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Dean Pomerleau posted a topic in CR PracticeMany CR practitioners, including me, consume a lot of nuts, for their benefits to health (e.g. reduced CVD) and mortality. And it is been pretty common knowledge among those who follow this stuff closely, that it is surprisingly hard to get fat eating nuts. In fact, several years ago, Dr. Greger had did a 7-part video series (beginning here) seeking to explain the missing calories in nuts by looking at all the various theories. I highly recommend watching for those who haven't. Now, it finally looks like the USDA is waking up to the issue of missing calories in nuts, specifically walnuts. In this new study , discussed here, researchers at the FDA tracked 18 people in very controlled conditions on a diet lacking or supplemented with walnuts. They took samples of what they ate, and what they excreted, and determined that walnuts, "consistent with other tree nuts", contained 21% fewer available calories than predicted by the Atwater method typically used to compute calorie content of foods, basically a sophisticated version of the 9-4-4 Fat-Carb-Protein method for estimating calories. They found walnuts contained 5.22 kcal/g, rather than 6.61 kcal/g as predicted by Atwater. They said their finding could result in changes to food labelling practices. And as the authors indicate, this lower calorie content than predicted is almost certainly true of other nuts as well. No word on seeds though... As of now, the USDA food database, and hence CRON-O-Meter and other diet tracking tools, still used 6.61 kcal/g (actually I just checked, CRON-O-Meter uses 6.54 kcal/g) rather than the lower, more realistic, 5.22 kcal/g. --Dean -----------  J Nutr. 2015 Nov 18. pii: jn217372. [Epub ahead of print] Walnuts Consumed by Healthy Adults Provide Less Available Energy than Predicted by the Atwater Factors. Baer DJ(1), Gebauer SK(2), Novotny JA(2). Author information: (1)USDA, Agricultural Research Service, Beltsville Human Nutrition Research Center, Beltsville, MD David.Baer@ars.usda.gov. (2)USDA, Agricultural Research Service, Beltsville Human Nutrition Research Center, Beltsville, MD. BACKGROUND: Previous studies have shown that the metabolizable energy (ME) content (energy available to the body) of certain nuts is less than predicted by the Atwater factors. However, very few nuts have been investigated to date, and no information is available regarding the ME of walnuts. OBJECTIVE: A study was conducted to determine the ME of walnuts when consumed as part of a typical American diet. METHODS: Healthy adults (n = 18; mean age = 53.1 y; body mass index = 28.8 kg/m(2)) participated in a randomized crossover study with 2 treatment periods (3 wk each). The study was a fully controlled dietary feeding intervention in which the same base diet was consumed during each treatment period; the base diet was unsupplemented during one feeding period and supplemented with 42 g walnuts/d during the other feeding period. Base diet foods were reduced in equal proportions during the walnut period to achieve isocaloric food intake during the 2 periods. After a 9 d diet acclimation period, subjects collected all urine and feces for ∼1 wk (as marked by a Brilliant Blue fecal collection marker) for analysis of energy content. Administered diets, walnuts, and fecal and urine samples were subjected to bomb calorimetry, and the resulting data were used to calculate the ME of the walnuts. RESULTS: One 28-g serving of walnuts contained 146 kcal (5.22 kcal/g), 39 kcal/serving less than the calculated value of 185 kcal/serving (6.61 kcal/g). The ME of the walnuts was 21% less than that predicted by the Atwater factors (P < 0.0001). CONCLUSION: Consistent with other tree nuts, Atwater factors overestimate the metabolizable energy value of walnuts. These results could help explain the observations that consumers of nuts do not gain excessive weight and could improve the accuracy of food labeling. This trial was registered at clinicaltrials.gov as NCT01832909. © 2016 American Society for Nutrition. PMID: 26581681