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Pharmacology for Nurses

32.1 Introduction to Weight Management

Pharmacology for Nurses32.1 Introduction to Weight Management

Learning Outcomes

By the end of this section, you should be able to:

  • 32.1.1 Describe the pathophysiology of overweight and obesity.
  • 32.1.2 Identify clinical manifestations related to obesity.
  • 32.1.3 Identify the etiology and diagnostic studies related to obesity.
  • 32.1.4 Describe nonpharmacologic measures to reduce weight.

Overweight and obesity are terms that can be used to describe the increase in the size and number of fat (adipose) cells in the body. There are two ways that adipose tissue increases in the body. Hyperplasia of adipose tissue is an increase in the number of fat cells in the body. Hypertrophy is an increase in the size of fat cells. Both genetics and lifestyle, mainly a diet high in fat, affect hyperplasia and hypertrophy of adipose tissue. There is a strong correlation between genetics and adipose tissue growth. Adipose tissue begins to develop in a fetus by the second trimester. Despite a genetic predisposition, lifestyle behaviors can impact developing overweight or obesity.

Simply stated, excess weight gain that can lead to overweight or obesity can be caused by ingesting more calories than the body needs to function. The American Heart Association (2020) notes that a healthy diet that includes fruits, vegetables, whole grains, low-fat dairy products, and lean proteins low in saturated fats reduces the risk of cardiometabolic diseases in the United States. However, there are many reasons why people ingest more calories than what is needed by the body. One major factor is the increased availability and consumption of highly processed convenience foods. These foods are often high in sugar and fat. Unfortunately, high-calorie, high-sugar, high-fat, processed foods are often less costly than healthier foods. People struggling with finances or living in a food desert (an area where people have extremely limited access to healthy, affordable food) often buy low-cost, high-sugar, high-sodium, and high-fat foods that are cheaper than healthy food choices.

Obesity is recognized as a complex medical condition. In addition to diet, there are other factors that can increase the likelihood of a person developing obesity, including genetics, lack of sleep, decreased or restricted physical activity, certain medications, and stress. Obesity raises an individual’s risk for developing heart disease, hypertension, diabetes, and cancer (National Heart, Lung, and Blood Institute, 2022).

Weight Stigma

Society typically values a person who is “thin and fit,” despite the fact that almost 75% of Americans live with overweight or obesity. Obesity stigma is characterized by prejudice, stereotyping, and discriminating bias and actions toward people with obesity, often fueled by inaccurate ideas about the causes of obesity (Westbury et al., 2013). Weight stigma often stereotypes people with overweight or obesity negatively as lacking self-discipline, being lazy or sloppy, and lacking intelligence. These stereotypes may result in discrimination in relationships, social acceptance, employment, and recognition. Weight discrimination often leads to adverse health consequences such as binge eating, psychological and physiological stress, weight gain, and avoidance of participating in healthy behaviors and provider follow-up (Lee et al., 2021). Weight stigma may be internalized by the person with overweight or obesity. Unfortunately, clients may encounter weight stigma as a bias among health care professionals (American College of Obstetricians and Gynecologists, 2019). However, individuals may have their own phrasing and preferences for how they discuss their body size, health, and weight, and nurses should consider those preferences as well.

Overweight and obesity are medical conditions. As with all medical conditions, health care professionals should approach these conditions with a focus on a client-centered treatment plan. Physicians, nurses, physical therapists, nutritionists, and fitness professionals are a few of the types of health care professionals who have contributed to weight bias, stigma, and discrimination by labeling people with overweight and obesity as “noncompliant,” furthering the weight stigma (World Obesity Federation, n.d.). How health care professionals engage in conversations and use terminology with clients is vital to avoid further bias and weight stigma. Using person-first terms such as “person with obesity” instead of “obese person” is recommended for health care professionals. The first term identifies the client as having a condition rather than defining the person as obese. The terms “morbidly obese,” “fat,” and “obese” have been found to be the most stigmatizing, whereas “weight problem,” “unhealthy weight,” and “high BMI” have been found to be the most motivating and least offensive language options for discussing weight with clients (American College of Obstetricians and Gynecologists, 2019).

