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Research Area: Body Weight/Satiety

Intake of Nuts or Nut Products Does Not Lead to Weight Gain, Independent of Dietary Substitution Instructions: A Systematic Review and Meta-Analysis of Randomized Trials.

Guarneiri, L.L., J.A. Cooper, 2020. Intake of Nuts or Nut Products Does Not Lead to Weight Gain, Independent of Dietary Substitution Instructions: A Systematic Review and Meta-Analysis of Randomized Trials. Adv Nutr. 00:1–18.

Several clinical interventions report that consuming nuts will not cause weight gain. However, it is unclear if the type of instructions provided for how to incorporate nuts into the diet impacts weight outcomes. We performed a systematic review and meta-analysis of published nut-feeding trials with and without dietary substitution instructions to determine if there are changes in body weight (BW) or composition. PubMed and Web of Science were searched through 31 December 2019 for clinical trials involving the daily consumption of nuts or nut-based snacks/meals by adults (≥18 y) for >3 wk that reported BW, BMI, waist circumference (WC), or total body fat percentage (BF%). Each study was categorized by whether or not it contained dietary substitution instructions. Within these 2 categories, an aggregated mean effect size and 95% CI was produced using a fixed-effects model. Quality of studies was assessed through the Cochrane risk-of-bias tool. Fifty-five studies were included in the meta-analysis. In studies without dietary substitution instructions, there was no change in BW [standardized mean difference (SMD): 0.01 kg; 95% CI: −0.07, 0.08; I 2 = 0%] or BF% (SMD: −0.05%; 95% CI: −0.19, 0.09; I 2 = 0%). In studies with dietary substitution instructions, there was no change in BW (SMD: −0.01 kg; 95% CI: −0.11, 0.09; I 2 = 0%); however, there was a significant decrease in BF% (SMD: −0.32%; 95% CI: −0.61%, −0.03%; I 2 = 35.4%; P < 0.05). There was no change in BMI or WC for either category of studies. Nut-enriched diet interventions did not result in changes in BW, BMI, or WC in studies either with or without substitution instructions. Slight decreases in BF% may occur if substitution instructions are used, but more research is needed. Limitations included varying methodologies between included studies and the frequency of unreported outcome variables in excluded studies.

Changes in nut consumption influence long-term weight change in US men and women.

Liu, X., Y. Li, M. Guasch-Ferre, W.C. Willett, J.-P. Drouin-Chartier, S.N. Bhupathiraju, D.K. Tobias, 2019. Changes in nut consumption influence long-term weight change in US men and women. bmjnph 2019;0:1–10. doi:10.1136/bmjnph-2019-000034.

Background: Nut consumption has increased in the US but little evidence exists on the association between changes in nut consumption and weight change. We aimed to evaluate the association between changes in total consumption of nuts and intakes of different nuts (including peanuts) and long-term weight change, in three independent cohort studies. Methods and Findings: Data collected in three prospective, longitudinal cohorts among health professionals in the US were analysed. We included 27, 521 men (Health Professionals Follow-up Study, 1986 to 2010), 61,680 women (Nurses’ Health Study, 1986 to 2010), and 55,684 younger women (Nurses’ Health Study II, 1991 to 2011) who were free of chronic disease at baseline in the analyses. We investigated the association between changes in nut consumption over 4-year intervals and concurrent weight change over 20–24 years of follow-up using multivariate linear models with an unstructured correlation matrix to account for within-individual repeated measures. 21,322 individuals attained a body mass index classification of obesity (BMI ≥30 kg/m2) at the end of follow-up. Average weight gain across the three cohorts was 0.32 kg each year. Increases in nut consumption, per 0.5 servings/ day (14 g), was significantly associated with less weight gain per 4-year interval (p<0.01 for all): −0.19 kg (95% CI -0.21 to -0.17) for total consumption of nuts, -0.37 kg (95% CI -0.45 to -0.30) for walnuts, -0.36 kg (95% CI -0.40 to -0.31) for other tree nuts, and -0.15 kg (95% CI -0.19 to -0.11) for peanuts. Increasing intakes of nuts, walnuts, and other tree nuts by 0.5 servings/day was associated with a lower risk of obesity. The multivariable adjusted RR for total nuts, walnuts, and other tree nuts was 0.97 (95% CI 0.96 to 0.99, p=0.0036), 0.85 (95% CI 0.81 to 0.89, p=0.0002), and 0.89 (95% CI 0.87 to 0.91, p<0.0001), respectively. Increasing nut consumption was also associated with a lower risk of gaining ≥2 kg or ≥5 kg (RR 0.89–0.98, p<0.01 for all). In substitution analyses, substituting 0.5 servings/day of nuts for red meat, processed meat, French fries, desserts, or potato, chips (crisps) was associated with less weight gain (p<0.05 for all). Our cohorts were largely composed of Caucasian health professionals with relatively higher socioeconomic status; thus the results may not be generalisable to other populations. Conclusion: Increasing daily consumption of nuts is associated with less long-term weight gain and a lower risk of obesity in adults. Replacing 0.5 servings/day of less healthful foods with nuts may be a simple strategy to help prevent gradual long-term weight gain and obesity.

