SB Heymsfield, CAJ van Mierlo, HCM van der Knaap, M Heo and HI Frier
International Journal of Obesity (2003) 27, 537-549
The studies included were randomized and controlled. They included study participants with BMI over 25 kg/m2 and over age 18 years. In these studies, one or two meals were replaced with meal replacement for at least 3 months and total calorie intake was 800 to 1600 kcal per day.
Although millions of overweight and obese people use meal replacements, no systematic assessment has previously been carried out to determine how safe and effective meal replacements are for weight management. The purpose of this study was to apply analytical methods such as meta-analysis and pooling analysis to review currently available studies that have examined safety and effectiveness using a PMR plan (a program with 800-1600 kcal in which 1-2 meal replacements are included) for treatment together with ordinary food for weight loss and long-term weight Management.
Medline, Embase and the Cochrane Clinical Trial Register were searched for studies conducted between 1960 and Jan. 20, 2001, and 30 potential studies were found. Six of these studies met all inclusion criteria and used liquid meal replacement. In these studies participants were randomized to a partial meal replacement plan (PMR) or a conventional reduced calorie diet (RCD) with the same calorie content. The authors from all six studies were contacted and asked to provide data for analysis. Data from all 6 studies were gathered and evaluated.
Study participants in the PMR and RCD groups demonstrated significant weight loss after both 3 and 12 months. All analytical methods showed that the group that used meal replacements (PMR) achieved significantly greater weight loss than the group with the conventional low-calorie diet (RCD). Depending on analysis and follow-up, the PMR group lost 7-8% body weight and the RCD group 3-7% body weight after 12 months.
Meta-analysis demonstrated that the PMR group achieved a further weight loss of 2.54 kg (p<0.01) and 2.43 kg (p=0.14) at 3 and 12 months, respectively, compared with the RCD group. Pooling analysis demonstrated a further weight loss in the PMR group of 2.54 kg (P<0.01) and 2.63 kg (P<0.01), respectively, over the same time periods, compared with the RCD group. Risk factors for diseases associated with overweight and obesity improved through weight loss in both groups. The dropout rate was equivalent in the groups after 3 months, but significantly lower in the PMR group after 12 months.
The six studies evaluated through meta-analysis and pooling analysis showed that the effectiveness of weight loss with meal replacement was equivalent or significantly greater than with conventional low-calorie diet. One fifth of the study population had diabetes at baseline and no difference was found in weight loss between patients with and without diabetes at 3 months. After 1 year, however, diabetic patients failed to maintain weight loss to the same extent as those without diabetes. In addition, the relapse rate after 12 months was higher among diabetics than among non-diabetics in both treatment groups, almost 80%. Earlier weight-loss studies with diabetics have also shown less long-term weight loss compared with non-diabetics. Less weight loss is expected among patients with diabetes owing to the disease and the need for insulin.
An important question is why treatment with meal replacement provides improved weight management. A body of literature supports the effectiveness of a structured weight loss plan. According to Wing and Jeffrey, patients who use meal replacements achieve improved behavioral patterns and increased knowledge of nutrition, and also eat more regularly and snack less. Meal replacement in a weight loss plan reduces food choices, replaces energy-dense poor food choices and instead provides reduced calorie and nutrient-dense Options.
This first systematic evaluation of randomized controlled studies using treatment with meal replacement for weight management shows that these measures can safely and effectively provide significant sustainable weight loss and improve weight-related risk factors and diseases.
This study also provides guidance and can serve as a basis for using meal replacement in treatment programs for weight loss and weight management.