In addition to being thoughtful in their verbal communications, health care professionals can decrease weight stigma by implementing individualized client-centered weight counseling, encouraging healthy lifestyle behaviors, displaying empathy, and being supportive. Above all, health care professionals should treat overweight and obesity as a medical condition requiring an interprofessional, individualized treatment plan. Nonpharmacological modalities such as meal planning and increased physical activity are encouraged before moving on to weight-loss drugs and bariatric procedures or surgeries. Health care professionals should focus on the consequences, complications, and comorbidities of overweight and obesity, while being certain that they are not simply promoting a "thin body ideal." For example, health care professionals should not assume that a person with overweight or obesity is unable or unwilling to participate in certain activities, such as physically challenging events. And healthcare professionals should never assume or imply that people with overweight or obesity should be unhappy in their bodies.

Overweight Versus Obesity

Overweight and obesity both are defined as abnormal or excessive fat accumulation that may impair health. However, overweight and obesity are not the same thing.

Body mass index (BMI) is a simple index of weight-for-height that is commonly used to classify overweight and obesity in adults. For adults, the World Health Organization (WHO) defines overweight as a BMI greater than or equal to 25 and obesity as a BMI greater than or equal to 30 (WHO, 2021). Being overweight may change the way the body functions and may lead to adverse health effects. If the body is overweight for a prolonged period, it progressively may lead to obesity (Mayo Clinic, 2023c).

Body fat alone is not a disease. In fact, the human body requires fat for energy and to function. Body fat insulates and protects vital organs. The body cannot produce fat on its own. It is essential for humans to ingest cholesterol, triglycerides, and essential fatty acids (EFAs) for basic metabolic and immune functions and to supply the body with the fat-soluble vitamins A, D, E, and K (MedlinePlus, 2023). Despite the importance of fats in the human body, regulation is key to avoiding developing overweight or obesity.

Body Mass Index

The BMI is calculated for adults by first determining a person’s height and weight. The weight in pounds is divided by the height in inches and then multiplied by a conversion factor of 703 to obtain the BMI. To determine the BMI using the metric system, divide the weight in kilograms by the height in square meters and then multiply the result by 10,000. Although the BMI is calculated in the same way for children and teens, clinicians interpret the findings for them differently. For children and adolescents, refer to the CDC Growth Charts.

BMI for adults 20 years and older (see Figure 32.2):

  • Healthy weight: 18.5–24.9 kg/m2
  • Overweight: 25.0–29.9 kg/m2
  • Obese: 30.0 kg/m2 and greater

These parameters may not apply to athletes, body builders, or people who exercise a lot because a BMI may be higher in athletes due to their increased muscle mass. Also, BMI measurements are based on anthropometric measurements of White people. Body fat distribution differs by race and ethnicity, such as among Hispanic, Black, East Asian, and South Asian populations (Nair, 2021). The BMI interpretations should be adjusted based on ethnicities (Harvard T. H. Chan School of Public Health, n.d.). Furthermore, the American Medical Association indicates that BMI should not be used as a sole determinant of health and risk. Rather, it should be used in conjunction with measurements of body adiposity index, relative fat mass, waist circumference, and visceral fat, as well as considerations of body composition, genetic factors, metabolic factors, and other measures (American Medical Association, 2023).

The significance of an increased BMI should be determined by a health care professional and discussed with clients on an individual basis. When obesity is determined to be detrimental to health, it is further classified as:

  • Class I obesity: 30–34 kg/m2
  • Class II obesity: 35–39 kg/m2
  • Class III obesity: 40+ kg/m2

Treatment for obesity is often determined by the class of obesity the client fits into, as determined by a health care professional. Class III obesity is most often linked to serious health conditions.

