Overview of Obesity: Physiology and Nonpharmacologic Management

Educational Objectives

The goal of this program is to improve diagnosis and management of obesity. After hearing and assimilating this program, the clinician will be better able to:

1. Explain outcomes seen in patients after calorie restriction and weight loss.
2. Counsel patients on the benefits of physical activity in weight loss.

Summary

Introduction: obesity is excess body fat or abnormal fat accumulation that poses a risk to health; it is often mischaracterized as a lifestyle choice; obesity is a complex disease that results from gene-gene and gene-environment interactions, and is associated with >230 complications

Weight loss: the therapeutic desired weight loss to resolve a comorbidity varies; a 3% weight loss is sufficient to achieve better glycemic control; however, for remission of diabetes mellitus, ≥15% weight loss is necessary; optimal weight loss for polycystic ovarian syndrome is 10%, but more is needed to achieve conception

Behaviors associated with long-term weight loss maintenance: in order to enroll in the National Weight Control Registry, one must have lost 30 lb or 13.6 kg and maintained that weight loss for ≥1 yr; behaviors associated with weight loss at 1 yr include lower daily dietary intake, participation in regular leisure time physical activity, exercise, greater dietary restraint, less disinhibition, regular self-weighing, and a lower percentage of calories from fat; Thomas et al (2014) showed individuals with greater initial weight loss maintained larger weight losses throughout the entire follow-up period; those who maintained their weight loss for ≥2 yr experienced slower rates of weight regain and continued to maintain larger weight losses at 5 yr and 10 yr; individuals who reported greater physical activity, dietary restraint, self-weighing frequency, and less disinhibition experienced the greatest weight loss; the role of fat in the treatment of obesity is controversial, but maintaining low levels of dietary fat may be associated with better weight loss maintenance

Weight loss maintenance: the body naturally resists weight loss and tries to maintain its current weight; the central nervous system plays a crucial role in dietary and physical activity patterns and in maintaining the weight set point; the hypothalamus and brain stem integrate signals from the periphery that maintain weight within a narrow range; long-term signals (eg, leptin, adiponectin) come from the body's adipose tissue; short-term, meal-related signals come from the gastrointestinal tract, including glucagon-like peptide-1 (GLP-1) and peptide YY (PYY); signals from the pancreas provide information about energy and glucose; when one starts to restrict calories, the body activates compensatory mechanisms that favor weight regain; there is an increase in ghrelin, the hunger hormone, and decreases in satiety hormones (eg, PYY, GLP-1, leptin, insulin) with a large drop in energy expenditure; there is an increase in response to food cues or food-related signals, particularly for energy-dense foods, and an increase in lipolysis (fat loss greater than lean muscle mass) with no increase in fat oxidation capacity; this adaptive thermogenesis predisposes the individual to weight regain and persists for years; individuals who lose weight from a higher starting point need to eat less and exercise more than those who have always been at a lower weight

Diet: there are no significant differences in the amount of weight loss expected between various dietary patterns; the key factor is calories consumed; Sacks et al (2009) showed all participants lost weight and maintained their weight loss to a similar extent, regardless of the macronutrient composition of their diet; Bray et al (2012) examined the effects of energy intake and protein levels on body fat; 25 healthy participants were given 1000 kcal per day for 8 wk; results of the study showed energy intake was the primary predictor of fat gain; Dansinger et al (2015) compared 4 different diets (Atkins, Zone, WeightWatchers, and Ornish) and found the mean weight loss did not differ significantly among these diets; dietary adherence was a crucial factor in determining weight loss success; Litchtman et al (1992) showed participants significantly underestimated their calorie intake by ≈1000 kcal per day

Comprehensive lifestyle management: includes changes in dietary and physical activity; interventions should be intensive, delivered in small groups or 1-on-1 settings for at least 6 to 12 mo, and include an extended follow-up for at ≥2 yr; patients should be counseled to reduce total calories and increase fiber intake; fiber makes one feel fuller and reduces inflammation; physical activity is a key component of weight loss interventions; lifestyle interventions can lead to a moderate initial weight loss of 5% to 7% and long-term weight loss of 3% to 4%; structure is key; Wing et al (1996) found individuals who received additional support, eg, shopping lists, menus, cost sharing for food, or free food, lost more weight and maintained their weight loss better than those who received only behavioral therapy; the rapidity of weight loss has distinct advantages; Nackers et al (2010) showed patients who lost weight quickly had short-term and long-term advantages in terms of weight loss and maintenance; low-calorie diets typically range from 1200 to 1800 kcal per day; very low energy diets are comprised of ≤800 kcal delivered by total diet meal replacement; meal replacements are fortified and contain all the vitamins and micronutrients necessary for calorie restriction

