Although many persons with obesity can lose weight by lifestyle (diet and physical activity) therapy, successful long‐term weight loss is difficult to achieve, and most people who lose weight regain ...their lost weight over time. The neurohormonal, physiological, and behavioral factors that promote weight recidivism are unclear and complex. The National Institute of Diabetes and Digestive and Kidney Diseases convened a workshop in June 2019, titled “The Physiology of the Weight‐Reduced State,” to explore the mechanisms and integrative physiology of adaptations in appetite, energy expenditure, and thermogenesis that occur in the weight‐reduced state and that may oppose weight‐loss maintenance. The proceedings from the first session of this workshop are presented here. Drs. Michael Rosenbaum, Kevin Hall, and Rudolph Leibel discussed the physiological factors that contribute to weight regain; Dr. Michael Lowe discussed the biobehavioral issues involved in weight‐loss maintenance; Dr. John Jakicic discussed the influence of physical activity on long‐term weight‐loss maintenance; and Dr. Louis Aronne discussed the ability of drug therapy to maintain weight loss.
Abstract
The prevalence of obesity, measured by body mass index, has risen to unacceptable levels in both men and women in the United States and worldwide with resultant hazardous health ...implications. Genetic, environmental, and behavioral factors influence the development of obesity, and both the general public and health professionals stigmatize those who suffer from the disease. Obesity is associated with and contributes to a shortened life span, type 2 diabetes mellitus, cardiovascular disease, some cancers, kidney disease, obstructive sleep apnea, gout, osteoarthritis, and hepatobiliary disease, among others. Weight loss reduces all of these diseases in a dose-related manner-the more weight lost, the better the outcome. The phenotype of "medically healthy obesity" appears to be a transient state that progresses over time to an unhealthy phenotype, especially in children and adolescents. Weight loss is best achieved by reducing energy intake and increasing energy expenditure. Programs that are effective for weight loss include peer-reviewed and approved lifestyle modification programs, diets, commercial weight-loss programs, exercise programs, medications, and surgery. Over-the-counter herbal preparations that some patients use to treat obesity have limited, if any, data documenting their efficacy or safety, and there are few regulatory requirements. Weight regain is expected in all patients, especially when treatment is discontinued. When making treatment decisions, clinicians should consider body fat distribution and individual health risks in addition to body mass index.
This Scientific Statement critically reviews the definition of obesity, providing a list of assessment methods, obesity-related diseases, and prevention measures.
The beneficial effects of physical activity (PA) are well documented, yet the mechanisms by which PA prevents disease and improves health outcomes are poorly understood. To identify major gaps in ...knowledge and potential strategies for catalyzing progress in the field, the NIH convened a workshop in late October 2014 entitled “Understanding the Cellular and Molecular Mechanisms of Physical Activity-Induced Health Benefits.” Presentations and discussions emphasized the challenges imposed by the integrative and intermittent nature of PA, the tremendous discovery potential of applying “-omics” technologies to understand interorgan crosstalk and biological networking systems during PA, and the need to establish an infrastructure of clinical trial sites with sufficient expertise to incorporate mechanistic outcome measures into adequately sized human PA trials. Identification of the mechanisms that underlie the link between PA and improved health holds extraordinary promise for discovery of novel therapeutic targets and development of personalized exercise medicine.
This Perspective reports on the NIH October 2014 workshop “Understanding the Cellular and Molecular Mechanisms of Physical Activity-Induced Health Benefits,” where major gaps in knowledge, as well as potential strategies for catalyzing progress in the field of physical activity, were discussed and the outcome consensus points reached.
There is evidence to support that low fitness and physical activity, excess body weight, and excess abdominal fatness are associated with increased health risk. Moreover, evidence exists to support ...that sufficient levels of physical activity can significantly improve body weight, fatness, and health risk. Physical activity has been shown to have a modest effect on body weight that is typically <3% of initial body weight, but has an additive effect when combined with dietary restriction. Moreover, physical activity has been shown to be an important behavioral factor for enhancing long-term weight loss and minimizing weight regain; however, this may require relatively high doses of physical activity that approach 300 min/week. Physical activity may concurrently reduce abdominal adiposity, and which may serve as a pathway by which there is also an improvement in health-related risk factors for various chronic diseases. There are important areas of research that require further investigation, with particular need to further examine the dose of physical activity that significantly affects these health outcomes. Moreover, there is a need for improved interventions to promote the adoption and long-term maintenance of physical activity, which can lead to improved weight control, abdominal adiposity, and chronic disease risk factors. Future research is also needed to understand the physiological/metabolic pathways and mechanisms that explain the influence of physical activity on long-term regulation of body weight.
PURPOSEConduct a systematic umbrella review to evaluate the relationship of physical activity (PA) with all-cause mortality, cardiovascular mortality, and incident cardiovascular disease (CVD); to ...evaluate the shape of the dose–response relationships; and to evaluate these relationships relative to the 2008 Physical Activity Guidelines Advisory Committee Report.
METHODSPrimary search encompassing 2006 to March, 2018 for existing systematic reviews, meta-analyses, and pooled analyses reporting on these relationships. Graded the strength of evidence using a matrix developed for the Physical Activity Guidelines Advisory Committee.
