Nuts are a rich source of fat, but many studies have shown that the fat in nuts is absorbed very poorly. Now a study explains why nuts are not fattening (American Journal of Clinical Nutrition, 2015 Jan;101(1):25-33). The fat in almonds is located inside the almond cells. Even after prolonged chewing, most of the almond cells remained intact and the fat was still inside the cells. Since fat is absorbed only after it is released from cells, most of the fat in almonds cannot be absorbed in the upper part of your intestinal tract. This explains why the calorie count of nuts is really lower than what you read on the label.
The calorie counts shown on food labels are computed from how much heat can be produced by the food in a laboratory. However, this method of measuring calories is meaningless for foods that are poorly absorbed. The number of calories listed on the label can be much higher than those a person actually absorbs; many of the potential calories pass through, undigested, in the person's stool. This explains why blood fat levels are lower than expected after a person eats nuts. Another study showed that roasting almonds does not increase the absorption of fat over that absorbed from raw almonds (Br J Nutr, 2014 Nov 14;112(9):1521-9). Some of the fat that has passed through the upper intestines is absorbed after the nuts reach the colon, where bacteria ferment the cell walls to release some of the fat (Am J Clin Nutr, 2004 Sep;80(3):604-13).
Nuts Appear to be Healthful
Epidemiologic studies (on populations) associate eating nuts with reduced likelihood to suffer heart attacks, gallstones, diabetes, and cancer. Many studies show that eating nuts lowers high blood pressure, cholesterol, belly fat, and metabolic syndrome; and that nuts are not associated with gaining weight (Nutrients, 2010 July;2(7):652-82).
This week a study reports that eating almonds reduces belly fat, the type of fat that causes diabetes and heart attacks (Journal of the American Heart Association, published online 1/11/15). Fifty-two middle-aged, apparently healthy but obese adults with high levels of the bad LDL cholesterol were placed on a heart-healthy diet and were fed daily either:
• 1.5 ounces (42 grams) of whole almonds, or
• a banana muffin with the same number of calories as the almonds.
After six weeks, those eating almonds had lower total cholesterol and bad LDL cholesterol levels. Those eating the muffins had their good HDL cholesterols lowered. The almond-eaters also had smaller waist circumferences and less of the belly fat that leads to diabetes. Both groups had the same body weight and total body fat measures.
Why Nuts are More Healthful than Muffins
The almond snack that was given to the study patients contained 30-35 almonds (1.5 ounces), with 240 calories, 20 grams of fat, (primarily monounsaturated) and 4.7 grams of fiber. The muffins contained the same number of calories, but had less fiber, less monounsaturated fat and far more sugar and starch.
A high rise in blood sugar can damage every cell in your body. Muffins are made from flour which causes a much higher rise in blood sugar than whole grains do. Whole grains have a thick capsule that prevents the rapid absorption of sugars and other carbohydrates into your bloodstream. Grains are full of carbohydrates which can be absorbed only as single sugars. When you grind a whole grain into a powder, you remove the capsule around the whole grain and markedly increase the absorption of sugar to cause a high rise in blood sugar. Fat's location inside the cells of nuts reduces absorption of the fat in the same way that the thick outer capsule around whole (unground) grains reduces the absorption of sugar.
What This Means for You
Go ahead and snack on nuts. Try to limit refined carbohydrates made by grinding plants into flour or by adding sugar to any food or drink. This means that you should restrict sugared drinks including fruit juices, and all foods made with any kind of flour: muffins, bread, pasta, pretzels, bagels, crackers, cookies and so forth.