halpern1 1 Centro de Obesidade, Hospital https://orcid.org/0000-0003-0973-5065 9 de Julho, São Paulo, SP, Brasil 2 Grupo de Obesidade e Síndrome Marcio C. Mancini2 https://orcid.org/0000-0003-1278-0406 Metabólica, Departamento de Endocrinologia e Metabolismo, Maria Edna de Melo2 Universidade de São Paulo, https://orcid.org/0000-0002-1216-7532 São Paulo, SP, Brasil Rodrigo N. Lamounier3 3 Centro de Diabetes https://orcid.org/0000-0001-7432-9085 de Belo Horizonte, Belo Horizonte, MG, Brasil Rodrigo O. Moreira4 4 Instituto Estadual de Diabetes e https://orcid.org/0000-0003-1561-2926 Endocrinologia Luiz Capriglione, Mario K. Carra5 Rio de Janeiro, RJ, Brasil https://orcid.org/0000-0001-7238-3280 5 Grupo de Diabetes, Departamento de Endocrinologia, Universidade de Theodore K. Kyle6 São Paulo, São Paulo, SP, Brasil https://orcid.org/0000-0003-1119-5854 6 ConscienHealth, Cintia Cercato2,7 Pittsburgh, PA, USA https://orcid.org/0000-0002-6181-4951 7 Presidente Associação Brasileira para o Estudo da Obesidade e Cesar Luiz Boguszewski8,9 https://orcid.org/0000-0001-7285-7941 Síndrome Metabólica (ABESO), São Paulo, SP, Brasil 8 Serviço de Endocrinologia e Metabologia (SEMPR), ABSTRACT Departamento de Medicina Obesity is a chronic disease associated with impaired physical and mental health. A widespread view Interna, Universidade Federal in the treatment of obesity is that the goal is to normalize the individual’s body mass index (BMI). do Paraná, Curitiba, PR, Brasil However, a modest weight loss (usually above 5%) is already associated with clinical improvement, 9 Presidente da Sociedade Brasileira de Endocrinologia e Metabolismo while weight losses of 10%-15% bring even further benefits, independent from the final BMI. The (SBEM), São Paulo, SP, Brasil percentage of weight reduction is accepted as a treatment goal since a greater decrease in weight is frequently difficult to achieve due to metabolic adaptation along with environmental and lifestyle factors. In this document, the Brazilian Society of Endocrinology and Metabolism (SBEM) and the Brazilian Society for the Study of Obesity and Metabolic Syndrome (ABESO) propose a new obesity classification based on the maximum weight attained in life (MWAL). In this classification, individuals Correspondence to: Bruno Halpern losing a specific proportion of weight are classified as having “reduced” or “controlled” obesity. This Rua Alves Guimarães, 462, simple classification – which is not intended to replace others but to serve as an adjuvant tool – could CJ 72/73, Pinheiros help disseminate the concept of clinical benefits derived from modest weight loss, allowing individuals 05410-000 – São Paulo, SP, Brasil [email protected] with obesity and their health care professionals to focus on strategies for weight maintenance instead of further weight reduction. In future studies, this proposed classification can also be an important Received on Dec/8/2021 tool to evaluate possible differences in therapeutic outcomes between individuals with similar BMIs Accepted on Mar/2/2022 but different weight trajectories. DOI: 10.20945/2359-3997000000465 Copyright© AE&M all rights reserved. Arch Endocrinol Metab. 1  Obesity classification based on weight history INTRODUCTION attained in life (MWAL, or highest-ever weight) and O besity is a chronic and recurrent disease associated the percentage of weight loss achieved to guide clinical with several complications, which in turn cause management and individual decisions. This concept and aggravate other acute and chronic diseases could also be useful in clinical trials since individuals and reduce life expectancy (1-3). Although highly with obesity with different weight trajectories can stigmatized and perceived by many as a “lifestyle have different outcomes (6,23,24). This proposed choice” easily treatable by changes in behavior, obesity classification can also help further disseminate the is instead associated with considerably high rates of simple but underappreciated concept of health benefits treatment failure and a progressive course across life from clinically achievable weight loss and highlight (3,4). Obesity has a complex physiopathology, in which the importance of obtaining an accurate history of the attempts to lose weight are counterbalanced by reduced individual’s weight trajectory during evaluation and energy expenditure and increased hunger and desire management of obesity and related disorders (25). to eat mediated by the hypothalamus and brainstem, Importantly, the aim of this proposed classification is driving weight regain (5-8). The observation of these not to replace traditional and consolidated classifications mechanisms led to the hypothesis that the body must but rather be an adjuvant tool to guide clinical treatment defend a weight “set point.” Despite many knowledge and help interpret the findings of clinical research and gaps on how this set point changes upward throughout interventions in the field of obesity. This classification life and whether the set point would be more a range can be further improved in the future and be validated than a fixed value (5,9), clinical evidence suggests that in observational and intervention studies. Once attempts to lose weight are generally counterbalanced published, this classification will be tested in different by a trend toward weight