M Noakes, PR Foster, JB Keogh and PM Clifton.
The Journal of Nutrition, 2004 Aug;134(8):1894-9.
66 Australian patients, 20-65 years, BMI 27-40, Tg > 2.0 mmol
Meal replacements are generally used as a weight loss strategy, but their efficacy outside controlled clinical studies is unknown. Weight loss programs that use meal replacements have been criticized for increasing the risk of inadequate nutrients and providing a skewed energy distribution of the diet. The aim of the study was to compare the effect of meal replacements (MR) as a nutritionally sound weight-loss strategy with a structured low-calorie and low-fat diet (C) under unmonitored conditions, in which participants only receive written advice.
Study and method:
Patients were randomized into two groups. One group was treated with meal replacement (MR) and one group followed a low-calorie, low-fat diet (C) containing 6000 kJ per day for 3 months (stage 1) and subsequently an additional 3 months (stage 2). The MR group received 2 MR per day, supplemented by one dinner (low-fat) and at least 5 portions of fruit or vegetables per day. Group C received vouchers to shop for food. A 3-day food diary was recorded by both groups every 4 weeks, which was not assessed by a dietician and participants did not receive any feedback on their dietary intake.
Participants were weighed every 14 days and blood samples were taken to measure serum folic acid and plasma carotenoids, as an index for fruit and vegetable consumption, and plasma homocysteine levels as a marker associated with changes in intake of folic acid and weight loss. Participants completed a quality of life questionnaire to assess attitudes toward the Treatment.
Results and discussion:
In all, 55 participants completed stage 1 and 42 completed stage 2. Weight loss was equivalent in both groups. Weight loss was 6.6 ± 4.2 kg (6.3%) in the MR group and 6.6 ± 3.4 kg (6.9%) in the C group after 3 months, a significant result. After 6 months total weight loss was 9.0 ± 6.9 kg (9.4%) in the MR group and 9.2 ± 5.1 kg (9.3%) in the C group, also a significant result. Weight loss showed a difference over time, but not between the groups.
Serum folic acid and beta-carotene plasma levels were higher in the MR group and plasma homocysteine fell in both groups (p<0.005). Fiber intake was higher in the C group (p<0.002) and calcium intake was higher in the MR group (p<0.001). Weight loss in the MR group and the C group was equally effective after both 3 and 6 months. Nutrient intake was also equivalent in both groups (except fiber).
The MR group found the diet easier to follow and showed higher significance concerning questions of understanding and compliance with written dietary guidelines (p<0.005).Calcium intake was higher in the MRI group since it was milk-based. Weight loss diets are often associated with increased bone resorption among obese adults, so the increased potassium intake with meal replacements is beneficial. The negative aspect to meal replacements was lower fiber intake than in the conventional low-calorie, low-fat diet. Fiber intake for both diets was lower than the RDA. but higher than the average intake in Australia.
Participants in this study found meal replacements to be simple to use and manageable, even when dining out. Use and compliance with the diet were therefore good, which supports the effectiveness of using meal replacement in a long-term diet. These results support use of meal replacement in a long-term weight loss program and lend support to nutritional adequacy, when used appropriately.
Our conclusion is that meal replacement is as effective for weight-loss as a conventional low-calorie, low-fat diet when followed for both 3 and 6 months. Nutritional adequacy was similar (except for fiber). Compliance and convenience were important and participants found the diet with meal replacement easier to follow.