This chart shows how to calculate B M I based on height and weight. The height information is in feet and meters, and the weight information is in both pounds and kilograms. A BMI of less than 18.5 is underweight, 18.5 to 25 is normal, 25 to 30 is overweight, and more than 30 is obese. According to the chart, a person who is 6 feet 6 inches or 2 meters tall weighing 210 pounds or 100 kilograms is overweight. A person who is 6 feet 6 inches or 2 meters tall is considered obese at 270 or more pounds or 120 or more kilograms.
Figure 32.2 This chart is a simple way to calculate BMI for adults based on height and weight in kilograms. BMI should be used as one evaluation in conjunction with other measures of health. (credit: modification of work from Psychology 2e. attribution: Copyright Rice University, OpenStax, under CC BY 4.0 license)

Factors Associated with Obesity

Obesity at a minimum alters the body’s metabolism. Metabolism is the body’s process of converting calories into energy for optimal functioning. When the body takes in too many calories, it stores the excess as adipose tissue. Excess adipose tissue secretes hormones that start an inflammatory process in the body that may lead to chronic inflammation and insulin resistance. With insulin resistance, the body does not respond to insulin to properly regulate blood glucose levels. This affects the body’s ability to use glucose for energy in the muscles and other body organs, and glucose builds up in the bloodstream (hyperglycemia). The pancreas then does what it is supposed to do and produces more insulin to combat hyperglycemia. Over time, this circle leads to type 2 diabetes mellitus. Obesity raises the incidence of developing type 2 diabetes 7–12 times that of a person of a healthy weight (Cleveland Clinic, 2022).

Hormonal weight gain due to aging is another concern, especially for postmenopausal clients. According to Mayo Clinic (2023d), hormonal changes due to menopause may cause up to 1.5 pounds of weight increase, particularly in the abdominal area. However, an active lifestyle and healthy eating patterns can minimize postmenopausal weight gain.

In addition to hyperglycemia from chronic inflammatory processes and insulin resistance, serum lipids (cholesterol and triglycerides) may increase, leading to hyperlipidemia. The combination of hyperglycemia and hyperlipidemia leads to hypertension (high blood pressure). These risk factors are often grouped together in a condition called metabolic syndrome, which is a collection of risk factors, including overweight and obesity, that drastically increases the chance of a person developing hypertension, diabetes, heart disease, and stroke. In addition to steering the body to metabolic syndrome, increased BMI coupled with hyperglycemia, hyperlipidemia, hypertension, and/or chronic inflammation increases the risk of atherosclerosis, cardiovascular disease, and coronary artery disease. As metabolic syndrome may be prevented with client education on nutrition and meal planning, it is recommended that providers consider referring clients to a registered dietician for individual meal planning education.

The excess circulating serum lipids and glucose eventually make their way to the liver, kidneys, and gallbladder. The liver and kidneys are responsible for filtering the blood. Excessive lipids in the liver may lead to steatosis and nonalcoholic fatty liver disease (NAFLD). Long-term storage of excess lipids in the liver can increase chronic inflammation in the liver, triggering hepatitis and eventually possible cirrhosis. Prolonged hyperglycemia and hypertension are taxing on the kidneys and eventually affect the functioning of the renal tissue, leading to possible chronic kidney disease. High cholesterol can also accumulate in the gallbladder, leading to cholelithiasis, which further impairs metabolism.

In addition to the metabolic issues that can lead to serious chronic diseases, overweight and obesity have detrimental direct effects on the body due to the excess adipose tissue. The strain primarily affects the musculoskeletal and respiratory systems. The excess weight on the musculoskeletal system impairs the body’s ability to support itself. It also impairs mobility. The added weight on the soft tissues, bones, joints, tendons, and ligaments causes stiffness and pain. This may lead to injuries and diseases such as low back pain, osteoarthritis, and gout, further impeding mobility.

Excess body fat also puts additional strain on the respiratory system, contributing to obesity hypoventilation syndrome, sleep apnea, and asthma. Obesity hypoventilation syndrome (OHS) is a respiratory condition that is a direct outcome of obesity, especially Class III obesity. “OHS is defined by the combination of obesity (body mass index [BMI] ≥30 kg/m2), SDB [sleep-disordered breathing], and awake daytime hypercapnia (awake resting PaCO2 [the partial pressure of carbon dioxide] ≥45 mm Hg at sea level), after excluding other causes for hypoventilation” (Mokhlesi et al., 2019).

