Pasta consumed in the context of a low-glycemic index (GI) diet does not contribute to weight gain and does result in modest weight loss compared with a higher-GI diet, at least over a median follow-up of 12 weeks, a systematic review and meta-analysis indicates.
“Pasta is an important example of a food that is considered a refined carbohydrate but has a low GI,” Laura Chiavaroli, PhD, from the University of Toronto, Ontario, Canada, and colleagues write. “Lower-GI diets may result in greater body weight reduction compared with higher-GI diets because lower-GI foods have been shown to be more satiating and delay hunger and decrease subsequent energy intake,” they add. “[E]ncouragement of the consumption of pasta in the context of a low-GI dietary pattern does not cause harm and may even lead to spontaneous weight loss,” study authors reaffirm.
The study was published April 2 in BMJ Open.
Investigators were unable to identify any randomized controlled trial lasting 3 weeks or longer in which the effect of pasta alone was evaluated on measures of global or regional body fat. However, they did identify 32 trials involving 2448 adults that assessed the effect of pasta on global and regional indices of body fat in the context of low-GI dietary patterns. Measures of global body fat included weight and body mass index; measures of regional body fat included waist circumference, waist-to-hip ratio, and sagittal abdominal diameter adiposity.
“Pooled analyses showed pasta in the context of low-GI dietary patterns had the effect of reducing body weight by −0.63 kg (95% [confidence interval], −0.84 to −0.42 kg; P<0.001) compared with higher-GI control diets with no evidence of heterogeneity,” the investigators observe. Pooled analyses again support a beneficial effect of pasta within the context of a low-GI diet on body mass index, where body mass index dropped by 0.26 kg/m2 (95% confidence interval, −0.36 to −0.16 kg/m2; P < .001) compared with higher-GI control diets.
In contrast, there was no effect from the same diet on waist circumference, waist-to-hip ratio, or sagittal abdominal diameter compared with higher-GI diets. Removal of two studies from the meta-analysis in which the effect of diet on waist circumference in the context of a low-GI diet was evaluated did show a significant effect from pasta on waist circumference, where the mean difference was a loss of approximately 60 cm compared with a higher-GI diet. “These findings were robust across subgroups,” the researchers point out, “[and they] 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,” they state.
Weight loss at 0.63 kg with pasta consumed in a low-GI context was similar among participants in trials lasting fewer than 24 weeks and those in trials lasting 24 weeks and longer. “This finding is of particular relevance since many dietary studies are successful in demonstrating weight loss in the short term but not over the long term,” the investigators observe. They acknowledge that pasta can vary widely not only in shape but also in ingredients and in processing techniques.
Despite slight variations in glycemic response brought about by these differences, “glycaemic responses are still lower [with pasta] compared with a control, for example, white bread,” they point out. They also point out that pasta has a similar GI as other fiber-rich carbohydrates such as steel cut oats, and its GI is actually lower than the GI of more commonly consumed foods such as breakfast cereals and skin-on potatoes. Most people eat white wheat pasta, the authors acknowledge.
Nevertheless “white wheat pasta…has a higher micronutrient content compared with other white wheat products like bread since it contains the aleurone layer, which is preserved as a result of the use of harder wheat [such as] durum wheat,” they state. Even when bread is made out of durum wheat, “pasta retains a lower glycaemic response primarily because of the processing techniques used in pasta making,” they indicate.
Pasta and Metabolism
Asked to comment on the study, Elena Philippou, PhD, assistant professor of nutrition-dietetics, University of Nicosia, Cyprus, told Medscape Medical News she agrees with the conclusions and the implications of the findings, given that they come from a highly reputable group of researchers from the University of Toronto. Philippou is also a visiting lecturer in nutrition-dietetics at King’s College London, United Kingdom. “Consumption of pasta as part of a low-GI diet would not lead to weight gain and may even contribute to slight weight loss,” she concurred.
This might be because consumption of pasta as part of a low GI-diet such as the Mediterranean diet may have a positive effect on increasing satiety as well as possibly beneficial effects on glucose and insulin metabolism, she added, and thus may help reduce or prevent insulin resistance and accumulation of body fat, especially visceral fat. “Of course, it’s important that the general public understands that this doesn’t mean that one can eat as much pasta as they want and they will not gain weight,” Philippou stressed.
“Neither does it mean that they can serve pasta in cream and not gain weight either,” she added. “Everything in moderation and as part of a healthy low-GI diet plan,” Philippou concluded.
Chiavaroli has disclosed no relevant financial relationships. The remaining authors have disclosed a variety of financial relationships with companies and organizations including Glycaemic Index Laboratories, Advanced Food Materials Network, Agriculture and Agri-Foods Canada, Almond Board of California, American Pistachio Growers, Barilla, California Strawberry Commission, Calorie Control Council, Canadian Institutes of Health Research, Canola Council of Canada, International Nut and Dried Fruit Council, International Tree Nut Council Research and Education Foundation, Loblaw Brands Ltd, Pulse Canada, Saskatchewan Pulse Growers, Unilever, California Walnut Council, American Peanut Council, Unico, Primo, Loblaw Companies, Quaker, Pristine Gourmet, Kellogg Canada, WhiteWave Foods, Bayer, General Mills, International Tree Nut Council, Nutrition Foundation of Italy, Oldways Preservation Trust, Orafti, Paramount Farms, Peanut Institute, Pulse Canada, Sabra Dipping Co, Saskatchewa Pulse Growers, Sun-Maid, Tate & Lyle, and McCormick Science Institute. A complete list can be found on the journal’s website. Philippou is the editor of The Glycemic Index: Applications in Practice, but otherwise has disclosed no relevant financial relationships.
BMJ Open. 2018;8:e019438. Abstract
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