regain after a weight-loss clinical scenarios to evaluate its usefulness before its intervention (3,5). Moreover, there is no evidence that widespread use. this set point resets downward; instead, the available literature shows that the metabolic adaptation remains Classifications of obesity the same or decreases in the long term (10-12). “Resolution” of obesity is rarely achieved with Obesity, recognized by several entities as a chronic clinical treatment. Indeed, a substantial number of and progressive disease, has been defined by the World studies have clearly shown that clinically achievable Health Organization as an “excess fat accumulation weight loss reduces health risks independent from the that impairs health” (26,27). Excess fat accumulation final weight (13-15). Several guidelines worldwide as a concept seems simple, but its definition is not recommend a weight loss of 5%-10% (3,16-19), but no straightforward. The BMI, calculated as weight divided guideline, as far as we know, has proposed to identify by squared height, is the most common and accepted and classify individuals who had lost weight in the past tool to diagnose overweight or obesity but has and were able to maintain the loss. This is a critical several caveats and large interindividual risk variability issue, considering that clinical practitioners usually (3,28,29). Although useful for epidemiological data, recommend further weight loss (often clinically difficult BMI often fails to determine the individual’s risks to achieve) to individuals who remain with increased in a clinical setting (3,30-32). Differences in body BMI after weight loss. These individuals are considered composition (fat mass and fat-free mass) and fat “high risk” by health insurance companies, perceive distribution are some of the factors that reduce the themselves as having increased risk for several diseases, diagnostic accuracy of the BMI in assessing health risks and do not focus on weight maintenance, increasing at individual levels (3,18,28,30). the odds of weight regain and yo-yo dieting (4,20-22). Waist circumference (WC) has been proposed as a In this document, the Brazilian Society of complementary tool for evaluation of risks associated Endocrinology and Metabolism (Sociedade Brasileira with obesity, and its importance as a marker of Copyright© AE&M all rights reserved. de Endocrinologia e Metabologia – SBEM) and the cardiometabolic health independent from BMI has been Brazilian Association for the Study of Obesity and shown in many studies (29,31,33-35). Increased WC Metabolic Syndrome (Associação Brasileira de Estudo is an undeniably excellent marker of cardiometabolic da Obesidade e Síndrome Metabólica – ABESO) propose status in individuals with normal weight or overweight, a classification for obesity using the maximum weight but in individuals with higher BMI, WC measurements 2 Arch Endocrinol Metab.  Obesity classification based on weight history are less useful in identifying whether the excess fat Some authors have suggested that a weight loss of occurs predominantly due to subcutaneous or visceral 3% can be associated with a decreased likelihood of abdominal fat (31,35,36). High interindividual and complications from infectious diseases, including intraindividual variability in WC measurement is COVID-19 (50,51). When above 5%, the weight loss another limitation of this tool (29,37,38). has significant effects on metabolic markers (such as Other available means to evaluate body composition HDL-cholesterol) (52), depression, joint pain, and and distribution that can be useful in clinical practice sexual function (14,53-56). A weight loss goal of 7% or research include bioimpedance analysis, dual-energy has been associated with a lower risk of type 2 diabetes x-ray absorptiometry, and computed tomography in the Diabetes Prevention Program (DPP) trial, in scanning, although these tools are rarely used for which each kilogram lost was associated with a nearly diagnosis or management of obesity (39-41). 16% reduction in diabetes risk (48,49). Weight losses Considering the pandemic nature of obesity and above 10% have important effects on steatohepatitis the fact that BMI is not a good predictor of individual (14,57,58). A post hoc analysis of the LOOK AHEAD health status, the strategy of defining a subclassification trial evaluating intensive lifestyle modification over 9 for obesity that could provide priority treatment access years in individuals with type 2 diabetes has found that for high-risk individuals seems well-founded (32,42). treatment responders with a 10% weight loss had a 21% Several ways to classify obesity as metabolically reduction in the primary outcome of cardiovascular “healthy” or “unhealthy” have been proposed. events (59). Additionally, an 11% weight loss has However, widespread use of this classification has been associated with a nearly 23% reduction in intra- been curbed by controversies surrounding the criteria abdominal adipose tissue, confirming that voluntary defining metabolic health, cutoff levels, and inclusion weight loss has a disproportionally positive effect of more complex measures of disease (such as insulin on ectopic fat deposition, which is associated with resistance or hepatic fat) (43,44). atherosclerosis (36,60). A classification of obesity based on the presence of The DiRECT