Fundamentals of Nutrition, Calorie Balance, and Body Weight. -
Weight management and obesity prevention are two of the hottest topics in health and nutrition today. Clinicians from virtually every medical field seek information on these topics, in part, because of the vast number of patients who have an abnormal or undesirable weight status. This chapter will provide an overview of calorie balance and the macronutrients that contribute to energy intake.
Calorie Balance -
Body weight is primarily determined by a simple concept known as energy balance. Energy balance is the ratio of energy ingested through foods and beverages to the energy expended through basal metabolism, the therms effect of food, and physical activity.
The energy discussed in nutrition and weight management is measured in kilocalories (kcal). One kcal is defined as the amount of heat, or energy, necessary to raise 1 kg of water by 1 °C. Although the scientifically correct term for this energy is kcal, most consumer-facing and educational resources refer to this energy as simply calories.
Energy ingested -
Energy or calories, ingested by human beings comes from four macronutrients: carbohydrate, fat, protein, and alcohol. Based on its corresponding chemical structure, each of these macronutrients will provide a particular level of energy, or calories, per gram ingested. Carbohydrates and protein are the least energy-dense, of the macronutrients, providing ~4 kcal/g. Alcohol provides 7 kcal/g. Fat is the most energy-dense, providing ~9 kcal/g. The caloric content of foods and beverages is based on the grams of carbohydrate, fat, protein, and alcohol in the associated product. For example, if a food’s nutrition facts label states that it has 25 g of carbohydrate (CHO), 1 g of fat (FAT), 1 g of protein (PRO), and no alcohol per single serving, then one serving of that food should have ~113 kcal (although, due to the rounding off some of these number, the label may state that the caloric content is slightly higher or lower than this number). Performed in the examples above may be slightly different from the numbers appearing on the label itself. In addition, the labeling rules for alcohol-containing products are different from nonalcoholic products; therefore, traditional nutrition facts labels may not be available on all alcohol-containing products.
Carbohydrates -
Carbohydrates and Carbohydrate-containing foods are extremely important to the American diet. In general, most Americans consume plenty of carbohydrates each day; however, the types of carbohydrate-containing foods Americans typically eat are not considered to be ideal. As such, when discussing weight management and obesity prevention, it is imperative to discuss carbohydrates and carbohydrate-containing foods in order to better understand what dietary modifications should be made.
Chemically speaking, carbohydrates are made up of single or strands of carbon rings, called saccharine polymers. These polymers take on four different forms: a single saccharine polymer (monosaccharides), two polymers attached to each other (disaccharides), three to nine polymers in a single strand (oligosaccharides), or ten or more polymers in a single strand (polysaccharides). Monosaccharide and disaccharide polymers are commonly referred to as simple carbohydrates or simple sugars. Monosaccharide polymers include the most elemental forms of carbohydrate found in nature: glucose, galactose, and fructose. Disaccharide polymers are made up of two monosaccharide polymers joined together, and the three disaccharides are sucrose (glucose + fructose), lactose (glucose + galactose), and maltose (glucose + glucose).
On the nutrition facts label, the monosaccharide and disaccharide content of food will be indicated on the rows labeled “Total Sugars.” It is important to note that total sugars include both the naturally occurring simple sugars (e.g., lactose in milk) and added sugars that are incorporated during food processing (e.g., high fructose corn syrup in ketchup). Future labeling regulations may require manufacturers to distinguish between natural and added sugars, but as of the writing of this book, the current nutrition facts label combines these two sugars.
Oligosaccharide and polysaccharide polymers contain three or more monosaccharide units; thus, they are referred to as complex carbohydrates. Oligosaccharides, which contain three to nine monosaccharide polymers, are commonly found in legumes. Polysaccharides, the longest chains of saccharine polymers, are often called starch and are commonly found in starchy vegetables (e.g., potatoes and peas) and grains (e.g., bread, pasta, and rice).
According to the Institute of Medicine’s Dietary Reference Intakes, carbohydrates should make up about 45 to 65 percent of the calories in the diet. Healthy adults should consume a minimum of 130 g of carbohydrates per day, although there are some lower-carbohydrate diets that discourage carbohydrate consumption at this level.
