I've been wondering, are nuts really 'fattening'?

Research shows nuts are a rich source of nutrients and cardiovascular health protection, and that eating nuts at least twice a week can put you at a lower risk for weight gain. Scientists from Purdue University did a thorough review of all the studies on nut intake and weight loss. Some of the studies found an inverse relationship between nut intake and body mass index (BMI), others found that increasing nut intake did not cause weight gain.

With the combination of fat and fibre, nuts are an effective appetite suppressant. Nuts can also have poor bioaccessibility, meaning that not all of their calories are absorbed. In a 2010 article published in the "Asia Pacific Journal of Clinical Nutrition," the authors note that your body excretes 10 to 15 percent of the calories in nuts and likely burns an additional 10 percent of the calories through the increased metabolism created by eating nuts. 

While nuts do have a high calorie content, research points to nuts assisting with weight maintenance and loss rather than weight gain. Once people consume nuts, they are likely to consume less of other foods, resulting in a balanced intake of energy. In some cases, eating nuts creates an energy deficit, as dieters who eat nuts tend to lose greater amounts of weight than those who do not, the researchers note.

If you add nuts to your diet without cutting calories elsewhere, weight gain is likely to result, imply the findings of a 2005 study published in the "British Journal of Nutrition." Study subjects were given walnuts to consume in addition to the rest of their diet, with modest weight gain as the end result. However, the weight gain was not nearly as much as expected when the increase in energy intake was considered, suggesting that nuts cause less weight gain per calorie than some other foods.

You can eat nuts without weight gain if you substitute them for other foods in your diet. Substitute them for carbohydrates, as this will promote satiety and weight loss, according to a study published in the February 2003 issue of "The Journal of Nutrition." Measure serving sizes to make sure you aren't consuming more calories than you think. Bear in mind that a 1-oz. serving of cashews is 16 to 18 nuts, a serving of almonds is 20 to 24 nuts and a serving of macadamias is 10 to 12 nuts, according to the University of Michigan Health System.