trial evaluated diabetes remission in comorbidities and disabilities as a staging system (similar individuals with a recent diagnosis of type 2 diabetes and reported that weight losses of 10 and 15 kg (about to the classifications used in oncology) has also been 10% and 15%, respectively, of the individuals’ initial proposed, for example, the Edmonton Obesity Staging weight) were associated with rates of diabetes remission System (18,32,45). This system is simple and useful of 57% and 86%, respectively (61). A similar study to evaluate the risks and benefits of different obesity from the same trial in which the mean weight loss was treatments but has some limitations as, for example, 14% showed normalization of liver fat in individuals the parameter of “psychological burden” included in achieving diabetes remission and a reduction in the the classification cannot be objectively defined. Some predicted cardiovascular risk score (QRISK) from 23% professional associations have suggested that the term to 7% (62,63). A recent weight-matched study evaluated “obesity” should be changed and that the classification individuals undergoing Roux-en-Y gastric bypass or of excess fat impairing health should receive different diet-induced weight loss who presented a mean weight terminologies – such as adiposopathy or adiposity-based loss of 18% and confirmed that the metabolic benefits chronic disease (ABCD) – but these recommendations were induced mainly by weight loss, suggesting have only been used in limited settings (32,46). dramatic positive effects with the achieved weight loss, even though the final BMI in both groups remained Weight loss of 5%, 10%, 15% or more and above 35 kg/m² (64). The same group that conducted reduced risks the study has also demonstrated clearly reduced Even modest weight losses are associated with health inflammation with weight loss above 16% (60). This and quality of life benefits (14). Several guidelines is the same proportion of weight loss achieved after 10 Copyright© AE&M all rights reserved. on the clinical treatment of obesity indicate that years by individuals in the vertical-banded gastroplasty weight losses of 5%-10% are clinically significant and arm in the Swedish Obese Subjects (SOS) study; these recommend this range as a treatment target (4,16- individuals comprised 70% of the entire cohort and were 19). Weight losses of 3% or less are associated with not expected to present metabolic effects beyond the benefits on fertility and glucose levels (14,47-49). weight loss, due to the nature of the procedure (14,65). Arch Endocrinol Metab. 3  Obesity classification based on weight history Even though the SOS study was not powered to This value should be considered for the primary compare bariatric procedures, the overall cohort had diagnosis based on the original classification of obesity a substantial decrease in overall mortality and a life (Class I, 30.0-34.9 kg/m²; Class II, 35.0-39.9 kg/ expectancy increase lasting at least 24 years (13,66). m²) followed by the terms “unchanged” (if close to These individuals had a final BMI of approximately 35 the MWAL), “reduced” (if 5%-10% of weight loss is kg/m², indicating that two individuals with the same achieved), or “controlled” (if at least 10% of weight weight but different weight trajectories can exhibit loss is achieved). The percentage of weight loss (by 5% entirely different overall risks (63). Questions remain decrements) should also be identified. For individuals regarding the existence of a specific threshold below with BMI values between 40-50 kg/m², we propose which the risks decrease or whether progressive weight that the term “controlled” should be applied if the loss is associated with a proportional decrease in risks. weight loss achieved is above 15%, “reduced” if between Weight losses of 16%-20% or more are rarely achievable 10%-15%, and “unchanged” if less than 10%. Below are in the long term with currently available clinical two examples from Table 2. therapies (66). However, this scenario can potentially In Case 1, a man with a height of 175 cm and an MWAL change with the development of new and more of 118 kg has a BMI of 38.5 kg/m² and Class II obesity efficacious antiobesity drugs (67,68). As such, clinically (unchanged). If he lost 10 kg (8.4% of his maximum achievable weight loss has been clearly recommended weight), he would remain in the Class II obesity category as the goal in obesity treatment, and proposals have but would be considered as having “reduced obesity” in emerged indicating that the achievement of metabolic this newly proposed classification since he could derive health in individuals with obesity is the “low-hanging clinical benefits from his weight loss. Had only his BMI fruit” for treatment (69). A classification for individuals values been considered, no change would have occurred, who are able to achieve such goals is imperative. and his weight loss would be considered insufficient or his treatment a failure. If he lost 15 kg (12.7% of Proposed classification based on the weight his MWAL), he would still be categorized as having trajectory and the maximum weight achieved in life Class II obesity based on his MWAL and would be considered “controlled” based on his weight loss of This new classification (Table 1), deliberated by a working 12.7%. Thus, the decision