Study Results

Excerpts from:
A Comparison of Medically Supervised and Unsupervised Approaches to Weight Loss and Control

Harvard Medical School
George L. Blackburn, MD, PhD

As presented to the National Institutes of Health and published in the Annals of Internal Medicine

Overview

The lack of medical supervision in weight loss programs increases the potential for health problems, and even minimal physician involvement can enhance outcomes.

In published clinical trials, the absence of contact with health professionals among control group participants may account in part for their poor success at weight loss or for their weight gain.

Smaller trials examining the value of physician advice and encouragement among dieting patients have shown promising results. Physicians should monitor the health of obese and overweight patients during and after weight loss as is appropriate for the patient, depending on caloric levels, rate of weight loss, weight-loss goals, and intercurrent health events.

Medical supervision is necessary for patients on very-low-calorie diets, for severely obese patients (body mass index >35), and for patients with other health problems.

Only recently have the metabolic disorders associated with clinically significant obesity, such as syndrome X and its individual components (hyperinsulinemia, dyslipidemia, hypertension, and hyperuricemia), alerted health care professionals to the need for medical intervention in the treatment of obesity.

Recommendations for Medically Supervised Programs:
Low-Calorie Diets

The AMA's Council on Scientific Affairs recognized the use of low-calorie diets (LCDs), which provide more than 800 calories per day. Low-calorie diets represent the most common and, when compliance is monitored, safest treatment of obesity. Compliance with LCDs usually ensures that weight loss does not exceed 0.5% to 1.0% of initial body weight per week, which is recommended as safe and acceptable by the U.S. Dietary Guidelines.

When monitored by a physician and supervised by a registered dietitian or clinical nutritionist, the LCD should be sufficient for most patients to promote a 10% to 15% weight loss over 10 to 20 weeks. This level of weight loss results in most of the health benefits associated with weight loss. Due to the level of carbohydrate intake, these regimens are rarely associated with the consequences of starvation metabolism sometimes encountered with Very Low Calorie Diets.

Physicians must become involved in obesity treatment when the patient has concurrent disease or other risk factors for fatal complications. Overweight persons have an increased risk for morbidity and death that is proportional to their degree of obesity and that also increases with age and the presence of additional disease. A body mass index (BMI) of 25 to 30 kg/m2 (independent of concurrent illness) may be described as incurring low risk, 30 to 35 as moderate risk, 35 to 40 as high risk, and anything greater than 40 as very high risk.

Recommendations for Medical Monitoring of Unsupervised Programs

At any given time, an estimated 65 million Americans diet to lose weight, and many of these persons participate in commercial programs or consume over-the-counter products. Recent reports of gallstone formation (requiring cholecystectomies), cardiac arrhythmias, and even death have generated concern regarding the safety of some unsupervised commercial programs. To a large extent, the lack of medical supervision and the lack of guidelines to indicate when medical supervision is necessary are responsible for diet-related morbidity and death.

Deviation from recommended dietary guidelines (for example, too little fat, no meal with at least 10 g fat, excessive protein) can lead to medical problems including the formation of gallstones.

Persons planning to lose weight on their own should see their physician for a baseline physical examination to identify any underlying diseases and to discuss weight loss strategies and goals. In addition to completing a thorough examination and medical history, physicians should collect information on the patient's nutritional history as well as on the waist and hip circumferences (to monitor reduction in risk through changes in waist-to-hip ratio). Weight loss should not exceed 1% of body weight per week. Physician visits should subsequently be scheduled after any 10% change in body weight (loss or gain) and whenever a change in health status is noted. If fatigue, muscle weakness, lightheadedness, or new health problems arise, the physician should be notified promptly.

Published Comparison of Medically Supervised and Unsupervised Programs

Although no large, randomized, clinical trials have specifically compared weight loss results between patients receiving medical supervision and those not receiving supervision, data in the literature suggest a benefit for physician involvement.

Educating the physicians, increasing the frequency of visits, and taking opportunities to educate the patients…involved little extra expense or effort…and frequent visiting is important in encouraging weight loss.

In addition to the significantly greater weight loss noted among patients in the intervention group, most controls gained weight. At baseline, those randomized to the control group could be assumed to have equal motivation to lose weight as those randomized to intervention groups (although, in some cases, controls are specifically told not to diet or to make other lifestyle changes, and in other studies they are considered to be "self-help" patients, particularly if their participation in screening and enrollment has heightened their awareness of the value of weight control in improving health or if they receive educational materials for home use).

In one study, we compared the outcome of 187 obese hypertensive patients using medically supervised VLCD and LCD programs. Those receiving the VLCD (a protein-sparing modified fast) experienced a 17% reduction in initial body weight, whereas those receiving the LCD (a balanced deficit diet) lost 12% of initial body weight. During the 6 months of active maintenance (medically supervised), patients regained only 5% (VLCD) and 2% (LCD) of their body weight. For the next 18 months, patients had no clinic contact and came in for milestone visits only. During this period, patients regained weight at a faster rate, maintaining only 41% (VLCD) and 38% (LCD) of their initial weight loss at 18 months.

In a study of 49 overweight hypertensive patients, Ramsay and colleagues compared the effectiveness of physician advice alone, physician advice plus written and oral diet instructions (given by a physician), and physician referral to a dietitian (who was unaware of the study) for instruction on body weight and blood pressure. After this encounter (advice, diet sheet, dietitian), management during the 1 year of follow-up was routine and voluntary until the second and last data collection visits (9 to 15 months after the baseline visit). The results indicated that intervention of any kind had some effect, with one third of all patients losing 13 lbs or more 1 year after randomization.

Other Evidence That Physician Supervision Makes a Difference

Even if physician supervision is not required for weight control, evidence suggests that physician participation could make a difference in patient outcome. Published reports indicate that physicians can influence patient behavior with regard to smoking cessation. Similarly, patient outcome in the treatment of hypertension improved after a single physician tutorial, which led to more time spent in patient education. Cohen and associates, as described above, showed the ability of physicians to make a difference in body weight and clinical outcome.

Recent reviews of the doctor-patient relationship indicate that it provides many opportunities to encourage behavioral change, to reinforce positive changes (for example, improved dietary practices, increased activity, and steady weight loss and control), and to encourage use of community resources through appropriate referrals to outside agencies and facilities (for example, local registered dietitian, acceptable supervised and unsupervised weight-loss programs). Patients appear to be willing to listen to advice from their physicians, with some authorities reporting that people expect such advice on maintaining health.

Specific data regarding the success and cost-effectiveness of physician involvement in weight-loss attempts should come from the Trial of Antihypertensive Interventions and Management (TAIM) study. The investigators reported that a weight loss of 10 lbs or more lowered blood pressure in a manner similar to low-dose drug therapy and potentiated drug effect. These 6-month results and the accompanying summary of other hypertensive trials suggest that physicians can assist in producing the modest amount of weight loss (that is, 10%) required to improve health.