Daily consumption of pistachios over 12 weeks improves dietary profile without increasing body weight in healthy women: A randomized controlled intervention.

Fantino, M., B. Cé., M. Fréé, F. Bellisle, 2019. Daily consumption of pistachios over 12 weeks improves dietary profile without increasing body weight in healthy women: A randomized controlled intervention. Appetite. doi: https://doi.org/10.1016/j.appet.2019.104483.

Dietary guidelines around the world recommend the regular intake of nuts because of their nutrient contribution to the diet and reported health benefits. However, consumers are often reluctant to include nuts in their diet due to the high caloric density of nuts. In a 12-week randomized, controlled intervention, we investigated how adding a pistachio portion to the daily diet affects body weight and composition, satiety, energy and nutrient intake. Sixty healthy pre-menopausal women who did not typically consume nuts were randomly assigned to a control or an experimental groups. Experimental participants (n = 30) consumed 44 g (250 kcal) pistachios mid-morning while controls (n = 30) maintained their current eating habits for 12 weeks. Ad libitum food intake and appetite sensations following the pistachio portion were assessed in all participants before and after the intervention in four 2-consecutive-day test sessions (under laboratory and then free-living conditions). Body weight and composition (DXA) were unchanged in both groups after 12 weeks. Pre- and post-intervention tests showed that ad libitum intake adjusted to the pistachio portion, mostly via reduced intakes of carbohydrates and starch, in parallel with decreased hunger and increased satiety following the morning snack. Intakes of MUFA, PUFA, linoleic acid, thiamin, pyridoxine, copper, manganese, and zinc were significantly higher among women consuming the pistachio snack, in spite of compensatory adjustments in intake. In conclusion, daily intake of 44 g pistachios improved nutrient intake without affecting body weight or composition in healthy women. The additional calories provided by the pistachios induced satiety and sufficient adjustment of intake to prevent body weight changes.

A randomized controlled pilot study to assess effects of a daily pistachio (Pistacia Vera) afternoon snack on next-meal energy intake, satiety, and anthropometry in French women.

Carughi, A., F. Bellisle, A. Dougkas, A. Giboreau, M.J. Feeney, J. Higgs, 2019. A randomized controlled pilot study to assess effects of a daily pistachio (Pistacia Vera) afternoon snack on next-meal energy intake, satiety, and anthropometry in French women. Nutrients. Apr 2;11(4). pii: E767. doi: 10.3390/nu11040767.

Including nuts in the diet improves appetite control and does not lead to weight gain. However, for pistachios, evidence from randomized intervention studies is limited and there are no data on the effect of pistachios on satiety. The objective of this study was to assess the effect of daily consumption of pistachios as an afternoon snack on satiety, self-reported energy, self-reported nutrient intake, body weight, and body composition. This randomized controlled pilot study included two parallel groups of 30 healthy French women, in a free-living setting. For four weeks, groups were instructed to consume either 56 g (1318 kJ) of pistachios or 56 g of isoenergetic/equiprotein savory biscuits as an afternoon snack. Evening energy intake, changes in anthropometric measures, and daily intake of energy and selected nutrients were assessed. Visual analogue scales (VAS) were used to rate hunger, fullness, desire to eat, and prospective consumption. Satiety effects were not different between groups, as assessed by evening energy intake or VAS scores. Consuming pistachios or biscuits had no impact on body weight. Thiamin, vitamin B6, copper, and potassium intakes were significantly higher in the pistachio group. Consuming pistachios or biscuits as an afternoon snack resulted in similar post-snack food intake and subjective feelings of satiety. A daily pistachio snack for a month did not affect body weight or composition but it did improve micronutrient intake.