Weight and Body Composition Management

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Donald Rodd, PhD, EPC  
  
Obesity is a complex chronic condition that develops from multiple interactions between genetics and environment characterized by excess body fat.  This excess adiposity or obesity poses a serious and growing public health problem.  Obesity is associated with increased mortality and is a risk factor for several chronic diseases including hypertension, dyslipidemia, diabetes, cardiovascular disease, sleep apnea, osteoarthritis and some cancers [1].  Despite the public health concern the incidence of obesity in the United States is increasing.

DEFINING OVERWEIGHT AND OBESITY

Obesity results when the body stores surplus energy in adipose tissue as fat. Surplus energy results when a mismatch in the energy balance equation (Energy balance = Energy in – Energy out) exists.  This mismatch can be the result of increase energy intake or decreased energy expenditure or both.  The point at which accrued fat constitutes obesity is equivocal, however guidelines have been established to determine when an individual is considered obese.
Obesity can be measured directly using various methods of body composition analysis or defined using the body mass index (BMI) (weight in kg/height in m[size=-2]2) which is an indirect measure of body fat (Figure 1)(Table 1).  According to the World Health Organization overweight is defined as a BMI of 25.0-29.9 and obesity as a BMI equal to or greater than 30 [2].  The BMI is widely used in large population studies and is a useful marker of disease status at low cost.  While the BMI has a good correlation (r = 0.70) with body fat measured directly [3], it is somewhat insensitive in detecting obesity or leanness in individuals with extremes of fat free mass and it does not adequately characterize the distribution of body fat.  
There is a remarkable amount of heterogeneity in obese individuals.  Some obese individuals exhibit normal metabolic risk factors despite the presence of substantial excess body fat while others who may be moderately obese may express metabolic disease or diseases such as type II diabetes, atherosclerosis and cardiovascular disease.  Therefore, the notion of fat distribution or fat patterning has been emphasized.  Distribution of fat is important since certain fat patterns have a higher morbidity risk.  Excessive intra-abdominal fat or upper body fat or android-type fat patterning (because it occurs more often in males) or apple shape is associated with increased morbidity and is an independent predictor of health risk [4] than gluteofemoral fat patterning or gynoid fat patterning or pear shape.  The apple shape adiposity can occur in both genders and is associated with many of the health problems listed for obesity including hypertension, hyperlipidemia, cardiovascular disease and diabetes.  Fat cells in the abdominal area appear to be more active, taking up and releasing fat, than fat cells in the gluteofemoral area.  Since it is intra-abdominal fat that is more strongly associated with negative health consequences, the ratio of waist to hip circumference (WHR) has been used to determine the type of obesity present. Risk for disease increases when the WHR > 0.9 for men and > 0.8 for women.  In addition, the waist circumference alone is used as a measure of abdominal adiposity and an increased risk for health is present when waist circumference exceeds 102 cm (40 inches) for men and 88 cm (35 inches) for women  (Figure 2) (Table 1) [5].

DEVELOPMENT OF OBESITY

Weight mismanagement and obesity usually develop from long-term energy imbalances due to lack of adequate physical activity, excessive caloric intake or both and the influence of heredity.  Genetic factors may explain why some individuals are more prone to obesity [6,7]. Individuals with inherited tendencies must be more careful with their dietary and exercise habits to counteract genetic factors and they may need to accept a body shape that has not been deemed as ideal.  In other words, the genes possessed by an individual can predispose one to obesity and the appropriate environment induces the expression leading to obesity [8]. While genetics can be a powerful influence on body composition, it does not mean an individual is destined to become obese.  Lifestyle behaviors including what and how much is consumed and level of physical activity can also impact and influence overweight and obesity. If energy consumption is greater than energy expenditure a positive energy balance results and fat is stored.  For every 3,500 calories of excess energy accumulated, one pound (0.45 kg) of fat is stored.  While the type of calories consumed has become controversial, the recommendation for energy restriction is still used to create a mismatch in the energy balance equation.  A negative energy balance occurs when the energy expenditure exceeds energy input.  This can be accomplished by reducing food intake or increasing physical activity level. A caloric deficit of 3,500 calories produces a loss of one pound of fat.
  
