DIETARY TREATMENT OF OBESITY



DIETARY TREATMENT OF OBESITY

Chapter 18 - Johanna T Dwyer, DSc, RD and Kathleen J Melanson, PhD,RD,LD

September 24, 2002

INTRODUCTION

There is a great deal of misinformation about weight control in this country today. Self-initiated approaches to weight reduction are often not effective . People often believe that there is a quick and easy remedy for curing obesity. In fact there is no easy way. The only way to keep off excess weight is through lifelong behaviors involving physical activity, balanced with a healthy diet. [1]However, health professionals can help people be more effective at doing this.

Obesity is gradually gaining recognition as a chronic medical condition requiring long-term or life-long therapy to achieve improved health outcomes [1, 2]. Health professionals often ignore obesity because they regard it as being unlikely to improve with therapy. However, recent data indicate that that modest (5-10%) weight reduction in obese persons are attainable and result in clinical improvements of several health-related parameters, even if the individual remains clinically obese [3-5]. These results should be encouraging to health professionals and patients, since now they need not be overwhelmed by the inability to meet excessively ambitious or unrealistic weight loss goals [3].

Weight management counseling of overweight and obese patients deserves reconsideration because it carries a great potential for health benefits. Obese patients receiving weight reduction advice from their physicians are significantly more likely to embark on weight loss attempts than those who do not, and yet in recent surveys only 42% of obese individuals reported that they received weight loss recommendations from their physicians[6] This finding underscores the need for increased physician and health professional involvement in obesity treatment [2, 7]. When physicians are appropriately trained and include recommendations for lifestyle changes when counseling their obese patients, results are promising [8, 9]. This chapter briefly reviews steps health professionals can take to help their patients manage their weight more effectively.

RATIONALE FOR DIETARY TREATMENT OF OBESITY

The growing propensity to overweight in the United States indicates that attention to weight control and maintenance are not matters that should be confined to those who are already overweight. Weight control has health advantages, and therefore maintaining or achieving a healthy weight is important for all Americans. In weight control, an ounce of prevention is worth a pound of cure. Once weight has surpassed healthy levels it is difficult to reduce it. Therefore it is important for health professionals to monitor the weights of all their patients and to provide anticipatory guidance so that those who are already at healthy weights remain so. The Dietary Guidelines for Americans stress aiming for a healthy weight and physically active life as the foundation of a healthy lifestyle [10].One simple tool for doing so is by keeping a record of body mass index (BMI). Increases of more than a BMI unit signal the need for instituting preventive measures.

Assess Body Fat Burden and Health Status

Before any patient is placed on a reducing diet, medical assessment of his weight, fat distribution and health risks is essential.

Measure Body Mass Index as an indirect measure of body fat burden

Weight should be measured without clothing on an electronic scales, which provides accurate weights even for heavy patients. Height is best measured with a wall-mounted stadiometer. Body fat is difficult to measure directly in office practice, so the body mass index (BMI), which provides a better measure of fatness than weight alone, is calculated. The following formula is used:

      BMI= (wt, pounds x 703)/height, inches squared

Table 1 presents classifications of BMI scores for adults. The higher the BMI, the higher the health risk. Individuals over BMI 25 are considered overweight, those over BMI 30 are classified as class 1 obesity, those over BMI 35 as class 2 obesity, and those over BMI 50 as extreme obesity.

|Table 1. Classification of Weight Status by Body Mass Index (BMI) |

|Classification  |BMI (Kg/m2) |

|Underweight  |40 |

Measure waist circumference to quantify risks related to body fat distribution

The distribution of fat on the body as well as its sheer amount also alters risk. Excess abdominal fat in the viscera, characterized by an accumulation of fat centrally (sometimes referred to as android "apple" or abdominal fat distribution) is associated with greater risk than a peripheral fat deposition pattern (gynoid "pear" or lower body fat pattern). Abdominal visceral fatness is difficult to measure directly in office practice, but the waist circumference, taken at the level of the umbilicus with a plastic measuring tape, is a reasonable proxy for assessing it. The cut points for increased risk are a waist circumference of greater than 35 inches in women or greater than 40 inches in men. Table 2 shows how risks of weight related conditions such as type 2 diabetes, hypertension, and cardiovascular disease increase with greater BMI and waist circumference. Patients at high risk need increased treatment and monitoring of blood pressure, blood cholesterol and other cardiovascular risk factors. Two other factors that increase risk still further are physical inactivity, which exacerbates the severity of the other risk factors that are present as well as possibly increasing risks itself, and elevated serum triglycerides, which are another marker for increased cardiovascular risk. Although weight loss can help to lower elevated blood pressure, blood glucose, total and LDL cholesterol and triglyceride levels, and raises low HDL levels in those with abnormal values, additional pharmacologic therapy may also be necessary.