Fats -
Dietary fats are an essential component of any healthy diet. Although dietary Fats gained a negative connotation in the 1990s and early 2000s, researchers have shown fat to be a key element in weight management. Fat is known as one of the dietary components that lead to satiety, or feelings of fullness after a meal. Fat also contributes to food’s palatability and desirable texture. Nonetheless, when talking about fat, clinicians should realize that not all fats are created equal. Some fats appear to have more health consequences than others. As such, patients should be careful and primarily focus on consuming healthier fats.
Protein -
Protein, the third essential macronutrient, is essential for building new body tissue. Like the proteins found in the body, dietary proteins are made up of long chains of amino acids, also called polypeptides. There are 20 amino acids that make up these polypeptides. While all amino acids are structurally similar, the differentiating characteristic is each amino acid’s unique side group. Amino acids fall into one of three categories: essential, nonessential, and conditionally essential. Essential amino acids are ones that cannot be synthesized in the human body, and therefore, must be ingested through the diet.
Epidemiology and Health Consequences of Obesity -
The prevalence of overweight and obesity among industrialized nations such as the United States has been increasing over the past several decades. In turn, this has led to higher rates of chronic disease and increased health care costs. Clinicians must understand the epidemiology of overweight and obesity in order to properly articulate the associated risks of these conditions. This chapter will focus on the history of the current American obesity epidemic, its associated health consequences, and how it is impacting the lives of those diagnosed with these conditions.
Factors Contributing to Overweight and Obesity -
As described in the previous chapter, the epidemic of overweight and obesity has escalated over the past several decades, yet a single cause of obesity has never been elucidated. There is probably no single cause of this epidemic. Instead, it is widely accepted that the obesity epidemic has arisen from a myriad of contributing factors, including those which originate at the individual, interpersonal, and environmental levels. Using a social Economical model as the guiding framework, this chapter will describe these contributing factors and will explain how these factors relate to the accumulation of excessive weight.
Nutrition Assessment -
The first step in the nutritional management of a patient seeking weight guidance is a full nutrition assessment. Nutrition assessment typically involves the evaluation of anthropometric measurements, biochemical data, and physical signs and symptoms, as well as a thorough interview with the patient. This chapter will review each of these aspects of nutrition assessment and explain how they can inform the rest of the weight management program
Weight Loss Intervention: Program Characteristics and Components -
A comprehensive weight management program, will exhibit a myriad of characteristics and include many components that have the potential to impact a patient’s success. In this chapter, program characteristics and components will be explored using a who/what/when/where approach.
The “Who” Component: Who Should Be Involved? -
The first major component of a weight management program is the people involved in the program. Although the patient and clinicians are the primary individuals involved, family and friends who provide social support should also be included if the patient consents to their involvement.
Weight Loss Intervention: Goal Setting -
Once a patient has been assessed and decides to enter a weight management program, goals for achieving a healthier body weight should be set. This chapter will discuss goal setting in the context of an entire weight management program, as well as from an individual patient perspective.
Overarching Goals of Weight Management Programs -
Although most patients will seek weight management guidance because they (or their clinicians) dislike the number appearing on the scale, it is important that their weight not be the only goal of a weight management program. Just as health is measured in a variety of ways, success in a weight management program should also be measured using more than one approach.
The first overall goal of a weight management program is curtailing weight gain and preventing future weight gain (Sea gal et al. 2009, 330–46). Most individuals entering a weight management program have been slowly gaining weight over the course of several months or years; thus, the first goal is to stop this trend from continuing. Many patients may not feel successful if they simply maintain their weight while in a program, but it is the clinician’s duty to articulate the value of maintaining weight while establishing healthy habits.
The second and most obvious goal of a weight management program is the loss of body weight (Sea gal et al. 2009, 330–46). Weight loss should be achievable through healthy, maintainable behaviors (i.e., without extreme dieting or restriction) and should primarily result from the loss of body fat. In order to achieve weight loss, calorie needs must be assessed, and realistic caloric goals must be set. These two concepts will be discussed later in this chapter.
