Maintaining a Healthy Weight
Numerous methods can be used to maintain a healthy weight or to lose weight when necessary. Fitness professionals should encourage clients to choose weight maintenance or weight-loss techniques that are effective yet pose little threat to overall health. The following sections outline practices that most adults can implement safely.
Assessing Daily Caloric Need
Whether planning individualized programs for weight loss or weight maintenance, it is helpful to know the number of calories the client needs to sustain her current body weight. You can gain this knowledge by estimating daily caloric need. Daily caloric need is the number of calories a person needs to sustain current body weight, assuming that activity levels remain constant. The resting metabolic rate, thermic effect of food, and energy consumed by daily activities determine the daily caloric need (figure 12.2).
Resting metabolic rate (RMR) is the number of calories expended to maintain the body during resting conditions. For most people, RMR is 60% to 70% of their daily caloric need. For people who engage in regular, vigorous exercise, the RMR may account for a smaller proportion of daily caloric need because the energy requirements of exercise account for a larger percentage. RMR can be measured in a laboratory using indirect calorimetry. To accurately measure RMR, assess the client when he has not eaten for several hours, has not exercised vigorously for the past 12 hr, and has been in a resting, reclined position for 30 min (28). Because of the cost of indirect calorimetry and the strict control needed to obtain accurate results, measuring RMR is not always practical; therefore, a number of equations have been developed to predict RMR. These RMR equations are based on the following principles:
- RMR is proportional to body size.
- RMR decreases with age.
- Muscle is more metabolically active than fat.
The larger the body, the more calories needed to sustain it. This relationship is reflected in all RMR equations. In addition to body size, age significantly affects RMR. As a person ages, RMR decreases, meaning that the daily caloric need decreases with age. Generally RMR equations are sex-specific because males often have more fat-free mass than females have and fat-free mass requires more energy compared with fat tissue.
If a client’s fat-free mass is known, the following equation can be used to predict RMR (9). There is no need for sex-specific equations when fat-free mass is known, because a gram of muscle has the same metabolic need whether it resides in a male or female body.
RMR (kcal · day−1) = 370 + (21.6 · fat-free mass in kg).
When determining daily caloric need, an estimate of the calories burned in physical activity is needed. This assessment requires information about work and leisure activity. Although there are numerous ways to gather information about daily activity, one typical method is an activity log in which the client records work and leisure activity. Once the activity pattern is established, the caloric cost of various activities can be calculated (see chapter 6) and used to estimate the energy burned in activity. Estimating this energy is especially important if working with a client who trains extensively. Alternatively, you can estimate daily caloric need by using the methods outlined in Calculating Daily Energy Needs.
The smallest part of the daily caloric need comes from the thermic effect of food. This is the energy needed to digest, absorb, transport, and store the food that is eaten. Although this value may vary slightly depending on the food eaten, the thermic effect of food typically accounts for 10% of the daily caloric need (29).
Changing Lifestyle to Promote a Healthy Weight
Although each individual must assess which areas of her lifestyle contribute to excessive weight accumulation, common steps that benefit the majority of people who are attempting to lose weight include the following:
- Reduce total calories.
- Reduce fat intake.
- Increase physical activity.
- Change eating behaviors.
As previously mentioned, a negative caloric balance must be established for weight loss. The number of calories consumed while attempting to lose weight should be determined by the client’s health, caloric need, and ultimate weight-loss goals. Most healthy adults who need to lose weight can institute a short-term low-calorie diet (LCD) consisting of 800 to 1,500 kcal · day−1 without major adverse consequences. Very low-calorie diets (VLCDs) are sometimes used in specialized settings to treat individuals with extreme obesity. In these cases, physicians and dietitians provide patient oversight. VLCDs can lead to substantial weight loss, and years of study with this approach has yielded protocols with few negative side effects (39).