|Table 2. Classification of Risk of Type 2 Diabetes, Hypertension and Cardiovascular Disease Associated with |

|Weight |

|Classification of Fatness Status by |Increase in Disease Risk for Type 2 Diabetes, Hypertension and |

|BMI and Waist Circumference |Cardiovascular Disease Over Normal Weight and Waist Circumference |

| |Waist circumference |Waist circumference |

| |Women 35 inches |

| |Men < 40 inches |Men > 40 inches |

|Underweight (BMI 40) |Extremely high  |Extremely high |

Document other risk factors and comorbidities that increase risk and have other implications for therapy

The presence of other risk factors or clinically evident diseases further increases the health risk of obesity. Table 3 lists the major signs, symptoms and conditions that must be considered. These conditions further add to the adverse health effects of the obesity and also are problems that must be managed themselves in addition to weight control.

|Table 3. Risk Factors and Comorbidities that Increase the Risks of Overweight |

|Level of Risk  |Conditions |

|High Absolute Risk  |Established coronary heart disease or other |

| |atherosclerotic disease |

|   |Type 2 diabetes |

|   |Sleep Apnea |

|High absolute Risk if 3 or More of These Risk Factors |Hypertension |

|are Present  | |

|   |Cigarette smoking |

|   |High low-density lipoprotein cholesterol |

|   |Low high density lipoprotein cholesterol |

|   |Impaired fasting glucose |

|   |Family history of early cardiovascular disease |

|   |Age: >45 in men or >55 in women |

|Increased Risk  |Osteoarthritis |

|   |Gallstones |

|   |Stress incontinence |

|   |Gynecologic problems such as amenorrhea and menorrhagia |

Determine if the patient is a candidate for weight loss

All individuals with a BMI over 25 and those at lower BMI's with high waist circumferences and two or more of the risk factors listed in Table 3 are potential candidates for weight reduction. The goal is reduction and maintenance of a lower body weight over the long term. It this is impossible at least prevention of further weight gain should be attempted.

Assess the patient's readiness and willingness to lose weight

Unfortunately those who are most concerned about their weights are not necessarily those who are at the highest health risk. The procedures described above provide a reasonable assessment of the health risks associated with obesity and the potential health benefits accruing from weight loss. Now these risks need to be communicated to the patient. Those who are at high health risk are often unaware of how serious their problems are.

Once this has been done, a plan for dealing with the condition needs to be jointly devised with the patient. Weight control requires behavioral change and requires patient consent and "buy-in". Therefore patient readiness needs to be ascertained. Some patients are ready to start a treatment program immediately. Others are unable or unwilling to embark on a weight reduction program, but they are willing to take steps to avoid further weight gain or perhaps to work on other risk factors such as cigarette smoking, and they should be encouraged to do so. For those not ready to act, the issue should be deferred and brought up at the next visit.

Other normal weight patients who wish to control their weight may also ask for help. They can be counseled to avoid weight gain and provided with helpful information on healthy eating and physical activity levels, which is summarized at the end of the chapter.

Decide if Dietary Treatment is the Appropriate Option

Weight reduction with dietary treatment is in order for virtually all patients with a BMI 25-30 who have comorbidities and for all patients over BMI 30.

Prescription drugs may also be considered for those with a BMI of 27-30 if comorbidities are present, and for heavier patients even in their absence if they are unable to lose weight with dietary measures alone. Only two prescription drugs are currently approved for long-term use in weight reduction. Sibutramine (Meridia) is an appetite suppressant that works centrally to decrease appetite. Its advantages include slightly greater net weight losses and longer maintenance of losses than diet and physical activity alone. Disadvantages include variable increases in blood pressure and cost. Orlistat (Xenical) is a drug that operates at the level of the gut to inhibit pancreatic lipase and fat absorption. It also increases net weight losses, at least over the short run compared to diet alone. It also may foster adherence to low-fat reducing diets because of the fat malabsorption it induces. Its disadvantages are malabsorption sometimes, accompanied by anal leaks, and decreased absorption of fat-soluble vitamins. Dietetic counseling is helpful in managing the drug's effects. The drugs are costly. Patients who are likely to respond to drugs do so within the first month of therapy and if they fail to lose about 5lb in the first month, the drug is unlikely to be effective.