Food products: minimally processed foods are whole foods; olive oil is an example of processed culinary ingredients; processed foods are a combination of whole foods and culinary ingredients to improve shelf life or taste (eg, canned green beans); ultra-processed foods are formulations of ingredients, mostly of industrial use, that result from a series of industrial processes; ultra-processed foods are highly manufactured and often contain significant amounts of added salt, sugar, and fat; these foods are designed to stimulate consumption; avoidance of ultra-processed foods leads to lower calorie intake; Hall et al (2019) compared the effects of ultra-processed and unprocessed diets on weight gain and found a 2-kg weight difference after 14 days; energy density was not well controlled and likely contributed to the lower calorie intake in the unprocessed diet group

Physical activity: contributes only modestly to weight loss but is important for long-term weight loss maintenance; lowering caloric intake is more important for weight loss; walking alone contributes to adequate energy expenditure and has other benefits; physical activity can be divided into smaller intervals throughout the day; it is recommended to incorporate strength training into the routine; there is a need for increased physical activity after reaching a reduced weight state

Interventions: a stepwise approach is used to manage obesity, where each level of intervention builds upon the previous ones; patients with a body mass index (BMI) of ≥27 with weight-related comorbidities are good candidates for anti-obesity medications; BMI cutoffs for bariatric surgery eligibility have been lowered; 1 in 10 adults with obesity does not achieve the minimum recommended weight loss of 5%; heterogeneity in response is expected with any intervention

PLEASE NOTE: In the lecture Clinical Developments in Gout, included in Family Practice Volume 72 Issue 39, the speaker includes information regarding lesinurad; this medication was discontinued in the United States and Europe in 2019.

Readings

Gupta S, Chen M. Medical management of obesity. Clin Med. 2023;23(4):323-329. doi:10.7861/clinmed.2023-0183. View Article; Henderson J, Ehlers AP, Lee JM, et al. Weight loss treatment and longitudinal weight change among primary care patients with obesity. JAMA Netw Open. 2024;7(2):e2356183. doi:10.1001/jamanetworkopen.2023.56183. View Article; Jakicic J, Apovian C, Barr-Anderson D, et al. Physical activity and excess body weight and adiposity for adults. American College of Sports Medicine Consensus Statement. Med Sci Sports Exer. 2024;56(10):2076-2091. doi:10.1249/MSS.0000000000003520. View Article; Janssen T, Van Every D, Phillips S. The impact and utility of very low-calorie diets: the role of exercise and protein in preserving skeletal muscle mass. Curr Opin Clin Nutrition Metab Care. 2023;26(6):521-527. doi:10.1097/MCO.0000000000000980. View Article; Okafor M. Personalized nutrition for obesity management: a mini-review. Int J Med Health Develop. 2024;29(4):285-288. doi:10.4103/ijmh.ijmh_27_24. View Article; Raiman L, Amarnani R, Abdur-Rahman M, et al. The role of physical activity in obesity. Clin Med. 2023;23(4):311-317. doi:10.7861/clinmed.2023-0152. View Article; Sanders L, Mestre L, Ejima K, et al. Body mass index, obesity, and mortality — part II. Nutrition Tod. 2023;58(4):158-164. doi: 10.1097/NT.0000000000000615. View Article.

Disclosures

For this program, members of the faculty and planning committee reported nothing relevant to disclose. Dr. Rothberg's lecture contains information related to the off-label or investigational use of a therapy, product, or device.

Acknowledgements

Dr. Rothberg was recorded at the 40th Annual Internal Medicine Update, held July 26-28, 2024, on Mackinac Island, MI, and presented by the University of Michigan Medical School. For information on upcoming CME activities from this presenter, please visit medschool.umich.edu/offices/cme. Audio Digest thanks the speakers and presenters for their cooperation in the production of this program.

CME/CE INFO

Accreditation:

The Audio- Digest Foundation is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians.

The Audio- Digest Foundation designates this enduring material for a maximum of 0.75 AMA PRA Category 1 Credits™. Physicians should claim only the credit commensurate with the extent of their participation in the activity.

Audio Digest Foundation is accredited as a provider of continuing nursing education by the American Nurses Credentialing Center's (ANCC's) Commission on Accreditation. Audio Digest Foundation designates this activity for 0.75 CE contact hours.

Lecture ID:

FP724402

Expiration:

This CME course qualifies for AMA PRA Category 1 Credits™ for 3 years from the date of publication.

Instructions:

To earn CME/CE credit for this course, you must complete all the following components in the order recommended: (1) Review introductory course content, including Educational Objectives and Faculty/Planner Disclosures; (2) Listen to the audio program and review accompanying learning materials; (3) Complete posttest (only after completing Step 2) and earn a passing score of at least 80%. Taking the course Pretest and completing the Evaluation Survey are strongly recommended (but not mandatory) components of completing this CME/CE course.

Estimated time to complete this CME/CE course:

Approximately 2x the length of the recorded lecture to account for time spent studying accompanying learning materials and completing tests.