A recent analysis of 86 studies found that “there is no association between nuts and weight gain, and in fact some analyses showed higher nut intake associated with reductions in body weight and waist circumference (Obesity Reviews, Sept 28, 2021). The researchers from University of Toronto noted that even though nuts are concentrated sources of fats, “The physical structure of nuts may also contribute to fat malabsorption due to the fat content in nuts being contained within walled cellular structures that are incompletely masticated or digested.”
Many other studies show that eating tree nuts or peanuts with a high-fat or high-sugar meal prevents the expected high rise in blood factors that increase risk for the inflammation that can lead to diabetes, heart attacks or strokes.
• Three ounces of ground peanuts that contain 198 kcal taken with a high-fat meal prevented the expected constriction of arm arteries and blocked the expected high rise in blood triglycerides (J Nutr, May 2017;147(5):835-840).
• Adding peanuts to a meal delayed the expected high rise in lipopolysaccharides (a measure of triglycerides) and caused insulin levels to return to normal faster (J Hum Nutr Diet, Feb 2016;29(1):95-104).
• 51 men and women, ages 21–73, with high average LDL cholesterol levels of 159 mg/dL (normal is below 100) took 28 to 64 grams of cashews/day for 28 days and had a significant lowering of their high total and bad LDL cholesterols (American Journal of Clinical Nutrition, March 30, 2017).
• 86 healthy overweight adults went on a calorie-restricted diet plus 1.5 ounces of almonds (250 calories) or 250 calories of muffins for six weeks. Those taking the almonds lowered their belly fat and blood pressure more than those taking the muffins (The Journal of Nutrition, December 1, 2016;146(12):2513-2519), possibly because the fat in nuts is poorly absorbed; see Why Nuts Won’t Make You Fat. When 48 people with high LDL cholesterol followed the same program, those eating the almonds had lower total cholesterol, LDL cholesterol, belly fat and leg fat compared to the muffin-snack group (J Am Heart Assoc, Jan 2015; 4(1): e000993).
• A review of 61 studies showed that nuts lower total cholesterol, the bad LDL cholesterol, ApoB and triglycerides (Am J Clin Nutr, Dec 2015;102(6):1347-56). It made little difference what type of nuts were studied.
Nuts Reduce Inflammation
Harvard researchers followed more than 5000 people and found that those who ate five or more servings of nuts per week had much lower markers of inflammation: a 20 percent lower level of C-reactive protein (CRP) and a 16 percent lower interleukin 6 (IL6) than those who rarely ate nuts (Am J Clin Nutr, September 2016;104(3):722-728). One serving of nuts was defined as one ounce of peanuts or tree nuts, or one tablespoon of peanut butter. The apparent benefits of nuts were similar regardless of the type of nuts people ate, though there was no benefit seen for peanut butter. Those who substituted three servings per week of nuts in place of red meat, processed meat, eggs, or refined grains had significantly lower levels of CRP and IL6. Peanuts and tree nuts contain many important nutrients such as magnesium, fiber, L-arginine, antioxidants, and unsaturated fatty acids such as a-linolenic acid. Researchers in this study received funding from the Tree Nut Council and the Peanut Institute.
More Favorable Studies on Nuts
• A review of 14 studies showed that people who eat nuts five times a week have a significantly lower rate of heart disease (Coron Artery Dis, May 2016;27(3):227-32).
• Another review of the world’s literature showed that higher nut consumption is associated with reduced risk of heart attacks, death from heart attacks and death from all causes (Br J Nutr, 2016 Jan 28;115(2):212-25).
• Of 20,742 male physicians followed for 10 years, those who took in the most nuts had the lowest rate of deaths from all causes and deaths from heart disease (Am J Clin Nutr, February 2015;101(2):407-412).
• Eating nuts is associated with reduced death rate from heart attacks and all causes in many different ethnic groups including African Americans, poorer European-descent Americans, and Chinese living in Shanghai, China (JAMA Intern Med, May, 2015;175(5):755-66).
Nuts Are Not “Fattening”
Nuts are a rich source of fat, but many studies show that the fat in nuts is absorbed very poorly and therefore is not a major cause of weight gain (American Journal of Clinical Nutrition, Jan 2015;101(1):25-33). The fat in nuts is located inside the cells, so even after prolonged chewing, most of the 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 nuts 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.
• People who eat nuts frequently are at reduced risk for obesity, diabetes, heart attacks and sudden death.
• Nut eaters may be protected because nuts help to lower markers of inflammation, blood pressure and cholesterol.
• Nuts are not associated with weight gain, even though they are full of fat.
• I now eat mostly unsalted nuts, based on studies such as the one cited in my report on How Excess Salt Affects You. However, this research has shown that you have to take in a lot of salt to be harmed by it. Enjoy the types of nuts that taste best to you.