ACSM recommends that weekly weight-loss goals should target a loss of 1 to 2 lb or 0.5 to 0.9 kg (1). A general guideline is to establish a caloric deficit of 3,500 to 7,000 kcal · wk−1 (500-1,000 kcal · day−1), which theoretically results in a 1 to 2 lb loss (0.5 to 0.9 kg) of fat each week (1 lb of fat = 3,500 kcal). ACSM also recommends that people restricting their caloric intake limit their fat intake to less than 30% of total calories (1). These are general recommendations, and people with special needs (e.g., athletes, older adults, people with metabolic disorders) may require a different approach to weight loss. Caloric restriction can lead to decreased RMR and fat-free mass. The decrease in RMR and loss of fat-free mass will be greater in dieters with large daily caloric deficits (31).
Exercise Prescription for Weight Management
ACSM recommends a combined approach of exercise and moderate caloric restriction for people attempting weight loss (1, 2). Although debate continues over the precise contribution of exercise to weight management, a combination of exercise and moderate calorie restriction appears to be most effective in maintaining lean mass and avoiding excessive decreases in RMR. Existing data clearly demonstrate that people who are successful in maintaining weight loss engage in regular aerobic activity (44). Studies also show that regular exercise helps prevent weight gain (10, 16, 21). From a theoretical perspective, adding exercise to everyday life can significantly alter body weight. For example, expending just 100 kcal · day−1 beyond daily caloric need for a year creates a caloric deficit of 36,500 kcal. ACSM recommends that individuals engage in a minimum of 150 min of moderate-intensity exercise per week and further states that additional exercise (200-300 min · wk−1) is more likely to be associated with successful weight control (1, 2). The following are specific recommendations for weight loss with exercise (1):
- Frequency: 5 to 7 days · wk−1.
- Intensity: initially moderate (40%-60% HRR), then progressing to higher intensity (50%-75% HRR).
- Duration: progress from short, easily tolerated bouts to 45 to 60 min daily. Multiple daily bouts can be used with bout duration of 10 min or longer.
- Type: aerobic exercise targeting large muscle groups. Resistance exercise is recommended as a supplement to aerobic activity.
In addition to the physical benefits, psychological variables improve with exercise. Improvements in self-esteem and self-efficacy are commonly reported outcomes of regular exercise. The empowerment that comes from becoming more fit can add to the resolve to live a healthy lifestyle and maintain a healthy weight.
Behavior Modification for Weight Loss and Maintenance
The majority of attempts to lose weight and maintain weight loss are unsuccessful. Behavior modification (changes in lifestyle habits) is an important component of successful weight-loss and maintenance programs (31). For additional information on behavior modification, see chapter 23.
When people are committed to changing eating and activity patterns, a number of strategies can improve the chances of long-term success. During the initial phase of weight loss (the action stage; see chapter 23), implementing these strategies requires a great deal of effort and there is a significant chance of failure (i.e., relapse). After 6 mo or more of using these strategies (the maintenance stage; see chapter 23), changes in diet and lifestyle become more natural. Some strategies effective for losing weight and maintaining weight loss are discussed next. Not every person responds well to the same techniques, so clients should be considered separately and an individualized plan developed for each.
Before implementing a weight-loss or maintenance program, it is wise to examine current eating patterns. This is most easily done with an eating diary or food log. A sample food log is provided in chapter 5. Remember, it is important to gather information about the types and quantities of food eaten as well as the social and emotional circumstances surrounding eating.
Careful record keeping accomplishes several objectives. First, food logs document the problem areas of food intake. Many people are unaware of the total calories or the amount of fat they consume daily. Second, eating diaries document the social and emotional cues to eating. After keeping records for a while, individuals begin to recognize the factors other than hunger that lead to eating (e.g., socializing with friends, watching television, feeling stressed). To combat these cues to eating, the social and emotional situations that trigger overeating must be recognized and strategies developed to overcome them. Third, recording food intake makes eating a cognitive process. For many people, eating is a habit, and they automatically choose how much and what to eat without conscious consideration. As discussed next, planning appropriate meals and snacks is an important component of successful weight loss.
