In the study’s discussion section, the authors considered the potential implications of substituting other foods with almonds in a calorie-controlled study. Based on the data, “When an 84-g serving of almonds was incorporated into the diet daily, the energy digestibility of the diet as a whole decreased by 5%. Therefore, for individuals with energy intakes between 2000 and 3000 kcal/d, incorporation of 84 g almonds into the diet daily in exchange for [the same number of calories from] highly digestible foods would result in a reduction of available energy of 100–150 kcal/d. With a weight-reduction diet, this deficit could result in more than a pound of weight loss per month.”ⁱ

The new study’s results support previous research indicating that the fat in almonds is not absorbed as easily as the fat in most other foods, due to almonds’ cellular structure.  This implies that traditional methods of calculating calories overstate those calories coming from almonds because they do not account for the fact that fat digestibility from nuts is less than that from other foods.

In fact, the same research team also recently conducted a similar study using pistachios, finding a 5% decrease in pistachios’ calorie count compared to the 20% decrease in almonds'.^{iii  i}

Most often, foods’ calorie counts are calculated based on a system developed by Atwater et. al.  more than 100 years ago. Known as the Atwater general factors, the system assigns calorie values for every gram of protein, fat and carbohydrate found in a given food (4 kcal/g for protein, 9 kcal/g for fat and 4 kcal/g for carbohydrate).

As the new study notes, however, “There have been few, if any, studies that looked at the calorie value of whole food within a mixed diet that could confirm … Atwater’s coefficients.”

So, for this study, the researchers expanded on Atwater’s approach, using a specially designed diet and new method of calculation that allowed them to extrapolate the calories from almonds eaten as part of a full diet.

“This new information indicates we get fewer calories than we thought from a handful of almonds,” says Karen Lapsley, DSc, chief science officer for the Almond Board of California based in Modesto. “Considering the 100-plus-year history of traditional methods of nutritional analysis, this is really starting to get interesting.”

The study notes that its results are applicable only to whole almonds, and while no additional studies have been conducted yet, the discrepancy in calories might not be consistent for other forms of almonds such as almond butter or slivered or sliced almonds, as the finer particles might lead to more complete digestion. Globally, however, whole almonds are consumed in far greater proportion than are other forms.

The California almond industry is now working with government agencies to determine what these study results might mean for future consumer education about almonds, such as Nutrition Facts panels.

Almonds are nutrient rich. Ounce for ounce, they contain more protein (6 g), dietary fiber (3.5 g), calcium (75 g), vitamin E (7.4 mg), riboflavin (0.3 mg) and niacin (1 mg) than any other tree nut. Almonds are also heart smart. Scientific evidence suggests, but does not prove, that eating 1.5 ounces per day of most nuts, such as almonds, as part of a diet low in saturated fat and cholesterol might reduce the risk of heart disease. A 1-ounce handful contains 13 grams of unsaturated fat, only 1 gram of saturated fat and no cholesterol.

The Study
A study was conducted to determine the energy value of almonds in the human diet and to compare the measured energy value with the value calculated from Atwater factors, the primary method used to determine the energy content of foods. To calculate the measured energy value of almonds, 18 healthy adults consumed one of three diets for 18 days each. The three treatments were administered to subjects in a crossover design where the diets contained one of three almond doses: 0, 42 or 84 grams per day. During the final nine days of each treatment, volunteers collected all urine and feces, and samples of diets, urine and feces were analyzed for macronutrient and energy contents. From this, the “measured” (metabolizable) energy content of the almonds was determined.

Results: The energy content of almonds in the human diet was measured at 129 kilocalories per 28-gram (or 1-ounce) serving (4.6 +/- 0.8 kcal/g). This is significantly less than the calculated energy content of 168 to 170 kcal per serving (6.0 to 6.1 kcal/g) for the almonds used in this study as determined by the Atwater factors. When applied to almonds, the Atwater factors resulted in a calculated value that was 20% greater than the measured energy value.

Conclusion: This study offers evidence that almonds provide approximately 20% fewer metabolizable calories than originally thought. The Atwater factors, when applied to certain foods, might result in overestimation of their measured metabolizable energy content. Traditional methods overstated the calories from almonds because they do not account for the fat that is not fully absorbed. This is thought to be due in part to the fiber content and/or the rigidity of almond cell walls.

Consumers all over the world enjoy California Almonds as a natural, wholesome and quality food product, making almonds California’s leading agricultural export in terms of value. The Almond Board of California promotes almonds through its research-based approach to all aspects of marketing, farming and production on behalf of the more than 6,000 California almond growers and processors, many of whom are multi-generational family operations. Established in 1950, the Almond Board of California is a nonprofit organization that administers a grower-enacted Federal Marketing Order under the supervision of the USDA.

For more information on the Almond Board of California or almonds, visit www.AlmondBoard.com.

ⁱNovotny JA, Gebauer SK, Baer DJ. Discrepancy between the Atwater factor predicted and empirically measured energy values of almonds in human diets.  American Journal of Clinical Nutrition. 2012 ajcn.035782; First published online July 3, 2012.doi:10.3945/ajcn.112.035782

ⁱⁱEllis PR, et. al. Role of cell walls in the bioaccessibility of lipids in almond seeds. Am J Clin Nutr 2004; 80:604-13.

ⁱⁱⁱBaer DJ, Gebauer SK, Novotny JA. Measured energy value of pistachios in the human diet.British Journal of Nutrition 14 January 2012 107 : pp 120-125

^ivAtwater, WO, Bryant AP. The availability and fuel value of food materials. Storrs, CT: USDA, 1900 (Agriculture Experiment Station 12th Annual Report 73-110.)

U.S. Department of Agriculture, Agricultural Research Service. 2011. USDA National Nutrient Database for Standard Reference, Release 24. Nutrient Data Laboratory Home Page, http://www.ars.usda.gov/ba/bhnrc/ndl