Surgical options such as gastric bypass and gastroplasty are recommended only for patients with BMI 35 with comorbidities and are beyond the scope of this chapter.

Clarify Reasonable Goals and Define Successful Outcomes for Weight Reduction, Set a "Healthier weight" target for the patient

The approach to setting goals and treating [11] obese patients must be non-judgmental and focused on an acceptable weight for good health outcomes rather than solely on body weight [12]. Everyone wants to be healthy. By concentrating on improving health and risk factors, rather than simply on loss of weight, excessive focus on the aesthetic and cosmetic aspects of weight can be avoided[13].

Begin therapy by working with the patient to set a healthier weight. From the medical perspective, the goal is to maximize health related effects while minimizing insults to the patient's quality of life. The physician is uniquely qualified to define and communicate what a "healthier " weight is to the patient since weight reduction targets vary depending on the patient's weight and comorbidities. Progress toward healthier weight goals should involve a gradualist approach that minimizes health risks that is timed to patient readiness and motivations and that provides reachable short-term targets.

A reasonable target: 10% of body weight over about 6 months

The target is usually to achieve a loss of about 10 percent of body weight over a period of six months, and to keep weight at this lower level thereafter. It is moderate enough to be achievable and reduces fat and weight enough to decrease obesity-related risk factors. After about 6 months most patients have difficulty-sustaining adherence, and weight plateaus as resting metabolic rate and energy output decrease.

This target can be achieved with a caloric deficit of 500-1000 Calories a day or 1-2lb a week. A weight reduction plan of about 1000-1200 Calories for women or 1200-1600 Calories for men along with increased physical activity and behavioral modification will usually produce this. With a caloric deficit of 500-1000 Calories a day after 6 months with perfect adherence losses would theoretically be between 26 and 52 pounds, but in actuality losses are usually about 20-25 pounds, since adherence is never perfect. A BMI unit is approximately 10-15 pounds depending on height and weight and a decrease in 2 BMI units over 6 months is another way of starting the goal. Reductions of this magnitude decrease risk factors and thus result in "healthier" weights. If further weight reduction is necessary after 10% of body weight is lost, it can be attempted after weight has been maintained for several months at a healthier level.

Adopt realistic goals that include health objectives

Many overweight patients have already tried in the past to lose on their own. For example, in the United States nearly half of women, and more than a third of men report that they are attempting to lose weight [11]. However, with self-directed efforts, their reasons are often aesthetic or social rather than health-related, the goals they adopt are often unrealistically ambitious, the information they obtain on weight management is often inaccurate, and the support their receive is frequently inadequate. Solo efforts may fail and lead to discouragement and a sense of futility[14]. The vital role of the physician is to provide the motivation, information, counseling and support patients need to be more successful.

Patient weight goals are often very different from those of their healthcare providers. In general, patient's ideal for weight reduction are two or three times the 8-15% losses that motivated patients usually achieve [15]. Patient weight goals depend on their motivation, the salience of weight as an issue to them, their perception of health risk, and other priorities in their lives. Some patients simply are not motivated to lose weight, or are motivated but are not willing to do so at present. It makes no sense to give an unmotivated patient a goal he cannot achieve. It is far better to come to agreement about the steps he/she is willing to take now to begin to deal with their health problems. For patients who are already highly motivated or become so when they are told about the related health risks, the physician's job is easier. These patients' weight targets are often unrealistically low (e.g. targets of 30% or more of body weight) and their time frames for achieving losses unrealistically short (e.g. weeks rather than months). For them, advice and counseling on more realistic targets and time frames is helpful.

Patients are often unreasonably hard on themselves and believe that if they are to undertake weight reduction, drastic measures are called for. A healthy weight goal consisting of an initial loss of 1-2 BMI units is often much less extreme than the weight loss patients think of as ideal, but it is much more likely to be achievable. A loss of 10% of body weight, if sustained, significantly reduce risks for coronary heart disease and other comorbidities. The physician plays an important role by giving patients permission to adopt more realistic and achievable targets.