Physiological Factors

Physiological factors are related to the chemical and physical processes that occur within the body. Various physiological factors affect weight management including basal metabolic rate (BMR), circadian rhythm and sleep cycles, hormones, thermogenesis, physical fitness and strength, digestive health and gut flora, prenatal and postnatal factors, and physiological response to stress. The foundational physiological factor in weight management is the BMR, which is the amount of energy required to sustain the essential body functions of life. The physiology of the BMR is influenced by several factors including sex, muscle mass, body size, amount of sleep, and genetics. Males have a greater BMR than females, which accounts for the muscle mass and fat distribution differences. Muscles burn about 4 calories more per hour than adipose tissue. Although males have a greater muscle mass than females, it is important for females to maintain a proper proportion of lean muscle mass to maintain a higher BMR.

An adequate amount of sleep is fundamental for maintaining physical, psychological, and emotional health. For optimal health, 7–9 hours of sleep per night is recommended. Sleep is essential to proper weight management. Poor sleep is associated with glucose intolerance and insulin resistance. Additionally, sleep deprivation affects metabolic rates, hormones that regulate metabolism, and even eating habits (Papatriantafyllou et al., 2022). The effects of sleep on worsening obesity have been studied quite a bit in children. Results demonstrate that just 1 hour less sleep per night from normal sleep patterns can lead to an increase in obesity in children and teens (Yadav & Jawahar, 2023).

It is important to pay attention to an individual’s internal clock (circadian rhythm) in respect to sleep as well. Hormonal regulation affecting eating and sleeping is controlled by a person’s physiological circadian rhythm. Not paying attention to the urge to sleep based on the physiological internal clock can alter weight management. Incidentally, eating too late at night can not only alter the circadian rhythm but also interfere with sleep (Reynolds, 2022).

Several hormones play a role in weight management, influencing appetite and the ability to utilize adipose tissue as an energy source. Insulin, an anabolic hormone, regulates glucagon and fat for energy. Ghrelin is a hormone that controls hunger and satiety. Leptin is another hormone that is primarily involved in satiety. According to the Cleveland Clinic (2023a), research demonstrates that some people may have leptin resistance, which may lead to weight gain by inhibiting satiety, increasing hunger, and decreasing metabolism. Glucagon is a hormone that stimulates hepatic glucose production (gluconeogenesis). Weight gain is promoted when insulin and ghrelin are chronically elevated and leptin and glucagon are chronically low. Many factors affect this cycle, including sleep deprivation.

Thermogenesis is an integral process of the body’s metabolic functions. It is the production of heat in the human body, specifically in brown adipose tissue and skeletal muscle. Thermogenesis burns calories to produce heat/energy, creating a negative energy balance that leads to weight loss. It is sometimes referred to as “fat burning” due to the burning of specifically adipose tissue. There are three primary types of thermogenesis: nonexercise-activity thermogenesis (NEAT), exercise-associated thermogenesis (EAT), and diet-induced thermogenesis (DIT). NEAT occurs under normal natural physical activity and burns calories associated with activities of daily living. EAT refers to calories that are burned with purposeful exercise. DIT is the production of heat (calorie burning) that occurs after eating. Intentionally increasing thermogenesis is a nonpharmacological method of weight management (discussed later in the chapter).

Genetic Factors

In terms of factors affecting obesity, heredity and genetic factors have been considered part of a multifactorial cause. Genome studies demonstrate genetic biological reinforcement and the role of the brain in weight management (Loos & Yeo, 2021). Genes affect the amount of fat stored in an individual’s body and fat distribution. Several genes play a role in the pathogenesis of overweight and obesity. The most significant is the fat mass and obesity-associated (FTO) gene. Genetic variation in the first segment of the FTO gene is largely related to adiposity. This may lead to long-term overweight and obesity consequences as an adult (Huang et al., 2023). Genetics may also play a role in digestion and metabolism; however, genetics are not the sole cause of obesity.

Ethnicity has also been correlated with excess weight. Non-Hispanic Black adults (49.9%) had the highest age-adjusted prevalence of obesity, followed by Hispanic adults (45.6%), non-Hispanic White adults (41.4%), and non-Hispanic Asian adults (16.1%) (CDC, 2022c). There is some evidence that the differences may be linked to racial genetics that affect body composition and fat distribution.

