Continuing Education Activity

Weight loss can be achieved through several different strategies. Most people starting a weight loss plan experience rapid weight loss initially. However, they often reach a period where they experience a plateau, and their weight loss appears stagnant. This activity describes the physiology of what happens during a weight loss plateau and strategies to overcome this phenomenon.

Objectives:

• Review the physiology of weight loss.
• Identify different weight loss strategies.
• Explain how and why weight loss plateaus occur.
• Describe strategies used by interprofessional to overcome weight loss plateaus.

Introduction

Weight loss can be accomplished through various strategies, ultimately coming down to a net caloric deficit. Frequently, people who are new to exercising and dieting experience relatively rapid weight loss in the initial few weeks of starting. However, as their bodies adjust, they frequently experience a weight loss plateau that can be frustrating to overcome. In addition, the psychology of seeing a rapid reduction of weight initially and then seemingly remaining stagnant despite efforts to restrict caloric intake can be very frustrating.

Studies comparing different diets have shown that a similar degree of weight loss can be achieved in an 8- to 12-week period as long as a caloric deficit is achieved.[1] However, when looking at individuals in the longer term, 24 weeks and beyond, only about 10 to 20% of those individuals successfully maintain their weight loss.[2] This situation perpetuates a popular phrase called "yo-yo dieting." This phenomenon describes individuals trying a particular diet, losing weight, encountering a plateau, and then regaining weight in frustration due to their perception of the diet failing.

A misconception of beginners attempting to lose weight is that the process is linear. Therefore, one can expect that weight loss will occur more rapidly in the early stages. Still, then in the coming weeks, the weight may stay steady or even slightly increase despite maintaining the established calorie deficit. Understanding why this plateau occurs can help individuals remain consistent with their weight loss efforts and continue progressing instead of regressing. Identifying these challenges and considering various strategies to overcome plateaus will ultimately lead to a greater degree of individuals successfully achieving and maintaining their weight loss in the long term.

Function

Weight loss cannot be achieved without a caloric deficit.[3] There are many ways to accomplish this, and several different diets have become popular over the years in efforts to do so. Some examples include low-carbohydrate diets (ie, the Atkins diet), severe low-carbohydrate with increased fat diets (ie, ketogenic diets), low-fat diets, and Mediterranean diets. These various diets have differences on a macronutrient level, making differences in the total protein, total carbohydrates, and/or total fat levels. Study results have shown long-term effects vary between these diets, and questions are raised on safety and efficacy.[4] The common denominator between the diets is energy expenditure, and the total calorie intake must be less than the calorie output. Aside from calorie changes, weight loss can also be achieved by increasing physical activity, as a sole method or in conjunction with diet.[5]

Several factors are assessed when creating a weight loss plan. One of the first things calculated is the total daily energy expenditure (TDEE), which is largely based on basal metabolic rate (BMR). This is also known as resting energy expenditure (REE). The remaining portion is made up of the non-resting energy expenditure (NREE), which is subdivided into exercise activity thermogenesis (EAT), non-exercise activity thermogenesis (NEAT), and thermic effect of food (TEF). Using TDEE maintenance, calories are calculated, and the total calories per day are calculated to maintain your current weight.[6] Weight loss is accomplished by reducing the maintenance calories into a caloric deficit. A "healthy" number to target for weekly weight loss is about 0.7% of body weight in pounds (lb) per week to maximize fat loss while minimizing metabolic adaptations and muscle loss.[7] In doing so, most diets do not recommend extreme caloric deficits due to safety and long-term efficacy questions.[4]

Delving further into the microscopic level, several hormones play prominent roles concerning energy expenditure. Two hormones directly linked to hunger are leptin and ghrelin. High levels of leptin are associated with satiety and energy expenditure. Ghrelin elevations are related to hunger and stimulating appetite. Triiodothyronine (T3) elevations are related to metabolic rate. Insulin regulates macronutrient metabolism and inhibits muscle protein breakdown.[8] There are many theories as to why weight loss plateaus occur. One popular theory is the "set point" theory. This theory suggests biological control of body weight is regulated by feedback loops from peripheral organs and tissue, such as leptin secretion from adipose tissue, back to the central nervous system to rebalance and maintain homeostasis. Another theory is a "settling point," which reflects metabolic adaptations to energy imbalance without specific feedback control.[9] 

