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19.3: Weight Loss - Diets and Exercise

  • Page ID
    152261
  • Learning Objective

    • Learn about various recommendations for weight loss and weight management.

    With over 70 percent of Americans currently overweight or obese, it isn’t surprising that many individuals report engaging in weight management efforts. 1 In fact, a 2019 report from a national survey on current trends in weight loss attempts and strategies found that 42 percent of adults in the United States had recently attempted to lose weight, primarily through reduced food consumption and exercise.

    The National Weight Control Registry (NWCR) has tracked over ten thousand people who have been successful in losing at least 30 pounds and maintaining this weight loss for at least one year. Their research findings show that 98 percent of participants in the registry modified their food intake, and 94 percent increased their physical activity, mainly by walking. 

    Although there were a great variety of approaches taken by NWCR members to achieve successful weight loss, most have reported that their approach involved adhering to a low-calorie, low-fat diet and doing high levels of activity (about one hour of exercise per day). Moreover, most members eat breakfast every day, watch fewer than ten hours of television per week, and weigh themselves at least once per week. About half of them lost weight on their own, and the other half used some type of weight-loss program. 11 In most scientific studies, successful weight loss is accomplished only by changing the diet and increasing physical activity together. Doing one without the other limits the amount of weight lost and the length of time that weight loss is sustained. 

    Evidence-Based Dietary Recommendations

    The 2015 Dietary Guidelines for Americans offers specific, evidence-based recommendations for dietary changes aimed at keeping calorie intake in balance with physical activity, which is key for weight management. These recommendations include:

    Follow a healthy eating pattern that accounts for all foods and beverages within an appropriate calorie level that includes:

    • A variety of vegetables from all of the subgroups—dark green, red and orange, legumes (beans and peas), starchy, and other
    • Fruits, especially whole fruits
    • Grains, at least half of which are whole grains
    • Fat-free or low-fat dairy, including milk, yogurt, cheese, and/or fortified soy beverages
    • A variety of protein foods, including seafood, lean meats and poultry, eggs, legumes (beans and peas), and nuts, seeds, and soy products
    • Oils

    A healthy eating pattern limits:

    • Saturated fats and trans fats
    • Added sugars
    • Sodium

    Key quantitative recommendations are provided for several components of the diet that should be limited. These components are of particular public health concern in the United States, and the specified limits can help individuals achieve healthy eating patterns within calorie limits[5]:

    • Consume less than 10 percent of calories per day from added sugars
    • Consume less than 10 percent of calories per day from saturated fats
    • Consume less than 2,300 milligrams (mg) per day of sodium

    If alcohol is consumed, it should be consumed in moderation—up to one drink per day for women and up to two drinks per day for men—and only by adults of legal drinking age.

    Dietary Food Trends

    In the past, health was regarded merely as the absence of illness. However, a growing understanding of the complexity and potential of the human condition has prompted a new way of thinking about health. Today, we focus on the idea of wellness, which involves a great deal more than just not being sick. Wellness is a state of optimal well-being that enables an individual to maximize their potential. This concept includes a host of dimensions—physical, mental, emotional, social, environmental, and spiritual—which affect one’s quality of life. Striving for wellness begins with an examination of dietary choices.

    Hundreds of years ago, when food was less accessible and daily life required much more physical activity, people worried less about obesity and more about simply getting enough to eat. In today’s industrialized nations, conveniences have solved some problems and introduced new ones, including the hand-in-hand obesity and diabetes epidemics. Fad diets gained popularity as more North Americans struggled with excess pounds. However, new evidence-based approaches that emphasize more holistic measures are on the rise. These new dietary trends encourage those seeking to lose weight to eat healthy, whole foods first, while adopting a more active lifestyle. These sound practices put dietary choices in the context of wellness and a healthier approach to life.

    Functional Foods

    Many people seek out foods that provide the greatest health benefits. This trend is giving rise to the idea of functional foods, which not only help meet basic nutritional needs but also are reported to fight illness and aging. According to the Academy of Nutrition and Dietetics (AND), formerly known as the The American Dietetic Association, functional foods may reduce the risk of disease or promote optimal health. The AND recognizes four types of functional foods. They are: conventional foods, modified foods, medical foods, and special dietary use foods.

    The first group, conventional foods, represents the simplest form of functional foods. They are whole foods that have not been modified. Examples include whole fruits and vegetables (which are abundant in phytochemicals and antioxidants), yogurt and kefir (which contain natural probiotic bacteria that can help maintain digestive system health), and moderate amounts of dark chocolate, made with 70% or more cacao (which contains antioxidants).

    Modified foods have been fortified, enriched, or enhanced with additional nutrients or bioactive compounds. Foods are modified using biotechnology to improve their nutritional value and health attributes. Examples of modified foods include calcium-fortified orange juice, breads enriched with B vitamins, iodized salt, cereals fortified with vitamins and minerals, margarine enhanced with plant sterols, and energy drinks that have been enriched with herbs (ginseng or guarana) or amino acids (taurine). It is important to consider that the health claims of some modified foods may be debatable, or entirely fraudulent. Check with a health professional regarding the effects of modified foods on your health.

