For 100 years or so, the caloric value of foods has been calculated using something called the Atwater general factor system. You may not have heard of it by name, but you probably have heard its long-standing pronouncement that proteins and carbohydrates have four calories per gram and fat has nine calories per gram. Of course, many things aren’t as simple as they seem. And it turns out that not all fat is equal when it comes to counting calories.
For details about the study, our editors turned to David Baer, PhD, supervisory research physiologist with the Agricultural Research Service and the study’s lead author, who explained that the purpose of the study was to determine the legitimate calorie value of pistachios in an otherwise balanced diet. He gave us a very “inside” account of their research.
In the study, 16 healthy, nonsmoking men and woman, ages 29 to 64, all without gastrointestinal disorders, ate a consistent balanced diet of typical American food for three weeks. They ate all the food, and only the food, prepared for them by the research center. The participants were weighed each morning and their intake adjusted to keep their weight stable.
While all of this was going on, researchers gave each participant one of three different “doses” of pistachios to eat—0 grams (the control), 42 grams (about one and one-half ounces) and 84 grams (about three ounces) per day—as part of their diet. For the two pistachio diets, which resulted in increased daily intakes of fat and dietary fiber compared with the control, total carbohydrates were reduced—so that total calorie consumption remained at the level where subjects neither gained nor lost weight.
Because the weight, amount of fat and energy (calories) increased in the “end product” when pistachios were added to the diet, researchers concluded that less fat had been digested by the body, which meant that fewer calories than expected had been provided by the pistachios.
In addition, because the researchers found that the amount of dietary fiber consumed increased with the addition of pistachios, the fiber calories of the pistachios were also subtracted from the carbohydrate calorie count, further contributing to a lower calorie count.
In the end, the study found the actual measure of calories for pistachios is about 160 for a typical 30-gram serving (approximately 50 nut meats), instead of the generally accepted 170 calories, making it a nut with one of the lowest calorie counts.
While the study isn’t suggesting that we start to think of pistachios as a diet food, every little bit counts when it comes to calorie counting. Plus, although not planned as part of the study, blood samples analyzed after each protocol found that both amounts of pistachio nuts lowered LDL (bad) cholesterol by 6%.
Next up on the Agricultural Research Service’s nut-calorie-authentication research plan are almonds. We may get more good news.
A FIRST-OF-ITS-KIND STUDY
Recent clinical studies had indicated that the fat in pistachio nuts is not well-absorbed by the body, but there hadn’t been a human study to prove it... until now. The US Department of Agriculture’s Agricultural Research Service recently released the results of a meticulous study tracing the fate of pistachios in the human body. They found that about 6% of their fat calories pass right through us without being absorbed—meaning that pistachios effectively have fewer calories than we had thought.For details about the study, our editors turned to David Baer, PhD, supervisory research physiologist with the Agricultural Research Service and the study’s lead author, who explained that the purpose of the study was to determine the legitimate calorie value of pistachios in an otherwise balanced diet. He gave us a very “inside” account of their research.
In the study, 16 healthy, nonsmoking men and woman, ages 29 to 64, all without gastrointestinal disorders, ate a consistent balanced diet of typical American food for three weeks. They ate all the food, and only the food, prepared for them by the research center. The participants were weighed each morning and their intake adjusted to keep their weight stable.
While all of this was going on, researchers gave each participant one of three different “doses” of pistachios to eat—0 grams (the control), 42 grams (about one and one-half ounces) and 84 grams (about three ounces) per day—as part of their diet. For the two pistachio diets, which resulted in increased daily intakes of fat and dietary fiber compared with the control, total carbohydrates were reduced—so that total calorie consumption remained at the level where subjects neither gained nor lost weight.
CALORIES IN—CALORIES OUT
Everything the participants ate was carefully weighed and chemically analyzed before it went in... and everything was just as carefully analyzed when it came out so that researchers could track the absorption of fat and nutrients in the body. Ingeniously, researchers gave participants a brilliant blue “marker capsule” by mouth to help them identify the beginning and end of the study. Once the blue was out of the body, researchers could be sure there was no more food coming out that should be monitored.Because the weight, amount of fat and energy (calories) increased in the “end product” when pistachios were added to the diet, researchers concluded that less fat had been digested by the body, which meant that fewer calories than expected had been provided by the pistachios.
In addition, because the researchers found that the amount of dietary fiber consumed increased with the addition of pistachios, the fiber calories of the pistachios were also subtracted from the carbohydrate calorie count, further contributing to a lower calorie count.
In the end, the study found the actual measure of calories for pistachios is about 160 for a typical 30-gram serving (approximately 50 nut meats), instead of the generally accepted 170 calories, making it a nut with one of the lowest calorie counts.
While the study isn’t suggesting that we start to think of pistachios as a diet food, every little bit counts when it comes to calorie counting. Plus, although not planned as part of the study, blood samples analyzed after each protocol found that both amounts of pistachio nuts lowered LDL (bad) cholesterol by 6%.
Next up on the Agricultural Research Service’s nut-calorie-authentication research plan are almonds. We may get more good news.
//highenergyforlife.com