Several studies confirm this phenomenon exists, and more research is needed to understand better why exactly on a micro-level. A leading theory on the biological level is that BMR decreases when you lose weight; lowering the TDEE is a greater amount than expected relative to the loss of body mass.[8] This lowering of TDEE is referred to as adaptive thermogenesis, decreasing energy expenditure to match the lower caloric intake dietarily, thus halting or decreasing the rate of weight loss. On a metabolic level, a series of chemical reactions occur to derive ATP. This process involves uncoupling proteins (UCPs), where energy substrate oxidation occurs along with oxygen consumption. This process contributes to energy expenditure and is thought to be a considerable portion of BMR. Hormonally, anabolic, anorexigenic, and thermogenic hormones are decreased with decreased energy intake, while orexigenic and catabolic hormones are increased. Ultimately this leads to decreased energy expenditure and increased hunger.[8]

Issues of Concern

To achieve weight loss, people reach a point where their energy expenditure is lower than it used to be. Research shows that people who lose weight secrete higher levels of ghrelin, a hormone known to increase hunger, the opposite of the effect of the hormone leptin involved in satiety. These hormones can also impact and increase fatigue.[10][11] Studies have shown an increase in ghrelin also promotes the conservation of fat stores.[12] The combination of increased hunger, increased fatigue, and stalling in weight loss can be very discouraging for people, leading them to quit their diet. Not only is the diet terminated, but the increase in hunger often leads to regaining weight. The weight loss plateau period can be an important period where hormone levels and metabolic rates are readjusted.[13]

Being mindful of the hormonal and psychological impact of this plateau is essential. If weight loss is not accomplished in a calculated manner, a large amount of lean mass may be lost compared to fat loss. An increase in hunger and an increase in ghrelin can cause rapid weight gain. Although an individual may return to their original starting weight, they could have more fat and less muscle mass than starting if weight loss is not accomplished in a safe calculated way. This can lead to a detrimental effect where hunger levels increase, fatigue increases, weight is regained, and individuals are left feeling worse psychologically and gain weight compared to their starting point.

Clinical Significance

Understanding the weight loss process and where an individual may be in that journey is vital. If someone complains of worsening fatigue and has lost a large amount of muscle mass, they may need a "recovery phase" to increase or regain lost muscle mass. An increase in lean muscle mass has a positive impact on improving metabolism.[14] This recovery phase of eating an increased amount of calories can also, in turn, decrease hunger levels, improve energy, and restore alterations in hormonal levels from a severe calorie deficit. On an endocrine level, energy restrictions lead to decreased leptin levels, decreased insulin, testosterone, thyroid hormones, and increased ghrelin and cortisol.[8] This occurs due to a shift in homeostasis due to energy unavailability, leading the body to adapt in an effort to promote energy intake and cessation of energy expenditure. 

Another factor to consider is non-exercise activity thermogenesis (NEAT). NEAT is the energy expended from daily activities throughout the day, such as walking to work, typing, and even fidgeting.[15] A study was conducted testing 16 individuals over an eight week period. These individuals were fed an additional 1000 calories per day. One may expect each person to gain about 16 pounds at the end of this period. However, results varied drastically from individual to individual, as results ranged from less than 1 pound gained to about 9 pounds gained.[16] This suggests that although humans overeat, the actual weight gain varies due to NEAT dissipating excess energy to preserve leanness.

Enhancing Healthcare Team Outcomes

Understanding the stages of weight loss is vital for both healthcare providers and patients as it can be easy to become frustrated throughout the process and one may fail to reach their goals, particularly during a weight loss plateau period. Unfortunately, research has no clear indication of how long this period can last, ranging from weeks to even months. Many challenges can occur during this process, including hormonal changes and psychological impact. Interprofessional teams, including a physician, a dietitian, and a psychologist, can be very beneficial in understanding the process better and educating patients through their journey. Although it may be recognized that these specialists may be able to assist, research has shown that this does not occur often enough. A study was conducted showing challenges in interprofessional availability, the number of referrals, role perception, and messaging.[17] Studies have shown that an interprofessional approach can be effective in weight loss. However, there is no "one-size-fits-all" approach.[18] Individuals need to be assessed on a case-by-case basis, depending on where they are in their weight loss journey. As a whole, awareness should improve amongst healthcare professionals in understanding weight loss as research and technologies advance.