Exercise training in the management of overweight and obesity in adults: Synthesis of the evidence and recommendations from the European Association for the Study of Obesity Physical Activity Working Group

Summary There is a need for updated practice recommendations on exercise in the management of overweight and obesity in adults. We summarize the evidence provided by a series of seven systematic literature reviews performed by a group of experts from across Europe. The following recommendations with highest strength (Grade A) were derived. For loss in body weight, total fat, visceral fat, intra‐hepatic fat, and for improvement in blood pressure, an exercise training program based on aerobic exercise at moderate intensity is preferentially advised. Expected weight loss is however on average not more than 2 to 3 kg. For preservation of lean mass during weight loss, an exercise training program based on resistance training at moderate‐to‐high intensity is advised. For improvement in insulin sensitivity and for increasing cardiorespiratory fitness, any type of exercise training (aerobic, resistance, and combined aerobic or resistance) or high‐intensity interval training (after thorough assessment of cardiovascular risk and under supervision) can be advised. For increasing muscular fitness, an exercise training program based preferentially on resistance training alone or combined with aerobic training is advised. Other recommendations deal with the beneficial effects of exercise training programs on energy intake and appetite control, bariatric surgery outcomes, and quality of life and psychological outcomes in management of overweight and obesity.


Summary
There is a need for updated practice recommendations on exercise in the management of overweight and obesity in adults. We summarize the evidence provided by a series of seven systematic literature reviews performed by a group of experts from across Europe. The following recommendations with highest strength (Grade A) were derived. For loss in body weight, total fat, visceral fat, intra-hepatic fat, and for improvement in blood pressure, an exercise training program based on aerobic exercise at moderate intensity is preferentially advised. Expected weight loss is however on average not more than 2 to 3 kg. For preservation of lean mass during weight loss, PROSPERO registration number: CRD42019157823. an exercise training program based on resistance training at moderate-to-high intensity is advised. For improvement in insulin sensitivity and for increasing cardiorespiratory fitness, any type of exercise training (aerobic, resistance, and combined aerobic or resistance) or high-intensity interval training (after thorough assessment of cardiovascular risk and under supervision) can be advised. For increasing muscular fitness, an exercise training program based preferentially on resistance training alone or combined with aerobic training is advised. Other recommendations deal with the beneficial effects of exercise training programs on energy intake and appetite control, bariatric surgery outcomes, and quality of life and psychological outcomes in management of overweight and obesity.

| INTRODUCTION
Physical activity is recognized as a "pillar" in the management of overweight and obesity, in parallel with dietary counseling, behavioral support, medication, and, in some instances, bariatric surgery. 1 Physical activity is defined in broad terms as "any bodily movement produced by skeletal muscles that results in energy expenditure." 2 Exercise is viewed as a subcategory of physical activity that is "planned, structured, repeated with a given purpose, to maintain or increase physical fitness" (see Glossary, Table 1). 2 Although the value of physical activity and exercise for maintaining health and preventing noncommunicable diseases is acknowledged as a public health "best buy," 3,4 the role they may have for weight control remains debated both in the scientific 5 and lay literature. 6 Several important reviews and position statements have been issued on the topic of physical activity and exercise regarding management of obesity during the 2000s. [7][8][9] However, there has not been any systematic effort to get an overall update of more recent existing knowledge. Such overview would however be much needed to inform the design of practice guidelines for routine management of overweight and obesity in adults. In particular, there is a need for updated knowledge on the effects of various forms of exercise training programs (e.g., aerobic, resistance, or combined training) on weight loss, body composition changes with weight loss, and weight maintenance after weight loss in adults with overweight and obesity. Moreover, several topics of major importance have not been comprehensively addressed in previous reviews such as the effect of specific exercise training program in persons with overweight and obesity on intrahepatic fat, insulin sensitivity, blood pressure, cardiorespiratory and muscle fitness, eating behavior, hunger and satiety, and quality of life and psychological well-being. To fill these gaps, a working group of European experts was convened in 2019 under the auspices of the European Association for the Study of Obesity (EASO 10 ). EASO is a federation of professional membership associations from 36 countries across Europe and it produces guidelines as a key element of the education about obesity management.

Term Definition
Physical activity Any bodily movement produced by skeletal muscles that requires energy expenditure Exercise training Exercise is a subcategory of physical activity that is planned, structured, repetitive, and purposeful with primary purpose of improving or maintaining physical fitness, physical performance, or health.
Aerobic training Programs based on forms of activities that are intense enough and performed long enough to maintain or improve an individual's cardiorespiratory fitness. Here, "aerobic" refers to moderate-intensity aerobic training. On a scale relative to an individual's personal capacity, moderate-intensity physical activity is usually a 5 or 6 on a scale of 0-10. Based on heart rate, moderate-intensity physical activity is usually defined as 50%-70% of maximal heart rate.
Resistance training Also referred to as "muscle-strengthening activities": programs based on activities that increase skeletal muscle strength, power, endurance, and mass and that involve major muscle groups (legs, back, abdomen, chest, shoulders, and arms). Intensity of resistance training is usually defined according to the one-repetition maximum (1RM). Moderate intensity is usually defined as more than 60% of the 1RM.