Environmental Factors

In most discussions about the genetic influences of obesity, the role of family environment is also stressed as a major factor of obesity. Family environment may lead to sedentary and poor lifestyle behaviors. There may also be socioeconomic factors related to the family environment. In the United States over the last few decades, there has been an increased incidence of choosing ultra-processed and fast food for meals. This is coupled with a decrease in physical activity, especially in children. Food deserts are also a concern with weight management. Healthy food accessibility is a major environmental factor, especially in lower-income and minority neighborhoods, which have approximately 30% fewer supermarkets (Yadav & Jawahar, 2023).

The family environment also greatly influences lifestyle behaviors such as physical activity, eating behaviors, sleep patterns, and reactions to stress. All of these can affect weight management. Physical spaces such as where one lives, works, and socializes have a large familial influence and can affect weight management. Gurka et al. (2018) found that the prevalence of obesity fluctuates across the United States based on geographic areas. The highest levels of obesity, diabetes, and metabolic syndrome in the United States are in the Midwest and Southern regions.

Psychological Factors

According to the National Council on Aging (Vafiadis, 2021), research demonstrates that there are barriers to treatments based on the complex interrelatedness between obesity and mental health. Most discussions on obesity focus on the physical consequences such as cardiovascular challenges, type 2 diabetes, and musculoskeletal conditions. Rarely are the emotional and mental health impacts related to obesity considered in treatment plans (Vafiadis, 2021). There are significant psychological burdens associated with obesity and its comorbidities. People with obesity often exhibit more self-esteem issues, body-image dissatisfaction, anxiety, depression, low quality of life, and discrimination (Vafiadis, 2021).

Due to the large body mass from obesity and the detrimental effects of comorbidities, people with obesity often are unable to participate in activities they enjoy, such as spending time with family and friends, traveling, attending social events, or participating in hobbies. Social isolation may lead to loneliness, difficulty coping, and depression. Furthering the potential for depression is society’s negative attitude toward overweight and obesity. People with obesity often experience weight bias, being stereotyped as lacking self-discipline or being lazy. Weight bias may also be present among health care providers (American College of Obstetricians and Gynecologists, 2019). These critical biases may lead to discrimination. Discriminatory behaviors and weight bias may exacerbate depressive symptoms.

There is a reciprocal relationship between obesity and mental health concerns. Although overweight and obesity may trigger consequences on mental and emotional health, various mental and emotional conditions may, in turn, lead to behaviors causing weight gain. Chronic stress, anxiety, depression, and bipolar disorder may cause a person to use food for comfort or decrease their interest in participating in physical activities. Self-medication with food is common in clients with depressed mood, sleep disturbances, and anxiety due to serotonin deficiency (Vafiadis, 2021). Serotonin is a vital neurotransmitter for optimal functioning of body processes, enhancing learning, memory, and happiness. Serotonin also regulates sleep, mood, digestion, satiety, bone health, wound healing, and sexual desires. When there is an imbalance of serotonin, physical and psychological symptoms such as depression, mania, and anxiety may occur (Cleveland Clinic, 2023b). The complex interrelationship between obesity and mental health requires further exploration of the connections and weight-management strategies.

Nonpharmacologic Weight Management

Obesity is an epidemic worldwide caused by biological, genetic, social, environmental, and behavioral factors. There is no single treatment or easy solution to reducing overweight and obesity; it is a multifaceted dilemma requiring comprehensive multidimensional approaches that are individualized to the client. Weight reduction focuses on meal planning and increasing physical activity to reduce weight, thus preventing or reducing obesity complication. Nonpharmacological weight-loss strategies, such as behavioral lifestyle interventions of eating less and moving more, should be initiated before drugs and/or procedures. Collaborative short-term weight-management and behavioral goals should be developed with an experienced health care professional in weight management. Client education and support are vital to weight-loss and management success.

A healthy meal plan should be balanced with moderate lean proteins and complex carbohydrates and should be low in fat and sugar. Foods with a glycemic index (GI) of less than 55 are recommended to promote stable blood glucose levels that aid in weight management. Foods in this category include most fruits and vegetables, beans, minimally processed grains, pasta, low-fat dairy foods, and nuts (Harvard Health, 2023).