Weight Loss Intervention: Energy and Macronutrient Approaches to Calorie Reduction -
Weight loss programs must focus on helping patients achieve negative energy balance, but in order to achieve this imbalance, several approaches can be used. In this chapter, three common approaches to adult weight management will be described, and the benefits and challenges associated with each approach will be explored. The final section will focus on macronutrient recommendations for pediatric weight management.
Weight Loss Intervention: Basic Concepts for Nutrition Education -
Without basic nutrition knowledge, an individual may struggle to effectively manage his weight. As such, it is imperative that key concepts be conveyed through basic nutrition education as part of a comprehensive weight management program. This chapter will explore some of these key concepts and will also provide examples of how these concepts can be incorporated into the program.
Empty Calorie Foods -
In a comprehensive weight management program, one of the most basic concepts that should be conveyed during the first nutrition education session is the concept of empty calories and empty calorie foods. Empty calories are essentially the calories contributed by solid fats and added sugars, which add little to no nutritional value to the diet. Empty calorie foods are calorie-containing foods and beverages, which tend to be high in solid fats and added sugars, and have few nutrients, antioxidants, or phytochemicals. In essence, the calories consumed from these foods are not nutrient-dense and, therefore, provide minimal health benefits.
Because individuals seeking weight management will need to limit the number of calories they consume, they will need to ensure that all the foods and beverages they eat are as nutrient-dense as possible; therefore, they should limit the number of empty calories and empty calorie foods they eat and drink on a daily basis.
Weight Loss Intervention: Behavior Modification -
Dietary intake is a deeply engrained and extremely complex human behavior. As such, modifying this behavior can be challenging, and it may take several months (or even years) to establish new dietary habits. In this chapter, strategies for modifying dietary behaviors will be explored and examples for using these strategies will be discussed.
Self-Monitoring -
There is strong evidence supporting the role of self-monitoring in modifying and improving dietary behaviors among adult (Academy of Nutrition and Dietetics 2014) and pediatric (Academy of Nutrition and Dietetics 2007, 11) patients who are trying to lose weight. Self-monitoring activities include having a patient document everything he eats and drinks during the day in a paper or electronic logbook. Self-monitoring activities can also include documenting where he consumes his meals, what time he consumes his meals, and how he is feeling at the time of consumption.
Self-monitoring can then be used as a tool for reflection. For example, if a patient logs everything he eats for a week, then he and the clinician can review the logbook at their visit and identify trends. The patient may notice that he tends to eat empty-calorie foods in the evening when he is tired and is watching television, or he may notice that he eats fast food more often than he originally thought. Self-monitoring logs can be analyzed for nutrient and food content by the Registered Dietitian Nutritionist (RDN). Findings from this kind of analysis should be shared with the patient and used to modify the meal plan.
Weight Loss Intervention: Medications -
Individuals who are unable to lose weight through dietary modifications and physical activity may add prescription medications to their weight loss plan. Although most of these medications must be prescribed by authorized providers, they can further assist in some aspects of appetite and weight control; however, side effects and the duration of treatment must be carefully considered prior to initiate pharmacotherapy. This chapter will discuss the various types of medications that can assist with weight loss, how they achieve weight loss and their potential side effects. (Please note that the medications discussed in this chapter should only be prescribed by physicians or clinicians with the appropriate order-writing privileges. This chapter is intended to serve as an overview of popular weight loss medications; however, it is not a substitute for the full prescribing information that is available through the manufacturer.)
Weight Loss Intervention: Weight Loss Surgery -
In some cases, it may be appropriate for a patient to undergo weight loss or bariatric, surgery in order to achieve a more desirable body weight. In the United States, ~193,000 weight loss surgeries were performed in 2014 alone (American Society for Metabolic and Bariatric Surgery 2015), a number that has been on the rise over the years. In this chapter, the indications for weight loss surgery and the pre-and postoperative nutritional management of these surgical patients will be explored, and four types of weight loss surgery will be discussed.
Physical Activity -
Although most of this textbook has focused on the energy intake side of the energy balance equation, all weight management programs should also emphasize the energy output (or energy expenditure) side of the equation. The energy output is consisting of multiple factors (i.e., basal metabolism, physical activity, and the etheric effect of food); however, physical activity is the most significant because it is the easiest to modify. This final chapter will discuss physical activity in the context of weight management for both adult and pediatric patients.
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