Eating too many of some kinds of nuts can introduce nutrients that are toxic in high amounts, according to the National Institutes of Health. Brazil nuts are heart-healthy and help to reduce cholesterol, but they are also high in selenium. If it builds up in the body due to excess consumption, it can lead to neurological disorders, dermatitis, and breakage of hair and nails. At extremely high levels, it can cause death.
Although the fats in nuts provide many of the associated health benefits, they are also high in calories, explains Mayo Clinic. Up to 80 percent of the calories in nuts come from fat. Roasted chestnuts have only 60 calories per 1-ounce serving, but other nuts have over 160 calories per ounce, and macadamia nuts and pecans have over 200 calories per ounce. However, since it is healthy fat, consumers can eat nuts as a substitute for the saturated fats in meats and eggs.
While the excess calories may seem like trouble, studies indicate it is possible to add up to 344 calories daily from almonds and still lose weight, reports Berkeley Wellness. Women who add the almonds lose weight, even if they do not cut back on other calories. Increasing nuts in the diet is a process that should involve time, indicates Harvard Health Publications. Replacing all the protein in the diet with nuts, seeds and grains at once can cause a diet to fail.