Lean-protein foods such as fish and poultry increase the basal metabolic rate while balancing the release of insulin and serum glucose levels. This results in glucagon mobilizing adipose tissue and promoting more weight loss. A consistent eating schedule also enhances constant blood glucose levels. Controlling blood glucose levels enhances the body’s ability to burn stored body fat while controlling hunger.

Eating many raw fresh fruits and vegetables is recommended to increase dietary fiber and promote clean eating. Clean eating refers to eating foods that are in their natural state and unprocessed because these are nutrient-dense foods and free of synthetic chemicals, preservatives, and additives such as sugar and salt (Dutter, 2019). These additives are detrimental to health and often promote weight gain. Choosing foods that the client likes will encourage adherence. Individual considerations must be taken into account to provide optimal nutrition, promote weight loss, and ensure success. Eating fewer calories and increasing physical activity coupled with behavior modification is the only way to lose weight. However, clients must be educated on eating the right foods in a collaborative weight-management plan determined with a health care professional.

The Mediterranean diet, which is high in fish (especially those species high in omega-3 fatty acids), fresh fruits and vegetables, whole grains, nuts, and olive oil, has been shown to reduce the risk of cardiovascular disease and metabolic syndrome while promoting weight loss. Extra virgin olive oil is the main source of dietary fat in a Mediterranean diet.

Some foods that help boost metabolism and quickly burn body fat are classified as thermogenic foods. Proteins are considered a thermogenic food because the digestion process takes the longest and burns more calories. High-protein foods incorporated into a daily meal plan help with weight loss by burning more calories. Plant-based proteins such as lentils, chickpeas, black beans, hemp seeds, nuts, quinoa, tofu, and peanut butter help to increase metabolism. Lean animal proteins such as poultry (white meat), fish (salmon, tuna, mackerel, herring, and sardines), pork tenderloin, lean beef cuts, and eggs curb hunger while promoting thermogenesis. Caffeine and green tea are excellent additives in a meal plan for thermogenesis. Other foods to enhance thermogenesis are coconut oil, ginger, and capsaicin/red pepper. High-fiber foods also help increase thermogenesis.

Supplements such as garcinia cambogia, yohimbine, and bitter orange may also promote thermogenesis (National Institutes of Health, 2022). Other supplements that help with weight loss and management include:

  • Chromium picolinate: Stabilizes metabolism of carbohydrates (reduces sugar cravings)
  • Essential fatty acids (EFAs): Provide cellular nutritional support and appetite control
  • Amino acids: Decrease cravings and promote weight loss
  • Kelp: Balances minerals and aids in weight loss
  • Spirulina: Protein source, stabilizes blood glucose
  • Multivitamins: Provide nutritional support
  • Herbs: See Section 32.4 for more on herbal supplements

In addition to a healthy meal plan, increasing physical activity promotes weight loss. Adding an exercise program should be done in consultation with the client’s health care provider and an exercise professional. Limiting sedentary activities is key to enhancing weight loss. If a reduction in caloric intake and increasing physical activity is ineffective after 12 months, drugs such as anorexiants, lipase inhibitors, and herbal supplements may be used to aid in weight loss.

Clinical Tip

Talk to Your Client

When discussing goals with a client who needs to lose weight, it is important to talk about all aspects of the client’s life that affect weight management. Sustainable weight loss requires a comprehensive approach with a foundation on eating balanced, heart-healthy foods and getting consistent physical activity, along with adequate sleep and stress reduction.

Special Considerations

Weight-Loss Medications and Supplements

Individual factors such as age, sex, and ethnicity must be considered with the use of all weight-loss medications and supplements. Older clients may not be able to absorb and excrete drugs, leading to ineffective or toxic doses. Safety concerns for various racial/ethnic groups include differences in absorption, metabolism, distribution, and excretion due to genetic components and possible cytochrome P-450 (CYP) deficiencies. Additionally, nurses must assess the client's ability to understand and comprehend medication instructions and education.

(Source: National Institutes of Health, 2022)


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