to lose more weight should group from both Brazilian medical societies, identify be analyzed individually based on the patients’ overall individuals based on weight trajectory during clinical health and metabolic status (and not solely on BMI treatments for obesity (including non-pharmacological values). Should the patient lose even more weight (20 and pharmacological treatments, as well as therapies kg), he would very likely show clinical improvement using non-surgical devices) and is intended for adults but would remain in the same category in the original aged 18 to 65 years and with BMI values between classification. In the new proposed classification, he 30 and 50 kg/m². The classification does not apply would be considered as having Class II obesity (15% to individuals with end-stage diseases due to lack of controlled). benefits from weight loss in these circumstances. It In Case 2, a woman with a height of 156 cm and also does not apply to individuals using corticosteroids an MWAL of 100 kg has a BMI of 41 kg/m² and Class chronically or intermittently or with endogenously III obesity. If she lost 6 kg, she would be reclassified as increased cortisol levels due to Cushing’s syndrome, having Class II obesity based on her BMI but would still or those using other short-term drugs leading to be considered to have Class III obesity (unchanged) weight gain. We acknowledge that many proposals for according to the proposed classification since she reclassification of obesity advocate against using BMI as did not achieve a minimum of 10% to be considered the only diagnostic criteria, but BMI is the single most “reduced.” If she lost more than 10 kg (11 kg in common starting point. Therefore, we incorporated Scenario 2C in Table 2), she would be categorized as Copyright© AE&M all rights reserved. BMI into this proposed classification to avoid confusion having Class III obesity (10% reduced), and if she lost or complexities at the moment. 18 kg, she would still be categorized as having Class III In this proposed classification, the patients obesity (15% controlled) in the proposed classification. should be asked in their first visit about their MWAL If an individual lost a substantial amount of weight (excluding weight recorded during pregnancy). (as in Scenarios 1D or 2D) and is not able to lose more 4 Arch Endocrinol Metab.  Obesity classification based on weight history Table 1. Proposed classification of “reduced” and “controlled” obesity based on maximum body mass index (BMI) Maximum BMI Unchanged* Reduced* Controlled* 30-40 kg/m² 10% 40-50 kg/m² 15% Table 2. Newly proposed classification based on two clinical cases Case 1: A 55-year-old man with a maximum weight achieved in life (MWAL) 2 years earlier of 118 kg and a height of 175 cm (BMI of 35.9 kg/m²). Percentage of Hypothetical Newly proposed Traditional Weight (kg) BMI (kg/m²) weight loss based scenarios classification classification on MWAL 1A 115 38.5 2.5% Class II obesity (unchanged) Class II obesity 1B 108 35.2 8.4% Class II obesity (5% reduced) Class II obesity 1C 103 33.6 12.7% Class II obesity (10% controlled) Class I obesity 1D 98 32.0 16.9% Class II obesity (15% controlled) Class I obesity Case 2: A 40-year-old woman with an MWAL of 100 kg (6 months earlier) and a height of 156 cm (BMI 41 kgm²). Percentage of Hypothetical Newly proposed Traditional Weight (kg) BMI (kg/m²) weight loss based scenarios classification classification on MWAL 2A 98 41 2% Class III obesity (unchanged) Class III obesity 2B 94 39.1 6% Class III obesity (unchanged) Class II obesity 2C 89 37 11% Class III obesity (10% reduced) Class II obesity 2D 82 34.1 18% Class III obesity (15% controlled) Class I obesity weight, his or her goal would be to maintain weight differentiation of insufficient weight loss and long-term instead of losing more weight, which would probably weight regain after the bariatric procedure. happen had only the new BMI been considered. For regions or ethnic groups defining criteria for Special situations overweight and obesity by different BMI cutoff values, Pregnancy and lactation the classification can follow the specific local and ethnic Weight gain is expected to occur during pregnancy. criteria. This proposed classification can also help Although some women gain more weight than expected individuals understand that obesity is a chronic disease and struggle to lose the gained weight in the postpartum and, regardless of their current weight status, their period, the weight generally decreases naturally during biology is driven toward weight regain. It also includes and after lactation (70-73). The maximum weight the MWAL as important information to be collected in achieved in pregnancy should be accurately written in the patient’s medical history. the patient’s medical history but should not be used for Of note, this document is not intended to the classification proposed in this document. Instead, determine the criteria for success after bariatric the MWAL should consider nonpregnant conditions. procedures, and the proposed terms “reduced” and If the MWAL was achieved after pregnancy, the stable “controlled” are applicable to the success of clinical weight reached after the end of the lactation should be but not surgical treatments. Still, we recognize that considered as the MWAL. the idea of classifying obesity based on MWAL and Copyright© AE&M all rights reserved. percentage of achieved weight loss could be useful in Involuntary weight loss individuals undergoing bariatric surgery and be applied Several life-threatening diseases lead to involuntary to guide clinical decisions. However, some adjustments weight loss and cachexia; these conditions are the to the classification would be necessary, including the source of important bias in epidemiological studies Arch Endocrinol Metab. 