Define Success in Broader Terms than Weight Loss Alone

Definitions of the success are patient-specific. The reduction of risk factors, even if weight is not lost, is "success" from the health standpoint. For some patients, prevention of further weight gain after years of slow, steady increase is progress. The maintenance of a reduced weight, even if it is still within the range of clinically defined obesity is also "success" since it reduces health risks. Thus the definition of successful obesity treatment must be broadened to encompass goals other than weight loss, and these broader goals need to be communicated to patients. For example, outcomes to target may include improved metabolic profiles, reduced blood pressure, fasting blood lipids or glucose, increased daily physical activity and fitness, greater consumption of fruits, vegetables and fiber, reduction in dietary fat, changes in specific unhealthful habits as well as enhanced self-esteem, self-efficacy, quality of life and functional capacity [1, 16].

Individualize the Diet and Treatment Program

Evidence-based reviews of successful weight control techniques increasingly emphasize the importance of individualized, multidisciplinary care, a health-outcomes focus, realistic goal setting and making permanent lifestyle change[5]. The specific underlying factors that induce a chronically positive energy balance and thus the development of obesity differ among individuals. Furthermore, daily lifestyle, environment, resources and social situations may vary considerably. Thus, it is appropriate to individualize the weight reduction strategy in order to promote adherence , and thus success [16]. Different specific dietary approaches for maximizing adherence are successful to varying degrees in different individuals. No single approach is appropriate for everyone, and so those who are embarking on diets should discuss the approach that best suits their needs with their physician and/or dietitian. In addition to energy content, individual food selections and meal frequency, other factors that may make a diet suit the individual. These include cost, convenience, treatment of co-existing health conditions, strategies for adapting the reducing diet to different social situations and a continued plan for healthful life-long weight maintenance [17]. Throughout the weight loss and management program, it is vital that the patient be counseled on making proper dietary choices, thus allowing for independence and self-efficacy in forming daily eating patterns. Representative dietary education topics are listed in Table 4 The National Institutes of Health, the American Dietetic Association and other organizations provide materials, checklists, guidelines, menus and recipes to assist in such patient education [5, 16]. Patients should be encouraged to maintain daily records of food and beverage intake, since this often increases awareness of consumption, and promotes dietary adherence.

|Table 4. Nutrition Education Topics for Weight Management |

|Energy values of different foods |

|Food composition (fats, CHO, fiber, protein) |

|Reading nutrition labels |

|The Dietary Guidelines for Americans |

|Standard portion sizes compared to portions usually eaten |

|Usual portions and calories in commonly consumed fast foods |

|New habits of food purchasing |

|Food preparation for healthier intake |

|Avoiding overconsumption of foods with high energy content and density |

|Adequate water intake |

|Portion size reduction |

|Limiting alcohol consumption |

|Eating strategies for restaurants and social situations |

|Awareness of physiological hunger and satiety cues |

|Awareness of physical activity levels (use of pedometer and activity diaries may help) |

|Adapted from NIH Obesity Guidelines 1998 |

PLAN THE ENERGY DEFICIT PHASE OF WEIGHT CONTROL 

GENERAL PRINCIPLES

For the individual who is already overweight, successful weight control requires a phase in which dietary energy intake is reduced while energy output is increased or at least not decreased. This phase is referred to as the energy deficit phase. The essential components of weight reduction are decreased energy intake, increased energy output through physical activity, behavioral modification of lifestyles, and alterations in the larger environment that foster these measures. Although this chapter focuses on dietary measures in the treatment of obesity, all reasonable treatment programs for overweight should include the full complement of these measures.

CALORIC DEFICIT NEEDED TO LOSE WEIGHT

Obesity results from the accumulation of excessive body fat as adipose tissue. Numerous experimental studies under controlled conditions have established that it takes approximately 3500 Calories for an overweight person to lose a pound of fat. Although compensatory changes in resting metabolism, the energy cost of work, and discretionary physical activity may occur that sometimes alter this figure by 100-200 Calories, over the long term this relationship holds quite well. Thus the size of the energy deficit between actual energy needs and the energy output determines the slope of decline in fatness over time.

GOAL OF ENERGY DEFICIT PHASE

The goal of the dietary treatment of obesity in the energy deficit phase is to decrease body fat stores without unduly depleting the lean body cell mass that includes skeletal muscle and the vital organs. During weight loss some lean tissue is always lost along with the fat. While weight is being lost, stores of other nutrients such as vitamins, minerals and electrolytes must be maintained. Fortunately, dietary and other strategies are available to minimize loss of lean tissue and other nutrients, and these must be incorporated into sound dietary treatment plans.

