Key Findings
This systematic reviews and meta-analyses reviewed the evidence of the effect of pasta on body weight outcomes and included a comprehensive search and a large number of randomised controlled trials which provide the best protection against bias. Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach was used to evaluate the strength and quality of the evidence. There was evidence of unexplained inconsistency among the trial estimates for waist circumference and body fat. The generalisability of the results is called into question for all body weight and adiposity outcomes, as the available trials only assessed pasta in the context of low-glycaemic index dietary patterns (none assessed the effect of pasta alone or in the context of other dietary patterns and most did not quantify the amount of pasta consumed).
The primary pooled analysis demonstrated that pasta in the context of low-GI dietary patterns did not contribute to weight gain, resulting in a significant weight loss of −0.63 kg when compared with diets higher in GI over a median follow-up of 12 weeks. The findings did not differ by metabolic phenotype in those who were overweight or obese or had diabetes, which is noteworthy since these are populations who would benefit from weight management strategies. There was also no effect modification by the energy balance of the design such that the weight loss was seen even under conditions of neutral energy balance (in which participants were instructed to consume dietary advice ad libitum). The mechanism by which pasta in the context of low-GI dietary patterns lead to weight loss even under conditions of ad libitum dietary advice is unclear.
In conclusion, the available evidence from RCTs does not allow conclusions that pasta consumed in the context of low-GI dietary patterns has an adverse effect on body weight and adiposity outcomes of importance in the prevention and management of overweight and obesity. On the contrary, pasta in the context of low-GI dietary patterns reduces body weight and BMI compared with higher-GI dietary patterns. Further research is needed to improve the estimates. There is also a need for more randomised trials of >1-year diet duration to clarify whether the lack of harm for pasta in the context of low-GI dietary patterns will translate into meaningful long-term benefits. Other randomised trials should focus on whether pasta will have similar effects in the context of other ‘healthy’ dietary patterns such as a Mediterranean diet.
ABSTRACT
OBJECTIVE: Carbohydrate staples such as pasta have been implicated in the obesity epidemic. It is unclear whether pasta contributes to weight gain or like other low-glycaemic index (GI) foods contributes to weight loss. We synthesised the evidence of the effect of pasta on measures of adiposity. DESIGN: Systematic review and meta-analysis using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach. DATA SOURCES: MEDLINE, Embase, CINAHL and the Cochrane Library were searched through 7 February 2017. ELIGIBILITY CRITERIA FOR SELECTING STUDIES: We included randomised controlled trials ≥3 weeks assessing the effect of pasta alone or in the context of low-GI dietary patterns on measures of global (body weight, body mass index (BMI), body fat) and regional (waist circumference (WC), waist-to-hip ratio (WHR), sagittal abdominal diameter (SAD)) adiposity in adults. DATA EXTRACTION AND SYNTHESIS: Two independent reviewers extracted data and assessed risk of bias. Data were pooled using the generic inverse-variance method and expressed as mean differences (MDs) with 95% CIs. Heterogeneity was assessed (Cochran Q statistic) and quantified (I2 statistic). GRADE assessed the certainty of the evidence. RESULTS: We identified no trial comparisons of the effect of pasta alone and 32 trial comparisons (n=2448 participants) of the effect of pasta in the context of low-GI dietary patterns. Pasta in the context of low-GI dietary patterns significantly reduced body weight (MD=-0.63 kg; 95% CI -0.84 to -0.42 kg) and BMI (MD=-0.26 kg/m2; 95% CI -0.36 to -0.16 kg/m2) compared with higher-GI dietary patterns. There was no effect on other measures of adiposity. The certainty of the evidence was graded as moderate for body weight, BMI, WHR and SAD and low for WC and body fat. CONCLUSIONS: Pasta in the context of low-GI dietary patterns does not adversely affect adiposity and even reduces body weight and BMI compared with higher-GI dietary patterns. Future trials should assess the effect of pasta in the context of other ‘healthy’ dietary patterns.
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