Continuing Education Activity

Sustained weight loss is well-known to be challenging. Everywhere one looks, a new diet or exercise strategy promises to be the magic bullet to lose weight. In reality, weight loss is a complex process encompassing changes in diet, physical activity, and other behavioral modifications. Following an initial period of steady weight reduction, individuals attempting to lose weight frequently experience a frustrating plateau where progress halts.

This activity explores the physiological mechanisms contributing to weight loss plateaus and examines how metabolic adaptations, hormonal variations, and energy expenditure adjustments contribute to this phenomenon. The activity provides evidence-based strategies to help patients overcome weight loss plateaus, including dietary changes, exercise adjustments, behavioral techniques, pharmacotherapy, and bariatric surgery. By understanding the underlying physiology and applying targeted interventions, healthcare professionals can better support individuals in achieving sustained weight loss and improving their overall health.

Objectives:

• Identify the physiologic mechanisms and metabolic adaptations contributing to weight loss plateaus in individuals attempting to lose weight.

• Implement individualized, evidence-based strategies, incorporating dietary modifications, exercise adjustments, behavioral interventions, and consideration of pharmacotherapy and bariatric surgery when initial interventions fail to help individuals overcome weight loss plateaus.

• Apply validated counseling techniques to educate and support people in maintaining motivation and adherence during weight loss plateaus.

• Develop approaches for the interprofessional healthcare team to collaborate in adjusting treatment plans to assist people in overcoming weight loss plateaus.

Introduction

Diet and exercise strategies to lose weight abound. People attempting to lose weight must achieve a net caloric deficit to succeed. After an often steady and relatively rapid initial weight reduction, new dieters frequently encounter a weight loss plateau as their bodies adjust to dietary and physical activity changes. Biological adaptations, a decreased resting metabolic rate, and hormonal changes impede continued weight loss. Physiologically, these can reduce energy levels and endurance, cause decreased fat oxidation, and increase the sensation of hunger. Psychologically, the abrupt halt in progress can lead to discouragement.

Clinicians' understanding of the basis of the weight loss plateau is critical for effective patient management. Research demonstrates that while various diets produce similar weight loss over an 8- to 12-week period, maintaining weight loss long-term (greater than 24 weeks) is successful in only about 10% to 20% of individuals.[1][2] Patient frustration with a weight loss plateau contributes to the phenomenon of "yo-yo dieting," as individuals lose weight, reach a plateau, and regain the lost weight. Popular misconceptions that weight loss is a linear process exacerbate this issue, often leading to unrealistic expectations and disappointment.

To help patients overcome these challenges, healthcare professionals must identify the causes of weight loss plateaus and implement practical strategies, such as varying caloric intake, adjusting exercise routines, and incorporating behavioral techniques supported by setting reasonable expectations and motivational counseling. By addressing the physiological, metabolic, and psychological aspects of weight loss plateaus, clinicians can help their patients achieve and maintain long-term weight loss and improved health.

Function

Introduction

More than 35% of men and 40% of women in the United States have obesity. The United States Preventive Services Task Force (USPSTF) guidelines, most recently updated in 2018, recommend universal obesity screening in primary care and intensive lifestyle interventions for individuals with obesity. The American Association of Clinical Endocrinologists guidelines also promote a structured lifestyle approach that includes healthy eating, exercise, and behavior modification for all individuals with overweight or obesity.[3] In addition to recommending a comprehensive weight management program based on dietary changes, physical activity, and behavioral interventions, the National Institute for Health and Care (NICE) outlines the role of pharmacotherapy and bariatric surgery for those with inadequate weight loss after lifestyle modifications.[4][5]

Weight loss plateaus, characterized by weight loss slowing or stopping despite an individual continuing a diet and exercise regimen, affect approximately 85% of dieters.[6] From an evolutionary perspective, stored fat is a protective reserve against periods of food scarcity, and the body resists attempts at significant weight reduction.[7] Weight loss plateaus are complex and determined by physiologic, genetic, environmental, and psychological factors. The body adapts to reduced caloric intake with metabolic adaptations. External influences like the food environment and behavioral fatigue resulting in increased food intake and decreased physical activity contribute to the tendency for weight loss to halt and for people to regain lost pounds slowly over time.

