Despite their caloric density, certain nuts may also aid weight control. A recent review of literature in 2018 evaluates the potential impact of nuts and seeds on gut microbiota and their role in weight management and obesity prevention. Nuts provide prebiotic fiber which affects energy regulation. The researchers suggest that nuts may aid in weight control through the maintenance of gut barrier integrity, anti-inflammatory effects and the production of short chain fatty acids such as butyrate. Clinical trials are advised to further investigate microbiota metabolites and how they aid in obesity prevention (1).Results from the EPIC-PANACEA study also suggests that nut intake may reduce risk for weight gain over time. In a study which included 373,293 men and women, 25-70 years old, regular consumption of peanuts and other nuts was estimated from validated, country-specific questionnaires. Body weight was taken at recruitment and self-reported five years later. Habitual intake of nuts including peanuts, together defined as nut intake, was estimated from country-specific validated dietary questionnaires. Body weight was measured at recruitment and self-reported 5 years later. The association between nut intake and body weight change was estimated using multilevel mixed linear regression models with center/country as random effect and nut intake and relevant confounders as fixed effects. Despite average weight gain of 2.1 kg over 5 years, subjects who consumed more nuts had less weight gain and a 5% lower risk of becoming overweight (2).What’s a serving size?The AHA suggests four servings (small handfuls) of unsalted nuts/week, but serving sizes, type of fat, and calories for nuts vary (3). A 1 and ½ ounce serving of nuts is considered one serving. 

• For almonds, this is roughly 30 to 35 nuts.
• For Brazil nuts, it's 12 nuts.
• 18 hazelnuts count as a serving.
• For walnuts and pecans, a serving size is roughly 21 halves.
• Since peanuts are a smaller nut, a serving size is 42 nuts.
• A serving for macadamia nuts is 18 nuts. 

By Lisa Andrews, MEd, RD, LDReferences:

1. FrancescaPistollato aRuben CalderónIglesiasa RobertoRuiza SilviaAparicioa JorgeCrespoa Luis DzulLopezb Piera PiaManna cFrancescaGiampieric Maurizio Battinoc Nutritional patterns associated with the maintenance of neurocognitive functions and the risk of dementia and Alzheimer’s disease: A focus on human studies. Pharmacological Research Volume 131, May 2018, Pages 32-43. 
2. Sugizaki, C.S.A.; Naves, M.M.V. Potential Prebiotic Properties of Nuts and Edible Seeds and Their Relationship to Obesity. Nutrients2018, 10, 1645.
3. Freisling H, Noh H, Slimani N, et al. Nut intake and 5-year changes in body weight and obesity risk in adults: results from the EPIC-PANACEA study. Eur J Nutr. 2018;57(7):2399-2408. doi:10.1007/s00394-017-1513-0
4. https://www.heart.org/en/healthy-living/healthy-eating/eat-smart/fats/go-nuts-but-just-a-little