5  Obesity classification based on weight history evaluating the relationship between weight loss and previously in this document may apply to this younger health status (25,74-76). Since long-term voluntary population (92,93). A classification dedicated to weight loss and maintenance are hard to achieve, children and adolescents with obesity should consider most individuals losing substantial weight in large the social burden and stigma of this diagnosis in young observational datasets are likely to be those with severe individuals. diseases (77,78). If the weight loss achieved clinically is suspected of having occurred involuntarily, the Exogenous or endogenous hypercortisolemia classification proposed in this document should not be Chronic and recurrent use of corticosteroids can lead used, and an investigation of the possible causes for the to weight fluctuations, hindering proper interpretation weight loss is warranted. of the MWAL and identification of the weight as being voluntary or involuntary (94). Cushing’s Individuals with end-stage chronic diseases syndrome, treated or untreated, can also affect This proposed classification does not apply to individuals body weight regulation (95). As such, the proposed with end-stage diseases (e.g., patients with chronic renal classification should not be used in individuals receiving failure undergoing dialysis, heart failure NYHA classes active treatment for Cushing’s syndrome or using III or IV, cirrhosis, or metastatic cancers with reduced corticosteroids intermittently. In individuals with long- overall survival, among others). For individuals with term remission from Cushing’s syndrome or who were these conditions – classified as stage 4 in the Edmonton chronically treated with corticosteroids in the past but Score – palliative measures are more important than are no longer receiving such treatment, the proposed weight loss (45). criteria should be used with caution, and the MWAL should be considered after the treatment period. Older age We chose to limit this new classification to adults Acute and reversible situations that could lead to younger than 65 years. Altered body composition – weight gain particularly loss of lean tissue (mainly muscle mass) Overfeeding studies have shown that the body and increased body fat – become more evident with presents adaptive responses that curb weight gain in age and can have profound metabolic effects (79-81). the long term, such as those observed with caloric With age, BMI values usually stabilize or reduce, but restriction but in the opposite direction. During short- visceral fat and intramyocellular fat increase (79,82). term overfeeding (e.g., occurring during holidays or As such, the diagnosis of obesity based only on body vacations), any weight gain is at least partially reversible weight is imperfect, so body composition data should after the individual returns to routine daily life (96-98). be considered in the diagnosis; this has resulted in Therefore, if the MWAL was achieved during a very different cutoff values for healthy BMI proposed for short period of time, the MWAL should be defined this age group (83-85). At the same time, the possibility as the maximum stable weight that occurred during a of concomitant diseases leading to involuntary weight longer period, which has been arbitrarily defined in this loss increases with age (76,80,86). Still, individuals document as at least 3 consecutive months. Similarly, with obesity losing weight voluntarily can derive if the individual gained weight using obesogenic clinical benefits, but caution regarding sarcopenia and medications – such as antidepressants and antipsychotics osteoporosis associated with the weight loss should be – for a very short period, the weight assessed at that exercised (89,87-90). moment should not be considered as the MWAL (99) since weight loss is common after these drugs are Children and adolescents withdrawn. However, if these drugs are used during a This new classification is not intended for individuals longer period (e.g., more than 3 months) and have a Copyright© AE&M all rights reserved. younger than 18 years. In this population, obesity substantial impact on the individual’s weight, and if the should be diagnosed based on BMI Z-scores according MWAL was reached in this setting, this MWAL should to age, weight, and height (91). Children and be considered even if the drugs are withdrawn later, adolescents with obesity have higher odds of becoming since chronic use of these medications is a risk factor for adults with obesity, and many of the concepts discussed obesity (100,101). 6 Arch Endocrinol Metab.  