Effects of consumption of dairy products on body weight and composition in adults: Asystematic review and meta-analysis of randomized controlled clinical trials

Although many observational and experimental studies have investigated the effect of dairy consumption on body weight and composition، the results are inconsistent. This systematic review and meta-analysis was conducted to summarize the available evidence obtained from randomized controlled trials (RCTs) regarding the effect of dairy consumption on body weight، fat mass، lean body mass and waist circumference (WC) in adults. PubMed، ISI Web of Science، SCOPUS، Science Direct and EMBASE were searched from January 1960 to October 2011 for the relevant English and non-English publications. Sixteen studies were finally selected for the systematic review and fourteen were included in the meta-analysis. The number of studies on weight، body fat mass، leans body mass and WC included finally in the review was 14، 12، 6 and 8، respectively. Overall، the mean difference for the effect of dairy consumption on body weight was -0. 61 kg (95% CI: -1. 29، 0. 07، P=0. 08). As compared to the respective control values، increased dairy intake could result in an additional reduction of 0. 72 kg (95% CI: -1. 29، -0. 14، P=0. 01) in fat mass، an additional increase of 0. 58 kg (95% CI: 0. 18، 0. 99، P>0. 01) in lean body mass، and an additional reduction of 2. 19 cm (95% CI: -3. 42، -0. 96، P-value < 0. 001) in WC. Subgroup analysis revealed that increasing dairy intake without energy restriction in both the intervention and control groups could not significantly affect weight، body fat mass، lean body mass or WC. Consumption of a high-dairy weight loss diet would lead to anadditional 1. 29 kg (95% CI: -1. 98، -0. 6، P<0. 001) weight loss، an additional 1. 11 kg (95% CI: -1. 75، -0. 47، P=0. 001) reduction in body fat mass، an additional increase of 0. 72 kg (95% CI: 0. 12، 1. 32، P=0. 02) in lean body mass، and an additional reduction of 2. 43 cm (95% CI: -3. 42، -1. 44، P<0. 001) in WC، compared to the respective control values. Increased dairy consumption without energy restriction might not lead to a significant change in body weight or body composition. As compared to common weight reduction diets، inclusion of dairy products in energy-restricted weight loss diets significantly affects body weight، body fat mass، lean body mass and waist circumference.