COMPARATIVE EFFECTIVENESS OF TWO REDUCED CALORIE DIETS AND THE INFLUENCE OF A LIQUID FORMULA NUTRITIONAL SUPPLEMENT IN WEIGHT REDUCTION

Alternating the daily caloric goals in a diet regimen may result in more weight loss and diet compliance than do traditional fixed-calorie diets. The intermittent use of a liquid nutritional supplement in place of food may also increase compliance and thus weight loss. To test these hypotheses, 60 women, aged 22-46, with a Body Mass Index between 24 and 43, were assigned by a quasi-random procedure to one of four treatment conditions in a 2 x 2 factorial design. Half the subjects alternated daily between caloric goals of 800 and 1200 kcal (alternating diet); the remaining half had a daily goal of 1000 kcal (fixed-calorie diet). Half the subjects in each diet group used a liquid nutritional supplement every other day in place of food to reach their caloric goal while the other half used food only. All four treatments lasted thirteen weeks, and all subjects received a group behavioral treatment program. The fixed diet with supplement was found to provide significantly less weight loss than the other treatment conditions only when dropouts were included in the analyses. Otherwise there was no difference in weight loss among the four treatment conditions. Attrition in the fixed-calorie plus supplement condition may have reflected difficulties in complying with that regimen. Supplement use was effective in increasing compliance with diet requirements, but did not clearly lead to greater weight loss. Average caloric intake and self-monitoring through food records also did not clearly contribute to weight loss. Subjects who rated their diet as more difficult lost less weight than did those who rated their diet as less difficult. High exercisers lost more weight than low exercisers. Limitations of the design and its implementation are discussed, as are suggestions for future research.