Planning Meals and Snacks
Weight loss does not occur by accident; it takes a concerted effort. Purchasing appropriate foods and planning meals are imperative for success. One of the most helpful practices in controlling food intake is not purchasing high-fat and calorie-dense food. Substituting low-calorie and low-fat foods for high-calorie and high-fat foods also can substantially affect weight loss. For example, substituting a cup (8 fl oz, or 237 ml) of 1% milk for a cup of whole milk decreases caloric intake by approximately 50 kcal. If a person drinks 2 cups of milk per day, this substitution will reduce caloric intake by 36,500 kcal in 1 yr!
Meal planning is also essential. In busy households, planning healthy meals often becomes a low priority, and this can lead to meals that are easy to prepare but do not promote health or weight control. One technique for overcoming time constraints is buying breakfast foods that are quick to prepare yet are nutritious and relatively low in calories (e.g., fresh fruit, low-fat yogurt, whole-grain cereals). These foods provide a morning meal that offsets hunger and includes important nutrients.
Because many Americans are not at home for the noon meal, they often eat at restaurants that are convenient, affordable, and quick, including fast-food restaurants. Although several fast-food chains have added healthier items to their menus, the majority of fast food is high in both fat and calories. Individuals who choose to eat fast food are less successful at maintaining weight loss compared with those who avoid these food choices (19). Planning ahead might allow some people to carry their lunch to work and ensure that they can choose from a variety of healthy foods for this important meal.
The evening meal contributes a significant percentage of the daily caloric intake of many Americans. It is not uncommon for people who have limited their food intake during the day to overindulge at night. Because of the effort required to cook a meal, many people eat at restaurants or purchase packaged meals that tend to be high in fat and calories. The effort necessary for cooking nutritious meals can be reduced by doing the following:
- Cook and store meals ahead of time.
- Find a variety of low-calorie meals that are quick and easy to prepare.
- Purchase food ahead of time to avoid unnecessary shopping.
- Keep a variety of fresh vegetables on hand.
It is also important to consider the foods available for snacks. Although avoiding food between meals may be ideal for some, there are times when snacks are necessary. Foods that are nutritious and also low in calories are the best choices (e.g., fresh fruit, raw vegetables, low-fat yogurt).
Establishing a Support System
Studies have shown the benefit of having a support system when trying to lose weight (31). The source of the support, however, will vary depending on the client. A support system may be a friend, significant other, parent, coworker, therapist, or support group. Fitness professionals should encourage clients in a weight-loss or maintenance program to seek out other people to encourage them in their efforts. For some people, the reasons for overeating are emotional and deeply rooted. In these cases, a trained therapist may be needed.
A lot of people are encouraged by supporting others who also are attempting to lose weight. Many commercial weight-loss centers provide support groups, which serve several functions: They provide a group to whom participants are accountable, a setting in which helpful hints and success stories can be shared, and a nonthreatening environment where all of the participants are pursuing the same objective. In addition, Internet support groups are gaining popularity. Some of these services are free and others charge a membership fee. Consumers should seek out Internet services that meet their needs.
Committing to Behavioral and Outcome-Oriented Goals
Clients must develop goals that encourage healthy eating. Goal setting is important to help individuals remain focused on weight loss or weight maintenance. It should be a mutual exchange between the fitness professional and the client. The fitness professional provides information about healthy weight-loss or management practices, and the client identifies the behavioral goals to which she is willing to commit.
Typically, weight loss is outcome oriented (i.e., the end result is the measure of success). Weight-loss goals should be reasonable for the client and should follow the guidelines listed previously in this chapter. In contrast to outcome goals, behavioral goals focus on the process of weight loss, not the final outcome. Behavioral goals can help the client make behavior and lifestyle changes that will affect weight loss or maintenance. These goals may target altering eating patterns, making wise food choices, and increasing daily energy expenditure. An example of a behavioral goal is, “I will walk the stairs to my office daily rather than riding the elevator.” More specific information on goal setting can be found in chapter 23.