WEIGHT LOSS AND WEIGHT MANAGEMENT STRATEGIES
Dietary and Lifestyle Modifications

According to the American Dietetic Association, individuals should decrease consumption of foods that are high in fat, calories, salt and simple sugars and increase consumption of foods that are nutrient dense but not calorie dense and allow their hunger and satiety to guide them in choosing food quantities [9].  This approach involves a change in eating attitudes and behaviors and develops into a long-term strategy that leads to slow and continued weight loss that can be sustained.  This approach allows the body’s internal regulation to guide the individual to consume nutrient dense foods that results in balance, moderation and reduced feelings of deprivation [9].  To achieve success with this strategy may require intervention to teach the individual to correctly perceive the signals of hunger and satiety and allow the signals to guide them to proper food intake.
Many individuals may have a problem with the previous strategy and may require more guidelines to enlist their dietary modifications.  With the use of diets individuals are instructed to modify their intake to achieve a moderate decrease in caloric intake to achieve a slow and progressive weight loss.  The low calorie diet (LCD) (800 to 1,500 calories) tries to induce a caloric deficit of 500 to 1,000 calories per day with a result of one to two pounds (490 to 980 grams) of weight lost per week.  The LCD modifies the composition of the diet and emphasizes portion control to reduce energy intake.  In reduced calorie diets it is important that total calories are reduced otherwise little weight will be lost.  LCDs reduce body weight by an average of 8% over a 6-month period and produce significant reductions in waist circumference.  The weight loss consists of about 75% fat and 25% lean tissue [11].
Starvation diets (0-200 calories per day) and very-low calorie diets (VLCD) (200-800 calories per day) should be avoided.  Starvation diets result in loss of lean body mass and loss of minerals from diuresis.  VLCDs are protein sparing modified fasts and typically use a premixed liquid, meat, fish or poultry.  When employed, VLCDs are typically used in a controlled setting by a physician or health professional for individuals with a BMI >30 and have failed in other approaches.  Patients on a VLCD should be under medical supervision and should receive supplemental vi*****ins and minerals [10].  Clinical trials have shown that LCDs are just as effective as VLCDs in producing weight loss after one year [12].  Although more initial weight may be lost using VLCDs, more weight is typically regained.

PHYSICAL ACTIVITY

Although physical activity is typically integrated into a strategy for weight management, the actual contribution of physical activity toward the mechanism of weight loss is poorly understood.  It is widely believed that physical activity is an important factor in the etiology of obesity and that lack of energy expenditure is a main contributor to the epidemic of obesity in society [16-19].  Therefore, physical activity is used to increase the energy out side of the energy balance equation.  However, although data indicates that physical activity and the prevalence of obesity are inversely related [14,15], it is not certain whether inactivity causes obesity or if obesity leads to inactivity.  Thus, the role of physical activity will be explored in more detail.
Many individuals on a weight loss program begin aerobic physical activity to accelerate their loss of body weight.  However, it has been demonstrated that exercise alone without any caloric restriction results in very little if any significant change in body weight [20-24].  In addition, when physical activity in the form of aerobic exercise is included in a weight loss program using caloric restriction of some kind, little if any additional weight is lost due to exercise [24-28].  Therefore, data from the literature demonstrate that moderate amounts of aerobic physical activity, when combined with a diet that reduces calories, contributes little if any additional weight loss.  Aerobic physical activity must be of long duration (greater than one hour) and high in intensity to be an effective intervention for weight loss, conditions that typically cannot be met by obese exercisers [29-30].  However, exercise should be included in a weight loss program to increase the amount of physical activity and to improve cardiovascular fitness.
The relationship between physical activity, dieting and resting metabolic rate (RMR) is unclear. Since RMR accounts for a large proportion of total energy expenditure, (it can make up 60 to 70% of a sedentary individual’s total energy expenditure) it is important to know the effect of diet and exercise on RMR.  Dieting produces a reduction in RMR, at least in the short-term during the calorie restriction.  However, it is not clear if the decrease in RMR is proportional to the decrease in body size or to the energy deficit.  In addition, it is not clear whether exercise can prevent the reduction in RMR.
Decreases in RMR up to 30% have been reported following weight loss particularly using VLCDs and long term fasting [31-34].  Some studies have demonstrated low levels of thyroid hormone and urinary norepinephrine during caloric restriction [35-37] which may, in part, be responsible for the decreased RMR.  Can exercise prevent the diet induced decrease in RMR?  Most studies indicate that exercise has little or no effect on the diet-induced decrease in RMR [38-44].  The decrease in RMR is thought to be from loss of fat-free mass since there is a close association between the two.  Loss of fat-free mass during caloric restriction ranges from 50% during fasting [45], about 25% during VLCDs with protein supplementation [46] and 10% with a 1,200-1,500 Calorie diet [47].  While some studies have indicated an increased or maintained RMR with diet and resistance training [48-50], thought to be from maintaining fat-free mass during the weight loss, other studies indicate that resistance programs, even intense resistance training programs had little effect on fat-free mass during caloric restriction [51-54].