Obesity classification based on weight history Use of antidiabetic agents leading to weight gain proposed for these individuals since it focuses on Type 2 diabetes is intrinsically related to weight gain metabolic abnormalities rather than weight, but and obesity. In our view, the concept of “controlled” several controversies remain in terms of the criteria obesity proposed in this new classification is extremely that should be used to consider them as metabolically useful in patients with this disease, particularly in the unhealthy (46). As described for individuals who first 6-8 years after diagnosis, when significant weight are overweight, the proposed classification does not loss can change the natural course of the disease apply for individuals who have normal weight but are metabolically unhealthy. and even lead to diabetes remission (52,61,63,66). However, many antidiabetic agents are associated with Class IV and V obesity (body mass index above weight gain (e.g., insulin, sulfonylureas, glinides, and 50 kg/m2) thiazolidinediones) (99,102,103). If these medications are used chronically, no changes should be made to Limited quality data exist on weight loss outcomes the classification, and the concept of “controlled” in individuals with BMI above 50 kg/m², and it is obesity can support the use of antidiabetic agents with unclear whether the weight loss percentages used for a more favorable effect on weight (102). Weight gained individuals with BMI 30-50 kg/m² should be applied to after short-term intensification of insulin (e.g., during consider these individuals “controlled.” Consequently, hospitalization, acute illness, or related to glucotoxicity) we decided against proposing specific weight loss that is further discontinued or reduced in dose should thresholds for individuals with BMI values above 50 not be considered the MWAL. kg/m², for whom the burden of obesity is extreme and clinical treatments have limited benefits (109,110). Smoking cessation and relapse Strengths and limitations Smoking cessation is associated with weight gain in most individuals (104-106). The MWAL can be considered The main strength of this simple new classification is the when recorded after smoking cessation, but if smoking emphasis on the achievement of weight loss goals with relapses and the individual loses weight, this “tobacco- clinical treatment, as defined in several guidelines. This induced” weight loss should be seen as involuntary proposed classification yields a more comprehensive and not considered to classify the individual as having view of the individual’s weight status and establishes “reduced” or “controlled” obesity. future objectives for patients and health care providers. We believe that this simple and ready-to-use classification Overweight individuals can help reduce the stigma of clinical obesity treatment, improve long-term adherence to obesity therapy, and Overweight is associated with increased health risks. facilitate the understanding that obesity is a chronic and Several guidelines suggest weight loss for individuals recurrent disease. The only information that must be with overweight, particularly when associated with reliably obtained is the individual’s MWAL, which has comorbidities (1,16-19). We believe that the idea previously been proposed as important information in of “reduced” and “controlled” overweight is valid the clinical setting (23,25,111). in individuals with overweight the same way that it The stigma of obesity – unfortunately very common is applied for obesity, particularly in patients with in health care and across society – is associated with comorbidities. However, we emphasize that this poorer health outcomes and further weight gain proposed classification applies to individuals with (112,113). With this proposed classification being obesity defined as a BMI above 30 kg/m2. implemented, future studies can be performed to evaluate its impact on weight stigma. However, we Metabolically unhealthy, normal-weight individuals believe that this impact will be positive since the Copyright© AE&M all rights reserved. Even with a “normal” BMI, some individuals have classification will enable health care providers to metabolic abnormalities related to excess adiposity understand – even if partially – the complex regulation with abnormal distribution and probably benefit of body weight and the benefits of modest weight losses. from losing weight below an individual threshold This proposed classification can also help patients and (107,108). The ABCD classification has been health care providers in discussing more realistic goals Arch Endocrinol Metab. 7  Obesity classification based on weight history and guide health care professionals not involved in the used as a simple, objective, and continuous target of management of obesity in referring patients for proper disease control in obesity (15). care, using it as an adjuvant to other measurements, This proposed classification also has several classifications, and clinical findings. Before widespread limitations, as listed below: implementation of this classification, we plan to conduct First, this classification relies on self-reported questionnaire studies to inquire individuals living with MWAL, which can be subjected to recall bias obesity whether they believe this classification could (119,120). Also, it has been suggested that the weight help treat obesity and reduce the stigma of the disease. set point may be a range instead of a fixed value. Future studies are required to validate this Moreover, periods of transient