TROUBLESHOOTING WHEN DIETS DON'T SEEM TO WORK

Some of the money factors that contribute to patients losing less weight than they expect to while on reducing regimes are described below.

1. Food intake varies greatly from day to day. People vary in their eating patterns from day to day. Weight reduction prescriptions are sometimes made by suggesting a caloric deficit of approximately 500 Calories per day to achieve a weight loss of about a pound a week. This is an abstract goal that is difficult to remember. However, since most people vary greatly in their food intake from day to day, they have great difficulty recognizing whether in fact they are eating less than before. For this reason simply urging people to "eat less" of certain foods is unlikely to help.

2. Self -reports of energy intake are underestimated.

The average healthy adult American male consumes approximately 2800 Calories per day, and the average female about 1800 Calories, yet such intakes are seldom actually reported. The reporting of energy intakes is difficult even for individuals who have been trained to report accurately. Many days of observation are necessary since energy balance is only achieved over weeks, not days. Thus a report from any given day is certain to contain considerable random error if it is used to estimate usual caloric intake. However, more serious errors also are present. Underreporting of energy intakes is common and large (e.g. 20%) in virtually all people, and it is particularly common among the overweight. Recent studies with objective biomarkers of energy output such as doubly labeled water indicate that underreports may be as great as 1200 Calories per day in obese persons [18]. Indeed, subjective reports of energy intake are often so low that those who report them should be losing weight when in fact they are gaining. This is biologically implausible.

A more common problem is that weight loss is less, not more than expected. This too is a result of underreporting. When overweight people report their intakes by recall they often underestimate their intakes by 30-40%. They are likely to make similar mistakes in underestimating their intakes on reducing diets because of difficulties in portion size judgment, forgetting, the social desirability of reporting adherence to the prescribed regime, and other factors. Thus on a 1200 Calorie diet actual consumption may approximate 1600 Calories . Methods for assisting dieters to decrease these errors include the use of household measures or weighing scales to determine amounts eaten more precisely, the use of food diaries to help in self-monitoring of food intake and making them more conscious of what they are eating, the use of portion-controlled liquid meal replacements, frozen low calorie entrees, and other foods which are fixed in their portion sizes.

Underreporting is especially pronounced in the severely obese, women, smokers, those of low educational and socioeconomic status [19]. Those who are under-reporters tend to be so consistently [18, 20]. Thus consistency in reporting does not necessarily mean that the report is accurate. In spite of these limitations, self-reports are useful to the patient and counselor for obtaining clues on dietary patterns and portion sizes that may be helpful in counseling the patient. However it is important to recognize their limitations

3. Self -reports of energy output are also underestimated. Self-reports of energy output as measured by physical activity questionnaires have also been validated using doubly labeled water methods. Lengthy questionnaires used for research purposes are quite good[21] However, the variability of most questionnaires of the type that are used clinically is high, and they are not accurate for individuals [22] . However, as is the case with dietary reports, they are still useful for self-monitoring but are inaccurate for prescribing or assessing energy intakes or outputs. Uniaxial accelerometers such as the Caltrac that measure the degree and intensity of movement in a vertical plane, or triaxial monitors like the Tracmore are more accurate and are now often used as self-monitoring tools[23]. These are very helpful to some patients.

4. Compensatory decreases in energy output occur on most reducing diets, particularly if they are very restrictive in energy.

As a rule of thumb, for every 500 Calorie deficit, compensatory decreases in energy output due to decreased resting metabolic rate, discretionary physical activity and the energy cost of work involving moving the body are approximately 165 Calories, leaving only 335 Calories that actually contribute to weight loss. Thus the caloric deficit again may prove to be less than anticipated and predicted weight loss is less than expected [24] Some data suggest that energy balance is more strongly defended during energy deprivation than it is during energy surplus, impeding weight loss to a greater extent than weight gain [25-27]. In part, these retarding effects weight loss may be due to alterations in resting metabolism and non-obligatory physical activity..

5. Shifts in water balance obscure true decreases in body fat and overestimate fat-related weight loss. Dramatic alterations in weight often occur on reducing diets, particularly in the first few weeks on a severely hypocaloric regime with deficits of 1000 Calories per day, and on ketogenic diets [28]. These fluid shifts are larger on some reducing diets than others, depending on their caloric level and macronutrient composition. They are also more apparent on hypocaloric regimes that are very low in carbohydrate ( ................
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