Inverse association of long-term nut consumption with weight gain and risk of overweight/obesity: a systematic review

Nuts contain a variety of nutrients and bioactive compounds that are capable of promoting metabolic health. However, due to their high energy density, concerns have been raised that nut consumption in the long term may contribute to weight gain. This systematic review summarizes the findings of prospective studies regarding the relationship between long-term nut consumption and obesity. Searches were conducted up through February 2018, using the PUBMED, EMBASE, and SCOPUS databases with the relevant MeSH terms and phrases. This systematic review included prospective cohort studies investigating the relationship between consumption of total nut and/or nut subtypes with changes in weight, body mass index (BMI), and waist circumference (WC), as well as the risk of overweight/obesity, with follow-up duration ≥1-year. Out of a total of 1580 papers that were initially examined, 6 met the inclusion criteria. Four out of the 6 studies showed an inverse association between nut consumption (typically at the dosages of ≥1 to 2 servings per week) and weight gain and risk of overweight/obesity. The remaining 2 studies evaluated the association between nut intake and changes in WC. From these 2 studies, only one study reported a significant inverse association. Overall, evidence from limited cohort studies demonstrated that long-term nut intake was associated with less weight gain and reduced risk of overweight/obesity. Whether such findings are generalizable to racially diverse ethnic groups, individuals of low socioeconomic status, and populations in developing countries should be addressed in future studies.