overfeeding may lead classification for risk stratification and prediction to acute and (at least partially) reversible weight gain of clinical outcomes. Other classifications (e.g., the (9,97,121). Therefore, it is advisable to consider as the Edmonton Obesity Staging System) were first proposed MWAL a stable weight maintained for more than 3 and then validated in epidemiological studies. We months, although we acknowledge that this period is believe the same can be done with our classification arbitrary. Development of biomarkers for use as more (42,45,114). This proposed classification could also objective parameters of reduced obesity status would be useful in interventional obesity studies. Generally, be desirable. Nonetheless, the spread of the concept clinical trials do not include these simple data that might of MWAL as an important measuring tool could help influence outcomes (25). Individuals near their MWALs people living with obesity and health professionals to are expected to lose more weight in response to an value this information and reduce the bias of recalling intervention compared with individuals with reduced previous weight. or controlled obesity, who are expected to lose less Second, the proposed classification has the known additional weight (6,25). If a trial enrolls a large number limitations of the use of BMI in clinical practice. As of individuals with reduced or controlled obesity, the mentioned before, BMI values can be a poor marker of impact of the intervention may be underestimated. individual health, and variations in body composition The same applies to experimental studies since cerebral and distribution can impact their interpretation (28). or hormonal responses to overfeeding, underfeeding, However, this classification relies on more than just or different food stimulation differ according to the BMI, as it also considers the weight history. individual’s weight-reduced status, which can lead to Third, the classification adopts only weight loss biased interpretations of the results (115). as a marker of obesity control. The goal of obesity The concept of controlled disease is not new. treatment is to improve health and quality of life, and Indeed, this concept is widely used in individuals similar weight losses can have a diverse clinical impact with diabetes. Individuals with diabetes with glycated on different individuals depending on baseline health hemoglobin (HbA1c) levels lower than 7.0% can be status and overall individual conditions (3,18). We considered “well controlled” despite this level being acknowledge that for an individual with obesity to above normal (116). This definition of optimal control be considered “controlled,” the weight loss achieved is based on several observational and randomized would have to provide evident clinical benefits such controlled trials showing that a reduction in HbA1c as improvement in metabolic markers, physical level is associated with improved diabetes outcomes functioning, or mental health. However, we decided (117,118). Compared with diabetes, the evidence against adding clinical markers to the classification at is weaker for obesity due to fewer clinical studies, as the moment to keep it simple for clinicians. Extensive previously discussed, but randomized controlled trials discussions in the literature debate the use of criteria to have shown that a 5%-15% weight loss is associated identify metabolically healthy obesity (44) and whether with reduced morbidity (14,48,49,52-59,61,63). Still this term should even be used (44,122). Additionally, using diabetes as an example of a disease related to it is difficult to objectively measure without using Copyright© AE&M all rights reserved. obesity, evidence shows that weight loss reduces the questionnaires the mechanical and mental health incidence and increases the odds of remission of this benefits of weight loss. Additionally, the impact of disease (48,49,61), but proposals on how to record this weight loss on mental health has not been broadly information in the long term are lacking. As such, the evaluated (123), and any classification based on clinical MWAL and the percentage of weight loss can also be improvement could be subjective and complicate its 8 Arch Endocrinol Metab.  Obesity classification based on weight history implementation. We are aware that an “advanced cannot exclude the possibility that a large proportion classification” considering both the weight loss achieved of the individuals in clinical trials already had (at least and the clinical benefits could be more precise – albeit slightly) a weight reduction and, as such, the benefits less practical – in identifying “controlled” obesity. A from a modest weight loss (e.g., 5%-10%) from the future step could be a combination of this proposed MWAL could have a lower clinical significance. We classification and an improvement in the Edmonton are aware of these limitations, but we believe that this Obesity Staging System (45) (e.g., from EOSS stage 2 classification could help future trials answer questions to stage 1) or an individual change from a well-defined by objectively categorizing individuals into groups classification of metabolically unhealthy obesity to according to their previous weight trajectories. Since metabolically healthy obesity, as proposed by Stefan weight history