Drug or Pharmacotherapy

The National Heart Lung and Blood Institute (NHLBI) promotes the use of FDA approved drugs for weight loss as an adjunct treatment for obesity in some individuals and should be used only with a program that includes dietary interventions, physical activity changes, and behavior therapy [55].  If lifestyle changes do not promote weight loss after 6 months, drugs should be considered.  Pharmacotherapy is limited to those patients who have a BMI equal to or greater than 30, or those who have a BMI equal to or greater than 27 with obesity-related risk factors or diseases present.
Diet drugs have been available for some time; in the 1950s and 60s amphe*****ine derivatives (speed) were widely used.  However, prescribing amphe*****ines for weight loss fell out of favor due to addictive properties of the drugs and from the 1970s to the 1990s pharmacologic intervention for obesity decreased.  The 1990s saw an increase in the use of prescription drugs for the treatment of obesity.  In the 1970s the FDA approved a drug called fenfluramine and then in 1996 approved a more potent form of fenfluramine called dexfenfluramine. I n the 1990s a combination of a drug called phentermine and fenfluramine or fen-phen was prescribed for weight loss.  Phentermine was also used in combination with dexfenfluramine also called dex-fen-phen.  The drugs worked by increasing Serotonin levels in the brain and people did lose weight with these drug combinations.  However, in 1997 reports of heart valve disease were linked to the use of fenfluramine and dexfenfluramine and these drugs were withdrawn from the market.
In 1997 the FDA approved sibutramine for weight loss.  Sibutramine is an appetite suppressant that enhances norepinephrine and serotonin activity in the brain by inhibiting uptake not by stimulating release [56,57].  In 1999 the drug Orlistat was approved by the FDA as in obesity treatment. Orlistat reduces the fat absorption of the small intestine by about one third [58].
Increasing thermogenesis is a strategy employed in weight loss and many over-the-counter weight loss supplements use this strategy.  Many weight loss supplements include caffeine, ephedrine and/or ephedra as ingredients. Caffeine, a natural occurring alkaloid present in more than 60 plant species, has a stimulatory effect on metabolic processes including increased central nervous system effects, heart rate and blood pressure [59].  Ephedra is a plant that contains ephedrine as the principal active alkaloid.  Synthetic ephedrine is regulated as a drug and is found in many over-the-counter and prescription drugs.  Ephedra/Ephedrine increases metabolic rate by stimulating beta-adrenergic receptors and enhances weight loss in a dose dependent manner [60].  Ephedrine/Ephedra acts primarily through release of stored catecholamines with some direct action on receptors.  It is non-selective in action and mimics epinephrine in its effects as well as having access to the central nervous system.  Side effects include anxiety and other psychiatric symptoms, autonomic hyperactivity and heart palpitations [59].  In addition, the use of ephedrine/ephedra has been linked to death and serious injury including myocardial infarctions, cerebrovascular accidents and seizure [61].
Surgery
Gastric surgery has been shown to be an effective approach for long-term weight loss in extremely obese individuals and should be reserved for those in whom other methods of weight loss have failed.  Surgical procedures promote weight loss by restricting food intake and causing malabsorption.  Gastric banding reduces food intake by placing a band around the upper stomach which allows only a small amount of food to enter the stomach [62].  Vertical banded gastroplasty use staples placed vertically in the upper part of the stomach and a band to create a small pouch which limits the passage of food into the rest of the stomach.  Gastric bypass surgeries create a small pouch by stapling or removing portions of the stomach and bypassing the duodenum and other segments of the small intestine producing malabsorption [62].
Relapse Prevention
Preventing the regain of fat is the major challenge of a weight maintenance program. Unfortunately, many regain their fat within three to five years [63].  To help maintain weight loss, the NIH recommends that maintenance efforts continue indefinitely.  At a minimum, all who have lost weight should participate in a six to twelve month maintenance program and be prepared to reenter a weight loss program when a gain of ten pounds is detected. Maintenance programs should focus on modifying the individual’s lifestyle including diet, physical activity habits and behavior modification [64,65].  Dietary and physical activity modifications need to be integrated as a permanent lifestyle change.  In addition, support is needed from all aspects of life (family, friends, etc) to ensure success of long-term weight management.
Conclusion
Achieving healthy body weight and composition are important to maintain overall health and to decrease the risk of morbidity and mortality.  Practicing behaviors associated with a healthy lifestyle can help achieve weight management for many.  However, for some individuals weight management is difficult and they may require drastic interventions to decrease accumulation of excessive body fat.  Weight management can be an achievable goal for all with patience, setting realistic goals and time without relapse.

