A 54-month evaluation of a popular very low calorie diet program

Journal of Family Practice, Sept, 1995 by Michael F. Walsh, Thomas J. Flynn

Background. Thirty-three percent of the adult American population over the age of 20 is obese. Many attempts to treat this increasingly occurring problem have had poor results. Both achieving weight loss and maintaining weight loss are difficult; however, current treatments appear more effective in achieving weight loss than in maintaining weight loss. The current study followed a cohort of patients to analyze weight maintenance and predictors of weight maintenance in a 26-week, formula-based, very low calorie diet program.

Methods. The study population consisted of a consecutive sample of 145 overweight patients who entered a very low calorie diet program and were contacted at 54 months after program entry.

Results. For men, the average initial weight loss at program termination was 27.2 kg (22% of original weight) and for women, 19.3 kg (18.8% of original weight). At 54 months after program entry, the average maintained loss was 5.1 kg (4.3% of original weight), at a cost of $630 per kg of long-term weight loss. There was no significant difference in maintained weight loss between men and women. Twenty-six percent of patients maintained a medically significant weight loss of 10% of entry weight. Subjects who exercised regularly maintained an average of 9.6 kg compared with 1.3 kg for nonexercisers. Those who attended the program for a longer period, and exercised more, maintained their weight better. The 54-month weight loss was similar to that seen at 30 months but markedly less than that at 18 months.

Conclusions. Very low calorie diet programs have limited long-term success that may not justify the risk of adverse effects and high costs. Longer program attendance and continued exercise are associated with improved weight maintenance. Evaluation of dietary programs should be based on a sample of consecutive patients followed for a minimum of 2 years after program completion.

Key words. Obesity; weight loss; reducing diet; very low calorie diet. (J Fam Pract 1995; 41:231-236)

The incidence of obesity in the western world is increasing and has reached epidemic proportions.[1-4] The medically obese segment of the United States population consists of the 34 million Americans who are more than 20% overweight.[5] At this level of obesity, health hazards occur, such as diabetes, arthritis, hyperlipidemia, cardiovascular disease, pulmonary disorders, certain types of cancers, and restricting disabilities.[6,7] Even though these patients are often motivated to lose weight, finding a successful and lasting treatment is an ongoing quest.[8-10] A therapeutic candidate is a very low calorie diet (VLCD).[11-13] These diets contain 800 kilocalories (3360 joules) per day or less and are usually part of a multimodal program that provides behavioral therapy, nutritional education, exercise instruction, and professional supervision. Despite the money spent on these types of programs ($1.6 billion in 1990 alone),[14] the research on long-term results is inadequate.[9,13[

The Federal Trade Commission published guidelines for substantiation of weight-loss claims. The conditions for validating claims require sampling based on all patients entering the program, monitoring results for a minimum of 2 years after program completion, and documenting the amount and duration of the average weight loss maintained.[15]

Recently, we published a study conforming to these guidelines in a 30-month follow-up evaluation of consecutive patients enrolled in a VLCD program.[16] The current report is an extended evaluation of this population at 54 months after program entry and is the largest number of successive patients treated with VLCD studied in longterm follow-up.

Methods

Study patients participated in a weight-loss clinic administered by a for-profit hospital in Orange Park, Florida. The clinic offered the OPTIFAST Core Program (Sandoz Nutrition Co, Minneapolis, Minn). Details of the program have been previously described elsewhere.[17] The program is designed to last 26 weeks. After an introductory week, patients consume a high-protein supplement of either 420 kilocalories (1764 joules) or 800 kilocalories (3360 joules) for the next 12 weeks. Over the subsequent 6 weeks, patients are gradually reintroduced to food. During the final 7 weeks, patients consume a regular diet of 1200 to 1400 kilocalories (5040 to 5880 joules). During the 26-week program, closed groups of 12 to 18 patients meet weekly for I hour of behavioral modification, nutritional education, exercise instruction, and emotional support. A supervising physician takes an initial history, does a physical examination, and sees the patient weekly for 20 weeks of the program. Laboratory testing is done at the beginning of the program and during the low-calorie portion of the program.

We reviewed the charts of 306 consecutive patients entering the OPTIFAST program for demographic characteristics, height, weight at time of entry, length of program attendance, and weight at time of program exit. No patients were excluded during the initial screening process. At 30 months after program entry, we surveyed these patients. Results were published on the 255 responding patients.[16]