RESULTSThe association of self-reported moderate-to-vigorous physical activity (MVPA) on all-cause mortality, CVD mortality, and atherosclerotic CVD—including incident coronary heart disease, ischemic stroke and heart failure—are very similar. Increasing MVPA to guidelines amounts in the inactive US population has the potential to have an important and substantial positive impact on these outcomes in the adult population. The following points are clearthe associations of PA with beneficial health outcomes begin when adopting very modest (one‐third of guidelines) amounts; any MVPA is better than none; meeting the 2008 PA guidelines reduces mortality and CVD risk to about 75% of the maximal benefit obtained by physical activity alone; PA amounts beyond guidelines recommendations amount reduces risk even more, but greater amounts of PA are required to obtain smaller health benefits; and there is no evidence of excess risk over the maximal effect observed at about three to five times the amounts associated with current guidelines. When PA is quantified in terms of energy expenditure (MET·h·wk), these relationships hold for walking, running, and biking.
CONCLUSIONSTo avoid the risks associated with premature mortality and the development of ischemic heart disease, ischemic stroke, and all-cause heart failure, all adults should strive to reach the 2008 Physical Activity Guidelines for Americans.
PURPOSETo provide an overview of relationships between sedentary behavior and mortality as well as incidence of several noncommunicable diseases and weight status reported in the 2018 Physical ...Activity Guidelines Advisory Committee Scientific Report (2018 PAGAC Scientific Report), and to update the evidence from recent studies.
METHODSEvidence related to sedentary behavior in the 2018 PAGAC Scientific Report was summarized, and a systematic review was undertaken to identify original studies published between January 2017 and February 2018.
RESULTSThe 2018 PAGAC Scientific Report concluded there was strong evidence that high amounts of sedentary behavior increase the risk for all-cause and cardiovascular disease (CVD) mortality and incident CVD and type 2 diabetes. Moderate evidence indicated sedentary behavior is associated with incident endometrial, colon and lung cancer. Limited evidence suggested sedentary behavior is associated with cancer mortality and weight status. There was strong evidence that the hazardous effects of sedentary behavior are more pronounced in physically inactive people. Evidence was insufficient to determine if bout length or breaks in sedentary behavior are associated with health outcomes. The new literature search yielded seven new studies for all-cause mortality, two for CVD mortality, two for cancer mortality, four for type 2 diabetes, one for weight status, and four for cancer; no new studies were identified for CVD incidence. Results of the new studies supported the conclusions in the 2018 PAGAC Scientific Report.
CONCLUSIONSThe results of the updated search add further evidence on the association between sedentary behavior and health. Further research is required on how sex, age, race/ethnicity, socioeconomic status, and weight status may modify associations between sedentary behavior and health outcomes.
PURPOSEThis systematic umbrella review examines and updates the evidence on the relationship between physical activity (PA) and blood pressure (BP) presented in the 2008 Physical Activity Guidelines ...Advisory Committee Scientific Report.
METHODSWe performed a systematic review to identify systematic reviews and meta-analyses involving adults with normal BP, prehypertension, and hypertension published from 2006 to February 2018.
RESULTSIn total, 17 meta-analyses and one systematic review with 594,129 adults ≥18 yr qualified. Strong evidence demonstrates1) an inverse dose–response relationship between PA and incident hypertension among adults with normal BP; 2) PA reduces the risk of cardiovascular disease (CVD) progression among adults with hypertension; 3) PA reduces BP among adults with normal BP, prehypertension, and hypertension; and 4) the magnitude of the BP response to PA varies by resting BP, with greater benefits among adults with prehypertension than normal BP. Moderate evidence indicates the relationship between resting BP and the magnitude of benefit does not vary by PA type among adults with normal BP, prehypertension, and hypertension. Limited evidence suggests the magnitude of the BP response to PA varies by resting BP among adults with hypertension. Insufficient evidence is available to determine if factors such as sex, age, race/ethnicity, socioeconomic status, and weight status or the frequency, intensity, time, and duration of PA influence the associations between PA and BP.
CONCLUSIONSFuture research is needed that adheres to standard BP measurement protocols and classification schemes to better understand the influence of PA on the risk of comorbid conditions, health-related quality of life, and CVD progression and mortality; the interactive effects between PA and antihypertensive medication use; and the immediate BP-lowering benefits of PA.
PURPOSEA systematic primary literature review was conducted to evaluate the relationship of physical activity—as measured by daily step counts—with all-cause mortality, cardiovascular disease ...mortality, incident cardiovascular disease, and type 2 diabetes mellitus; to evaluate the shape of dose–response relationships; and to interpret findings in the context of development of the Physical Activity Guidelines for Americans, Second Edition.
METHODSA primary literature search encompassing 2011 to March 2018 for existing literature reporting on these relationships was conducted.
RESULTSEleven pertinent articles were identified. Seven longitudinal studies examined the relationship between daily step counts and mortality, disease incidence, or risk. Two studies examined objectively measured steps per day and all-cause mortality; one was restricted to a relatively small elderly population. One study examined cardiovascular events, defined as cardiovascular death, nonfatal myocardial infarction, or nonfatal stroke. The other four longitudinal studies addressed incident type 2 diabetes. All longitudinal studies reported an inverse relationship between steps per day and outcome risk. In one study, 531 cardiovascular events occurred during more than 45,000 person-years of follow-up. Before intervention, each increment of 2000 steps per day up to 10,000 steps was associated with a 10% lower cardiovascular event rate. Also, for every increase of 2000 steps per day over baseline, there was an 8% yearly reduction in cardiovascular event rate in individuals with impaired glucose tolerance.
CONCLUSIONSDaily step count is a readily accessible means by which to monitor and set physical activity goals. Recent evidence supports previously limited evidence of an inverse dose–response relationship of daily steps with important health outcomes, including all-cause mortality, cardiovascular events, and type 2 diabetes. However, more independent studies will be required before these observations can be translated into public health guidelines.
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