Regardless of the type of diet, plateaus occur weeks to months following the initiation of a weight management program. The American College of Cardiology (ACC) and the American Heart Association (AHA) indicate individuals generally achieve maximal weight loss at 6 months, followed by weight maintenance or slow regain. According to the American Association of Clinical Endocrinologists and the American College of Endocrinology guidelines, weight loss plateaus with pharmacologic treatment typically occur later than with lifestyle intervention, between 6 and 12 months.[8][9][8]

Understanding the mechanisms behind these plateaus, including hormonal regulation, metabolic adaptations, and theoretical models of weight regulation, is crucial when counseling about weight loss strategies. Clinicians who educate patients about the body's natural adaptations to weight loss and proactively address these challenges can support individuals confronting weight loss plateaus. All interprofessional healthcare team members can enhance the likelihood of patients with obesity reaching and maintaining a healthy weight by promoting sustainable dietary and exercise habits while also preparing them for potential setbacks.[10][11][12][11]

Calculating Caloric Balance   

Individuals lose weight when they achieve a calorie deficit, defined as calories consumed less than calories expended.[13] Popular regimens, such as low-carbohydrate, ketogenic, low-fat, DASH, and Mediterranean diets, offer different macronutrient compositions but share the goal of establishing a caloric deficit to facilitate weight loss. Increasing physical activity as a sole weight loss method or in conjunction with diet can also induce a caloric deficit.[14][15] The best diet is one that the individual can consistently follow while maintaining a negative energy balance.[16]

Calculating the total daily energy expenditure (TDEE) is crucial to weight loss planning. The basal metabolic rate (BMR) or resting energy expenditure (REE), often used interchangeably, primarily determines TDEE. Non-resting energy expenditure (NREE), subdivided into exercise activity thermogenesis (EAT), non-exercise activity thermogenesis (NEAT), and the thermic effect of food, comprises the remainder of TDEE. To determine TDEE, clinicians first estimate the BMR using formulas like the Harris-Benedict or Mifflin-St Jeor equations, using body weight, height, gender, and age. Multiplying the calculated BMR by an activity factor reflecting the individual's level of physical activity (ranging from 1.2 for sedentary to 1.9 for very active) estimates the TDEE. For example, a moderately active 30-year-old woman with a weight of 70 kg and a height of 165 cm has a BMR of approximately 1400 calories daily. The BMR is multiplied by 1.6 (for moderate activity), giving an estimated TDEE of 2240 calories, the number of calories required to maintain her current weight.

An energy deficit of 500 to 750 kcal per day usually results in a weight loss of approximately 1 to 2 lb (0.5 to 1 kg) per week, according to ACC, AHA, and The Obesity Society guidelines.[7][17] Aiming for a weekly weight loss of approximately 0.7% of body weight maximizes fat loss while minimizing metabolic adaptations and muscle loss. Guidelines generally do not recommend extreme caloric deficits due to safety, long-term efficacy, and sustainability concerns.[14][18][14] 

Hormonal Regulation and Metabolic Adaptations

Adaptive thermogenesis is the primary physiological adaptation that contributes to weight loss plateaus, slowing or halting weight loss as the body's REE decreases to match the lower caloric intake. REE reduction is greater than the extent predicted by the loss of fat-free mass alone.[19] A lower BMR or REE leads to a lower TDEE.[20] The decrease in BMR may reduce mitochondrial uncoupling protein activity, decrease thermogenesis, and reduce cellular heat production. Consequently, the body becomes more efficient at conserving energy, further contributing to the plateau. Calorie restriction and weight loss also disrupt energy homeostasis, increasing hunger and maintaining fat stores. These adaptations can decrease leptin levels, increase ghrelin levels, and reduce overall energy expenditure, making it more difficult to lose weight. Weight loss causes loss of adipose tissue and lean mass, and the resulting smaller body mass burns fewer calories during NEAT, further contributing to the plateau.[10][11] These changes increase hunger and fatigue, often leading to discouragement and diet cessation with resultant weight gain.[20]

Several hormones are critical in regulating energy expenditure and hunger during weight loss. Leptin, produced by adipocytes, promotes satiety and increases energy expenditure. It circulates roughly in proportion to fat stores, signaling to the brain about the body's level of adiposity compared to baseline. Leptin levels decrease during weight loss due to reduced fat mass, while pre-existing leptin receptor resistance developed in response to longtime, obesity-associated elevated leptin levels may persist. These promote more food consumption and less energy expenditure. Ghrelin, known as the "hunger hormone," stimulates appetite, triiodothyronine (T3) influences the metabolic rate, and insulin regulates macronutrient metabolism and inhibits muscle protein breakdown.[20] Other vital hormones include pro-opiomelanocortin and glucagon-like peptide-1 (GLP-1), which regulate appetite and energy expenditure. A reduction in GLP-1 levels can lead to increased appetite. Peptide YY (PYY), released by the ileum and colon in response to food intake, acts on Y2 brain receptors to promote satiety and reduce food intake. However, PYY levels can decrease during weight loss, reducing the feeling of fullness. Neuropeptide Y, a potent appetite-stimulating neurotransmitter, increases during caloric restriction, promoting food intake, decreasing energy expenditure, and counteracting weight loss efforts. These hormonal changes contribute to the body's resistance to continued weight loss, and all of them can contribute to weight loss plateaus.

