Weight Reduction

Obesity is based on the BMI. The BMI is calculated by dividing the weight in kilograms by the square of the height in meters (kg/m2). More than half of the adults in the United States are considered overweight, with a BMI of greater than 25; one-third of the adults in the United States are obese, with a BMI greater than 30.

Any diet can be effective if there is a deficit of caloric intake relative to caloric expenditure. In patients on diet alone, there is generally a 5-6% reduction in body weight over the first 6 months of treatment, with the weight slowly returning over 12-24 months. Compensatory changes in energy expenditure oppose maintenance of lower body weight.

The Atkin's diet recommends induction of weight loss with only 20 g of carbohydrate daily with consumption of green salads and other vegetables, plus liberal amounts of fat and protein. Carbohydrate intake gradually increases with the maintenance program.

Carbohydrate restriction leads to ketosis, with fat from adipose tissue being the major source of energy. Ketosis can suppress appetite and have a diuretic effect. The low-carbohydrate diets are usually associated with quick weight loss in the first 1-2 weeks.

A study comparing low-carbohydrate diets (<30 g/day) with a low-fat, calorie-restricted diet in 132 severely obese patients with a mean BMI of 43 and a high prevalence of diabetes and the metabolic syndrome showed that after 6 months, the 43 patients still on the low-carbohydrate diet lost a mean of 5.8 kg, compared with 1.9 kg lost by the 36 patients still on the low-fat, low-calorie diet.

At least for the first 6 months of a high-fat, low-carbohydrate diet, there seem to be no adverse effects on risk factors for atherosclerosis, although carotid intimal thickening can occur if high-saturated fat alternatives to carbohydrates are chosen. Ketosis can cause bad breath and prolonged ketosis may increase the risk of osteoporosis caused by calcium loss from bone. The long-term safety of this diet remains to be demonstrated.

The South Beach diet adds more grain and fiber to the regimen and seems to offer a more practical alternative for many individuals who have difficulty restricting carbohydrate intake.

Nonetheless, it is important to understand that with both the Atkin's and South Beach diets, significant attention has to be devoted to reduction in trans fatty acid and saturated fat content, particularly in individuals who have existing arteriosclerotic vascular disease or are prone toward arteriosclerotic deposition. This seems to be a more prudent approach until further study has been completed.

Medications currently available by prescription to aid in weight reduction are as follows (33):

1. Sympathomimetic amines. Methamphetamine (Desoxyn) and phentermine (Ionamin) are controlled substances. Phentermine was used with fenfluoramine as "Phen-Fen" until the combination was associated with heart valve abnormalities. These drugs are approved for short-term use only and are moderately effective when used in conjunction with diet. Adverse effects include dry mouth, hypertension, nervousness, insomnia, and sexual dysfunction.

2. Orlistat (Xenical). This lipase inhibitor decreases absorption of fat from the gastrointestinal tract. Adverse effects include flatulence and oily spotting with discharge and fecal urgency.

3. Cybutrimine (Meridia). This drug is a serotonin, norepinephrine, and dopamine reuptake inhibitor. This medication has been used to safely promote weight loss over a prolonged period. Side effects include hypertension, dry mouth, and insomnia. Cybutrimine should not be used with selective serotonin reuptake inhibitors (SSRIs).

4. SSRIs. Although some reports indicate that these drugs may cause weight gain, other studies show weight loss. This can be seen especially with those patients who tend to eat when depressed. Sexual dysfunction and decreased libido remain the major problems with this class.

5. Bupropion (Wellbutrin SR). This non-SSRI has been modestly effective in promoting weight loss in doses of 300-400 mg/day. This drug is generally well-tolerated but can increase the risk of seizures (this is less likely with the sustained-release preparation).

6. Zonisamide (Zonegran). This antiepileptic drug causes weight loss as a side effect. In a 16-week trial of 60 patients with a mean BMI of 36.3, average weight loss was 5.9 kg compared with 0.9 kg in the placebo group. A 16-week extension study showed a further 3.3 kg weight loss compared with 1.5 kg in the placebo group. Cognitive problems, difficulty concentrating, and rare reports of Stevens-Johnson Syndrome have been reported (34).

7. Topiramate (Topamax). This antiepileptic drug was evaluated in a double-blind trial in 385 patients on a reduced-calorie diet. Here, 64-384 mg/day of topiramate for 6 months led to a 4.8-6.3% weight loss compared with 2.6% for placebo. Paresthesias, somnolence, and difficulties with concentration and attention were reported side effects (35).

8. Metformin (Glucophage). In the Diabetes Prevention Program, patients with impaired glucose tolerance lost 2.1 kg compared with 0.1 kg with placebo. The 1994 Biguanides and the Prevention of the Risk of Obesity (BIGPRO) trial evaluated this drug in nondia-betic patients and found similar weight loss with this product in that population. This drug has not been formally approved for use in impaired glucose tolerance or for weight loss in nondiabetic patients (36).