    Medical foods are designed for enteric administration under the guidance of a medical professional. (During enteric administration, food is treated so that it goes through the stomach undigested. Instead, the food is broken down in the intestines only.) Medical foods are created to meet very specific nutritional requirements. Examples of medical foods include liquid formulas for people with kidney disease, liver disease, diabetes, or other health issues. Medical food is also given to comatose patients through a gastronomy tube because they cannot eat by mouth.

    Special dietary use foods do not have to be administered under a doctor’s care and can be found in a variety of stores. Similar to medical foods, they address special dietary needs and meet the nutritional requirements of certain health conditions. For example, a bottled oral supplement administered under medical supervision is a medical food, but it becomes a special dietary use food when it is sold to retail customers. Examples of special dietary use foods include gluten-free foods, lactose-free dairy products, and formulas and shakes that promote weight loss.

    Popular Diets

    The concept of functional foods represents initiatives aimed at addressing health problems. Certain diet plans take this concept one step further, by striving to prevent or treat specific conditions. For example, it is widely understood that people with diabetes need to follow a particular diet. Although some of these diet plans may be nutritionally sound, use caution because some diets may be fads or be so extreme that they actually cause health problems.

    Before experimenting with a diet, discuss your plans with your doctor or a registered dietitian. Table \(\PageIndex{1}\) lists the pros and cons of the more popular diets. Some fall under the category of fad diets, while others are backed by scientific evidence. Those that fall into the latter category provide a good foundation to build a solid regimen for optimal health.

    Table \(\PageIndex{1}\) The Pros and Cons of Seven Popular Diets.
    Diet Pros Cons
    DASH Diet

    Recommended by the National Heart, Lung, and Blood Institute, the American Heart Association, and many physicians

    Helps to lower blood pressure and cholesterol

    Reduces risk of heart disease and stroke

    Reduces risk of certain cancers

    Reduces diabetes risk

    There are very few negative factors associated with the DASH diet

    Risk for hyponatremia

    Gluten-Free Diet

    Reduces the symptoms of gluten intolerance, such as chronic diarrhea, cramping, constipation, and bloating

    Promotes healing of the small intestines for people with celiac disease, preventing malnutrition

    May be beneficial for other autoimmune diseases, such as Parkinson’s disease, rheumatoid arthritis, and multiple sclerosis

    Risk of folate, iron, thiamin, riboflavin, niacin, and vitamin B6 deficiencies

    Special gluten-free products can be hard to find and expensive

    Requires constant vigilance and careful food label reading, since gluten is found in many products

    Low-Carb Diet

    Restricts refined carbohydrates, such as white flour and white sugar

    May temporarily improve blood sugar or blood cholesterol levels

    Not entirely evidence-based

    Results in higher fat and protein consumption

    Does not meet the RDA for carbohydrates to provide glucose to the brain

    Macrobiotic Diet

    Low in saturated fats and high in fiber

    Emphasizes whole foods and de-emphasizes processed foods

    Rich in phytoestrogens, which may reduce the risk of estrogen-related cancers

    Not entirely evidence-based

    Lacks certain vitamins and minerals; supplements are often required

    Can result in a very low caloric intake

    Lack of energy may result from inadequate protein

    Mediterranean Diet

    A reduced risk of cardiovascular disease and mortality

    A lower risk of cancer

    De-emphasizes processed foods and emphasizes whole foods and healthy fats

    Lower sodium intake, due to fewer processed foods

    Emphasis on monosaturated fats leads to lower cholesterol

    Highlighting fruits and vegetables raises consumption of antioxidants

    Does not specify daily serving amounts

    Potential for high fat and high calorie intake as nuts and oils are calorie-dense foods

    Drinking one to two glasses of wine per day may not be healthy for those with certain conditions

    Raw Food Diet

    Emphasizes whole foods

    Focuses on nutritionally-rich foods

    Not entirely evidence-based

    Very restrictive and limits protein and healthy fat intake

    Could encourage the development of foodborne illness

    Extremely difficult to follow

    High in fiber which can cause essential nutrient deficiencies

    Vegetarianism and Veganism

    May reduce some chronic diseases such as cancer, heart disease, and Type 2 diabetes

    May help with weight reduction and weight maintenance

    Guidelines regarding fat and nutrient consumption must be followed

    Higher risk for nutrient deficiencies such as protein, iron, zinc, omega-3, vitamin B12

    Consumption of a high fiber diet interferes with mineral and nutrient bioavailability

    Vegetarian and vegan protein sources are lower quality with majority missing at least one essential amino acids

    Evidence-Based Physical Activity Recommendations

    The other part of the energy balance equation is physical activity. The Dietary Guidelines are complemented by the 2018 Physical Activity Guidelines for Americans, issued by the Department of Health and Human Services (HHS) in an effort to provide evidence-based guidelines for appropriate physical activity levels. These guidelines provide recommendations to Americans aged three and older about how to improve health and reduce chronic disease risk through physical activity. Increased physical activity has been found to lower the risk of heart disease, stroke, high blood pressure, Type 2 diabetes, colon, breast, and lung cancer, falls and fractures, depression, and early death. Increased physical activity not only reduces disease risk, but also improves overall health by increasing cardiovascular and muscular fitness, increasing bone density and strength, improving cognitive function, and assisting in weight loss and weight maintenance. 