Theoretical Models of Weight Loss

No one theoretical model of the complex interactions between genes and the environment in regulating body weight and adiposity thoroughly explains the observations from scientific studies. The set point theory and the settling point theory are the best-known theories. More research is needed to fully understand the physiologic basis of weight loss plateaus.[21][22][23]

The set point theory proposes that a predetermined or "set" level maintained by physiological mechanisms regulates body weight. An active feedback system in the hypothalamus monitors and adjusts energy intake and expenditure to maintain body weight around a genetically predetermined set point. Evidence supporting this theory includes the body's resistance to weight changes through altered metabolism and appetite regulation mechanisms. However, the set point theory does not account for environmental and social influences on obesity or the widespread increase in obesity rates since the 1980s. It also does not explain why many people gain weight over holidays and weekends with wide fluctuations of weight over a year. Although the average weight of a population is relatively stable, much variability exists at the individual level.[24] In general, humans' overall regulation of body weight is not very good, and the fact that many people overeat at certain times of the year suggests a weak level of physiologic control over energy intake. More substantial evidence from animal trials supports the existence of a body fatness or adiposity set-point rather than a weight set-point. In studies of calorie restriction leading to decreased fat stores, a period of hyperphagia and hypometabolism follows, likely involving leptin signaling the brain about the levels of adipose stores.[21]     

In contrast, the settling point, or control theory, proposes that body weight is not actively regulated around a set point but rather "settles" or stabilizes at a point where energy intake and expenditure are balanced, influenced by factors such as diet, physical activity, genetic predisposition, and external influences. This model suggests that body weight results from passive feedback mechanisms, with changes in body adipose stores influencing energy intake and expenditure. The settling point theory accommodates the impact of social and environmental factors on body weight and better explains the obesity epidemic of recent decades. However, it does not fully address biological and genetic aspects of weight regulation.

Another theory, the dynamic equilibrium model, hypothesizes that a balance between energy intake and expenditure regulates body weight while acknowledging this balance is adaptable and responsive to various internal and external influences. Unlike the set-point model, this theory considers body weight as a flexible range rather than a single target. It helps explain why people hit plateaus during weight loss as the body adapts to defend its prior state, adjusting hunger and metabolic rate to favor weight regain when caloric intake is increased. In the dynamic equilibrium model, changes in body weight in either direction cause involuntary changes in energy expenditure, and people usually find a balance that can move in either direction over time.[21] Other theoretical models are the Hall-Guo set point, the Operating Point, and the Dual Intervervention Point models.

Clinical Significance

As a first step in managing weight loss plateaus, clinicians should provide anticipatory guidance about the physiologic changes and their effects on weight loss. Patients who understand the mechanism will more likely embrace effective strategies for achieving sustainable calorie deficits by adjusting their diet and physical activity.

Clinicians should reassess each patient with an updated dietary intake and exercise history, noting any changes in eating habits or activity levels. Ongoing weight loss stimulates appetite by activating the feedback control circuit, and consuming fewer calories requires more effort.[9] Even intermittent lack of adherence to dietary prescriptions can cause weight fluctuations and a plateau. Patients might not be aware that they have gradually begun eating more than they did previously. Sometimes, the plateau reflects that the individual has reached an optimal BMI, and clinicians can commend and advise them on maintaining their new weight.

Several strategies exist for individuals who continue to have an elevated BMI to overcome a weight loss plateau. Patients who experience fatigue and have lost a lot of lean mass may need a "recovery phase" to regain lost muscle and positively impact their metabolism.[25] Additional calories can decrease hunger, improve energy, and normalize altered hormonal levels during a short-term recovery period. Helpful dietary changes include a protein intake of 1.2 to 1.5 g/kg/day to preserve lean mass and promote satiety.[26] In one small European study, consuming a diet with 25% of calories from protein led to a negative energy balance and a higher REE.[27] Eating more fiber-rich foods will lessen hunger by delivering fewer calories per volume of food and slowing gastric emptying time. The AHA and the ACC recommend monitoring dietary intake, physical activity, and weight with food diaries, physical activity logs, and regular self-weighing for patients in structured weight loss programs.[28][29]

Food restriction alone is unlikely to reverse a weight plateau. Patients usually benefit from increasing the duration, frequency, and intensity of physical activity. Resistance training and strength-building exercises promote muscle growth, which increases the BMR and improves insulin sensitivity. Individuals can increase their NEAT by upping their step counts, taking stairs, or using a standing desk for work.[30] Setting specific and measurable exercise goals may help patients reach the  AHA recommendations of at least 200 minutes per week of moderate-intensity physical activity, both resistance training and aerobic, for sustained weight loss.[28] Patients struggling to overcome a weight loss plateau may find increasing exercise more feasible than eating fewer calories; however, they may ultimately need both strategies for success.[27]