Surgery for weight reduction includes the following (33):

1. Roux-en-Y gastric bypass. This procedure is the treatment of choice for patients more than 100 lb over desired weight or who have a BMI greater than 40. The first portion (2030 mL) of the stomach is clipped with staples and anastomosed to the jejunum, bypassing most of the stomach, the entire duodenum and the first 15-20 cm of the jejunum. With this procedure mean weight loss is 65-75% or 35% of initial weight. This procedure can reverse the glycemia of type 2 diabetes if performed early. Perioperative mortality is less than 1%, with deficiencies of calcium, iron, vitamin D, and B12 because of malabsorption. Dumping syndrome and wound infections have been reported, with life-long follow-up necessary to prevent and treat deficiencies and the complications of ulcerations at the gastroenterostomy stoma and the duodenum.

2. Vertical banded gastroplasty. Staples are used to create a 15-20 mL gastric pouch in the upper stomach, with a small calibrated opening in the rest of the stomach. Mean weight loss is as high as 60% in the initial postoperative period, although many patients can regain lost weight over 5-10 years. Complications include reflux, stenosis, and staple-line breakdown, with 15-20% of patients requiring a second procedure to correct outlet stenosis or severe reflux. There is no malabsorption with this technique and perioperative mortality is less than 1%. This procedure is the least efficacious, with only short-term weight loss of 35-50%. Reoperation rates are high as a result of reservoir breakdown or component deterioration.

3. Biliopancreatic bypass with duodenal switch. This procedure can lead to 75-80% weight loss, restricts the stomach, and causes malabsorption. The greater curvature of the stomach is resected, leaving a small gastric pouch (100-250 mL), and the proximal duodenum is anastomosed to the distal 250 cm of ileum, bypassing the duodenum, the entire jejunum, and the rest of the ileum. Perioperative mortality is 1% higher than the other procedures, and metabolic malabsorption problems of anemia, fat-soluble deficiencies, and protein-calorie malnutrition can result.

In treating the obese patient, recognition and determination of goals is critical. Commitment of the patient to a practically designed program is critical to success. Realistic goals need to be set to avoid patient frustration. Positive reinforcement behavior modification, increased physical activity, and judicious use of pharmacotherapy all play an important role.

Modification of eating and activity habits following a set of principals and techniques can be used in an efficacious way in helping patients battle with obesity. Patients should constantly be reminded of the consequences of being overweight and of dietary indiscretion, although the physician should avoid being dictatorial or dogmatic.

In their review and practical dieting outline, VanWarmer and Boucher list the five "As" for weight-management counseling. These include (37):

1. Assessing the patient by identifying any biological, genetic, or behavioral risk factors (including accurate measurements of height, weight, waist circumference, and BMI), and identifying the presence of any other behavioral mediators, such as barriers to weight loss, social support, or change of status or occupation.

2. Advising the patient, including recommending a weight-management program and reviewing the recommendations, particularly for the patient with diabetes and patients with specific dietary habits, and recommending helpful stress-management techniques. It is important for the physician to give clear respectful advice and to link these recommendations with outcome data.

3. Agreement. Setting up an agreement with the patient for both short-term goals (including calorie restriction, glucose monitoring, and exercise) and long-term goals (hemoglobin A1-C, lipid profiles, and weight reduction), and collaborating on acceptable approaches to changing the patient's lifestyle and stressing achievable goals.

4. Assisting the patient with motivation and any problems they may be having and discussing all available resources to aid the patient in their struggle, sometimes presenting treatment options that have worked for other patients, including group sessions.

5. Arranging follow-up to insure proper adherence to techniques and to receive feedback from the patients on their success or lack of success with the program (38).

VanWarmer and Boucher recommend key messages in any type of counseling program. The first is to emphasize that tight glycemic control is the top priority for patients with diabetes, not necessarily weight management. Although weight loss may improve glycemic control, better control in some patients may lead to weight gain.

Explaining the pathophysiology of the disease is important to maintain patient compliance, as well as self-monitoring of the patient's blood glucose, which can give individuals important insight as to how the foods they are ingesting will affect their state of glycemia. Physical activity is always to be encouraged, assuming that the individual is capable of such activity. Moderate levels of physical activity for 30-45 minutes, 3-5 days/week are optimal in many exercise protocols.

It is the duration of physical activity, not the intensity, that correlates with benefit. Physical activity will reduce abdominal fat and improve insulin sensitivity and overall

Table 2

Classification of Weight and Obesity

Risk for diabetes, cardiovascular disease, and hypertension

Waist circumference

Body mass index

Class

Women <35 in

Women >35 in

Underweight

<18.5

NA

NA

NA

Normal

18.5-24.5

NA

NA

NA

Overweight

25-29.9

NA

Increased

High

Obesity

30-34.9

I

High

Very high

35-39.9

II

Very high

Very high

Extreme obesity

>39.9

III

Extremely high

Extremely high

NA, not applicable.

NA, not applicable.

cardiovascular health. The initial goal of weight management should be to reduce body weight by at least 10% from baseline (see Table 2).

Key dietary principals in attaining weight reduction must involve a deficit in caloric intake relative to caloric expenditure. Those diets that result in less insulin release, particularly in insulin-resistant individuals, have also been shown to produce more weight loss in the short term. The short-term results of many of these diets, particularly the low-carbohydrate diets, seem to be very encouraging, but the long-term results tend to be somewhat disheartening.

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