    The key guidelines for adults include the following:

    • Adults should move more and sit less throughout the day. Some physical activity is better than none. Adults who sit less and do any amount of moderate-to-vigorous physical activity gain some health benefits.
    • For substantial health benefits, adults should do at least 150 minutes (2 hours and 30 minutes) to 300 minutes (5 hours) per week of moderate-intensity aerobic activity, or 75 minutes (1 hour and 15 minutes) to 150 minutes (2 hours and 30 minutes) per week of vigorous-intensity aerobic physical activity, or an equivalent combination of moderate- and vigorous-intensity aerobic activity .
    • Preferably, aerobic activity should be spread throughout the week.
    • Engaging in physical activity beyond the equivalent of 300 minutes (5 hours) of moderate-intensity physical activity per week can result in additional health benefits and may help with weight loss and weight loss maintenance.
    • Adults should also do muscle-strengthening activities of at least moderate intensity that involve all major muscle groups on 2 or more days per week, as these activities provide additional health benefits . Exercises such as push-ups, sit-ups, squats, and lifting weights are all examples of muscle-strengthening activities.

    The 2018 Physical Activity Guidelines broadly classify moderate physical activities as those when you “can talk, but not sing, during the activity” and vigorous activities as those when you “cannot say more than a few words without pausing for a breath.” 14 Despite the indisputable benefits of regular physical activity, a 2018 report from the American Heart Association estimates that 8 out of 10 Americans do not meet these guidelines. 2

    19A4.jpg

    Figure \(\PageIndex{1}\) The 2018 Physical Activity Guidelines’ definition of moderate-intensity and vigorous-intensity exercise.

    Given the number of Americans that are falling short on both nutrition and physical activity recommendations, it is easy to see that these two areas of behavior are of primary interest in improving the health and weight of our nation.

    Evidence-Based Behavioral Recommendations

    Behavioral weight loss interventions have been described as approaches “used to help individuals develop a set of skills to achieve a healthier weight. It is more than helping people to decide what to change; it is helping them identify how to change.”  Cornerstones for these interventions typically include self-monitoring through daily recording of food intake and exercise, nutrition education and dietary changes, physical activity goals, and behavior modification.  Research shows that these types of interventions can result in weight loss and a lower risk for type 2 diabetes, and similar maintenance strategies lead to less weight regained later.

    Behavioral interventions have been shown to help individuals achieve and maintain weight loss of at least 5 percent from baseline weight. The Food and Drug Administration (FDA) considers a 5 percent weight loss to be clinically significant, as this level of weight loss has been shown to improve cardiometabolic risk factors such as blood lipid levels and insulin sensitivity. 17,18 The behavioral intervention team often includes primary care clinicians, dietitians , psychologists, behavioral therapists, exercise physiologists, and lifestyle coaches. These programs may include a variety of delivery methods, often through group classes of 10-20 participants both in-person and online, and may use print-based or technology-based materials and resources. The interventions usually span one to two years with more frequent contact in the initial months (weekly to bi-monthly) followed by less frequent contact (monthly) in the latter months, or maintenance phase.17 A variety of behavioral topics are covered over the course of the program and range from nutrition education and goal-setting to problem-solving and assertiveness. Relapse prevention is included as participants move into the maintenance phase.

    19A5.jpg

    Figure \(\PageIndex{2}\), Common topics included in behavioral interventions for weight loss, adapted from Smith, C. E., & Wing, R. R. (2000). New directions in behavioral weight-loss programs. Diabetes Spectrum, 13(3), 142-148.

     

    Summary

    • The 2015 Dietary Guidelines for Americans offers specific, evidence-based recommendations for dietary changes aimed at keeping calorie intake in balance with physical activity, which is key for weight management.
    • These new dietary trends encourage those seeking to lose weight to eat healthy, whole foods first, while adopting a more active lifestyle. These sound practices put dietary choices in the context of wellness and a healthier approach to life.

     

    • Increased physical activity not only reduces disease risk, but also improves overall health by increasing cardiovascular and muscular fitness, increasing bone density and strength, improving cognitive function, and assisting in weight loss and weight maintenance. 
    • Behavioral interventions have been shown to help individuals achieve and maintain weight loss of at least 5 percent from baseline weight.

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