Regular contact with healthcare professionals through visits, phone calls, or electronic communication can enhance patient adherence to recommended lifestyle changes. Primary care clinicians can schedule more frequent follow-up visits for brief counseling sessions employing motivational interviewing techniques. Behavior strategies include reinforcing self-monitoring, setting new goals, and addressing barriers to change. Structured behavioral therapy can also be effective in group or individual settings, including online programs that use cognitive behavioral therapy techniques to help patients overcome barriers to weight loss. Readily available tools supporting weight loss include pedometers, food scales, exercise videos, smartwatches, and smartphone applications.

Clinicians should encourage patients to recognize and measure progress beyond the number on the scale, including physical gains such as smaller body measurements, better sleep, improved energy levels and fitness, and decreased joint pain. Patients may require fewer medications to treat chronic obesity-related conditions even without further weight loss. Psychologically, many people report enhanced self-confidence and a more mindful approach to eating as they embrace an active lifestyle and a more nutritious diet.

A study utilizing the Lifestyle Questionnaire for Weight Management (LQ-WM) examined the impact of various lifestyle interventions on continued weight loss among dieters. The LQ-WM, designed for clinical settings, includes 18 items assessing healthy and unhealthy weight-related behaviors, such as calorie tracking, physical activity, and the consumption of unhealthy foods. Additionally, it evaluates motivational levels for behavior change and the influence of body image on self-esteem. The LQ-WM provides a comprehensive Lifestyle Score (LS) to gauge a participant's lifestyle by adding the healthy behaviors and subtracting the unhealthy behaviors. Individuals with a higher LS were more successful in achieving continued weight loss.[31]

Some individuals adhering to lifestyle modifications will reach a seemingly insurmountable weight loss plateau despite complying with recommended changes in diet and exercise. For those with continued obesity despite a significant initial weight reduction, consideration of pharmacotherapy with GLP-1 receptor agonists or other FDA-approved anti-obesity medications is beneficial to facilitate greater weight loss, particularly when paired with behavioral interventions.[32][33][34][32] Patients taking GLP-1 receptor agonists report reduced hunger and increased satiety and tend to experience a weight loss plateau at about a year after beginning treatment, significantly later than those using lifestyle interventions alone.[35] When the BMI is 40 kg/m² or greater, or 35 kg/m² or greater with obesity-related comorbidities, patients may benefit from bariatric surgery. Studies using mathematical models suggest that GLP-1 receptor agonists and bariatric surgery weaken the appetite feedback control circuit regulating body weight, resulting in a longer period of weight loss before a plateau.[9]

These strategies highlight the importance of promoting a balanced lifestyle, adjusting food intake, increasing exercise, and behavioral counseling for weight management. Pharmacotherapy and bariatric surgery provide valuable additional therapies for individuals unable to achieve or maintain a healthy weight using behavioral interventions alone. By incorporating these strategies, clinicians can assist patients in overcoming weight loss plateaus, leading to sustained weight reduction and enhanced health outcomes.

Enhancing Healthcare Team Outcomes

Interprofessional collaboration is essential for optimal patient-centered care, outcomes, and safety. Physicians, nurse practitioners (NPs), physician assistants (PAs), nurses, registered dietitians (RDs), pharmacists, exercise physiologists, certified fitness trainers, and behavior therapists collaborate to provide tailored advice for individuals encountering weight loss plateaus. Physicians, NPs, and PAs diagnose and manage the medical aspects of weight loss, including addressing hormonal imbalances and prescribing necessary treatments. Nurses are critical in educating patients, monitoring progress, and providing ongoing support. Pharmacists manage medications and advise patients about potential side effects and interactions. Behavior therapists address psychological barriers, implement cognitive behavioral strategies, and assist patients with emotional eating habits. Fitness specialists teach safe aerobic and resistance activities and create individualized exercise regimens for patients experiencing a weight loss plateau. Less costly group-based interventions, led by lifestyle coaches and RDs, can be highly effective, providing peer support and practical advice.

Despite the recognized benefits of such collaboration, research indicates that challenges in availability, referrals, role perception, and communication often limit interprofessional efforts.[36] Effective care coordination involves discussing specific roles, strategies, ethics, and responsibilities. There is no "one-size-fits-all" approach, and healthcare team members must assess patients on a case-by-case basis.[37] By working together and leveraging advancements in research and technology, interprofessional colleagues can support people throughout their weight loss journey and help them overcome weight loss plateaus.