is rarely recorded in medical charts, this and cols. (69). proposed classification could not be validated before Fourth, this classification is not a guideline, as being implemented. A recent observational study of discussed above. An individual considered to have risk prediction evaluated patients’ weight history based controlled obesity could derive benefits from losing on data from medical records and a follow-up of 6 further weight or be a candidate for bariatric surgery. years. Aligned with our proposal, individuals with more Likewise, individuals with reduced (or unchanged) than 15% of weight loss developed cardiometabolic obesity might not need to lose more weight if they outcomes later than those with less than 7% of weight have a low overall burden from their high BMI. This loss (124). The same authors also found similar results classification is rather intended to provide important regarding osteoarthritis and health care utilization information for discussion with the patient and, as any (125). Nonetheless, no information was provided about other classification, should be considered in the overall MWAL, and their classification was different from ours. context of the patient’s health and long-term goals. A more unified or known definition could facilitate the Fifth, a wide range of individuals were not included research in the field. Another less conclusive example is in this proposed classification due to the reasons a recent prospective cohort study evaluating BMI and pointed out above, but their weight trajectories could prognosis of COVID-19, in which the authors evaluated also be used as a management guide. As such, we see whether prior weight loss was protective against severe the MWAL as almost a “vital sign” to be asked at every COVID-19, but the analysis could not be performed clinical history taking, even if this proposed classification because the weight changes were poorly reported is not applicable to the individual. (126). If the importance of recording weight history Finally, our classification has not been validated in medical charts is not emphasized and the concept and lacks direct evidence showing that a “reduced” or of “reduced” and “controlled” obesity is not widely “controlled” obesity status is associated with reduced known, these issues will probably never be adequately hard outcomes. At present, the evidence is indirect and addressed. Even if this proposed classification is not based on reduced cardiovascular risk factors observed in readily applied before further validation, it still can be mechanistic studies, subanalyses of clinical trials (such useful as a “call for action” for health care professionals as the post hoc analysis of the LOOK AHEAD trial), and to record the patients’ MWAL and understand its after bariatric surgery, in which the magnitude of the usefulness. weight loss is usually higher. The decision of adopting In conclusions, this document proposes a new a weight loss of 15% as the criteria for controlled and relatively simple classification of obesity for adults obesity in individuals with a BMI above 40 kg/m² aged 18-65 years based on the percentage of weight derived mainly from indirect data from the gastric loss from the MWAL and using the terms “reduced” banding and vertical-banded gastroplasty arms of the and “controlled” obesity. This proposed classification SOS study (65). This indirect evidence from surgical intends not to replace other classifications but rather studies does not rule out the possibility of weight- serve as an adjuvant tool. This classification could Copyright© AE&M all rights reserved. independent effects (13,14,59,60,65), and the SOS have practical implications on obesity care and, after study was not powered to evaluate differences between validation in future studies, could be improved with procedures. As such, the evidence for the proposed new data and input, especially if combined with clinical thresholds of “reduced” and “controlled” obesity is markers. Both SBEM and ABESO intend to validate this weak. Since studies have rarely used the MWAL, we classification before it is widely utilized but believe that it Arch Endocrinol Metab. 9  Obesity classification based on weight history could be a very useful tool to help clinical decisions and 15. Halpern B, Mancini MC. Controlled obesity status: a rarely used concept, but with particular importance in the COVID-19 reduce the stigma of obesity. This classification could pandemic and beyond. J Endocrinol Invest. 2021;44(4):877-80. also be useful in future epidemiological, mechanistic, 16. Jensen MD, Ryan DH, Apovian CM, Ard JD, Comuzzie AG, Donato and interventional studies. KA, et al.; American College of Cardiology/American Heart Association Task Force on Practice Guidelines; Obesity Society. Funding statement: the costs of this publication were equally sha- 2013 AHA/ACC/TOS guideline for the management of overweight red by the Brazilian Society of Endocrinology and Metabolism and obesity in adults: a report of the American College of (SBEM) and the Brazilian Society for the Study of Obesity and Cardiology/American Heart Association Task Force on Practice Metabolic Syndrome (ABESO) using their own resources. Guidelines and The Obesity Society. Circulation. 201424;129(25 Suppl 2):S102-38. 17. 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