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Table 1 - Body mass index (kg/m[size=-1]2) and Waist Circumference Associated with Disease Risk

BMI = Weight in kg / Height in M[size=-1]2
BMI = weight in pounds / height in inches / height in inches / 0.0014192

[size=-1]Classification	[size=-1]BMI	[size=-1]Obesity Class	[size=-1]Disease Risk by Waist Circumference	[size=-1]Disease Risk by Waist Circumference
			[size=-1]Males (equal to or less than 102 cm) [size=-1]Females (equal to or less than 102 com)	[size=-1]Males > 102 cm [size=-1]Females > 88 cm
[size=-1]Underweight	[size=-1]<18.5
[size=-1]Normal	[size=-1]18.5-24.9
[size=-1]Overweight	[size=-1]25.0-29.9		[size=-1]Increased	[size=-1]High
[size=-1]Obesity	[size=-1]30.0-34.9	[size=-1]I	[size=-1]High	[size=-1]Very High
	[size=-1]35.0-39.9	[size=-1]II	[size=-1]Very High	[size=-1]Very High
	[size=-1]>40	[size=-1]III	[size=-1]Extremely High	[size=-1]Extremely High

From: Clinical Guidelines on the identification, evaluation and treatment of overweight and obesity in adults.  Washington, DC: National Institutes of Health, Obesity Education Initiative Task Force, 1998.

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Figure 1. A nomoram  for determining body mass index (BMI). To  use this nomogram, place a straight edge between the column for height  and column for weight connecting an individual’s numbers for those two variables. Read the BMI in kg/m[size=-2]2 where the straight line crosses the  middle lines when the height and weight are connected. From: Bray, G.A. Obesity: definition. diagnoses and disadvantages. The Medical Journal of Australia 142:S2-58; 1985.  

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Figure 2. Nomogram for determining waist to hip ratio. Place a straight edge between the column for waist circumference and the column for hip circumference and read the ratio from the point where this straight edge crosses the WHR line. The waist or abdominal circumference is the smallest circumference below the rib cage and above the umbilicus, and the hips or gluteal circumference is taken as the largest circumference at posterior extension of the buttocks. From: Bray, G.A and Gray, D.S. Obesity: Part I.  The Medical Journal of Australia 142:S2-58; 1985.

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