Dietitian Melanie Thomassian at her Dietriffic blog April 27, 2010, notes that nuts are not fattening, contrary to popular belief. This is in a guest post by Matthew Denos. Most of his references refer to almonds, so I’m not sure other nuts would be equally non-fattening.
We’re talking about one or two ounces (up to 60 grams) a day. Could someone gain fat weight eating more than that? Probably, especially if they have a high-carbohydrate eating pattern. Do I have scientific studies to back me up? No.
Nuts are characteristic of the traditional Mediterranean diet, which is one reason I included them in the Ketogenic Mediterranean Diet. The other reason is that nut consumption is associated with lower heart disease risk.
Diabetic Mediterranean Diet 