High-intensity interval training (HIIT)
Consists of short periods of high-intensity anaerobic exercise, commonly less than 1 min, alternating with short periods of less intense recovery.
Physical fitness A measure of the body's ability to function efficiently and effectively in daily-life activities. Includes cardiorespiratory fitness, muscle strength, balance, and flexibility.

| METHODS
All members of the working group followed the same methods to synthesize the evidence and format the recommendations, with variations as needed to reflect the evidence available in each field. The methodology followed a prespecified development process in three steps: (1) conducting of systematic reviews and meta-analyses (SR-MAs), (2) writing of evidence statements, and (3) designing of recommendations.

| Systematic reviews and meta-analyses
The systematic reviews followed the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines and were registered in the PROSPERO database (registration number CRD42019157823). Seven a priori defined research questions (Q1 to Q7) were addressed in the systematic reviews included in this supplement ( Data were extracted using standardized forms. The effects of exercise were assessed using random-effects meta-analyses (Cochrane

Review Manager 5.3 or Comprehensive Meta-Analysis version 3).
Effect sizes were reported as mean difference, MD, or standardized mean difference, SMD, alongside their 95% confidence intervals (CI) and p values and were categorized as large, medium, small, or negligible. A p value < 0.05 was considered statistically significant.
To assess study quality (good, fair, or poor), we used the tool developed by the National Heart, Lung and Blood Institute (NHLBI, USA) that has been previously used for defining guidelines for the management of obesity. 19 The original assessment forms for SR-MAs, controlled trials, cross-over trials, and single-group interventions were used. Publication bias was assessed by visual inspection of the funnel plots and when the number of included studies was >10, Egger's test and sometimes additional tests were performed (see individual papers for more details).

| Evidence statements
Four to seven evidence statements were defined for each research question. The strength of each evidence statement was rated as high, moderate or low (Table S1) using the tool developed by the NHLBI. 19 The strength of evidence represents the degree of certainty, based on the overall body of evidence, that an effect or association is correct. 19 (Table S2).  Energy intake and appetite 9. Eating behavior Inform persons with overweight or obesity that an exercise training program will not have a substantial impact on energy intake but rather may improve eating behaviors. Inform that expected additional weight and fat loss is on average not more than 2 to 3 kg.

| IMPLICATIONS FOR CLINICAL PRACTICE
Based on the evidence gathered through our systematic search and analysis of the literature on exercise in the management of overweight and obesity in adults, some implications for practice can be proposed. It is important to emphasize the numerous health benefits to be gained with higher physical activity and fitness levels in persons with overweight or obesity. Given that effects on weight (and fat) loss as such were found of modest size, the implementation of exercise training programs in persons with overweight or obesity should primarily aim to increase physical fitness, reduce cardiometabolic risk, and improve quality of life. These benefits of exercise will very likely improve overall health, even without substantial change in body weight.
Within the scope of a comprehensive approach of management of overweight and obesity, exercise prescription will be carried out in conjunction with dietary advice, psychological interventions, pharmacotherapy when needed and/or available, and in persons with severe obesity, bariatric surgery. 19,23 The five A's strategy consisting Ask, Assess, Advise, Agree, and Assist (or Arrange) 24,25 appears well adapted in this perspective, especially for the aim to individually tailor the exercise prescription to the needs, preferences, capacity, corpulence, and health status of patients.
The topic of physical activity and exercise should be discussed as part of each encounter between a health professional and any patient with overweight or obesity ("Ask"). Information about the benefits expected should be provided. An evaluation of habitual physical activity and physical fitness is a logical follow-up of dietary and lifestyle assessment in patients ("Assess"). Simple questionnaires designed for use in the setting of general practice can help. 26 There is currently no specific recommendation about when to perform a maximal exercise test in subjects with overweight or obesity (without diabetes). Such testing may however be important to search for underlying coronary heart disease in high-risk patients and/or to adapt the exercise load on a quantitative basis. 27 A specific goal should be defined for the patient and specific activities or programs proposed to reach that goal ("Advise"). Goals will be shared between health professionals and patients ("Agree"). Counseling will be tailored to the individual needs of the patients taking into account physical fitness, co-morbidities, stage of change regarding physical activity, barriers to increase physical activity, and opportunities offered in the living environment.
The process of counseling will develop over time with frequent reassessment and subsequent adaptation ("Assist"). Interventions rest on behavior change and a major challenge is how to improve adherence to a new lifestyle over time. 28 When recommending exercise for adults with overweight or obesity, it is important to balance any positive with potential negative effects on health. In the general population, exercise is associated with an increased risk of musculoskeletal injuries and adverse cardiac events, but there is evidence from non-randomized trials and observational studies that the benefits of exercise far outweigh the risks in most adults. 29 Musculoskeletal injuries are the most frequent negative side effects of exercise. There is however very little information on musculoskeletal injuries in adults with overweight or obesity during exercise interventions. Some studies in this setting did not find more injuries in the intervention group than in the control group, 30,31 while other studies reported more injuries in an exercise intervention group. 32, 33 We are not aware of studies that directly compared the injury risk in adults with or without overweight or obesity. The incidence of both acute myocardial infarction and sudden death is greatest in the least habitually physically active individuals performing unaccustomed physical activity. 34 It is likely that a larger percentage of adults with overweight or obesity falls in this inactive group compared to lean subjects. On the other hand, the largest benefits on allcause mortality are attained when this group is moved to an at least "moderately active" level. 35 By analogy with the general population, overall it seems prudent to advise habitually inactive adults with obesity to become more active by a gradual progression of exercise volume by adjusting exercise duration, frequency, and/or intensity. 29