Australian dietary guidelines recommend eating 30 grams of nuts every day – a small handful. But many of us know that nuts are high in calories and fat.
Should we eat nuts or are we going to gain weight?
In short, the answer is yes, we should eat them, and no, they will not make us gain weight if they are consumed in moderate amounts. The fats in the nuts are mainly the "good" fats.
And apart from that, our body does not really absorb all the fat found in the nuts. But we absorb the nutrients they provide.
Food fat: friend or foe?
The nuts contain fat, and the amount of fat varies depending on the types of nuts. For example, a 30g serving of cashews or raw pistachios contains about 15g of fat (0.5 ounces), while the same amount of raw macadamias contains about 22g of fat (0.7 ounces).
There are different types of fats in our diet and some are better for us than others. The nuts contain mainly monounsaturated and polyunsaturated fatty acids.
These types of fats are called "good fats". They can help lower cholesterol when we eat them instead of saturated fats.
The type of fat present varies between nuts. For example, nuts are high in polyunsaturated fats, while other types of nuts, such as hazelnuts and macadamias, contain more monounsaturated fats.
What the evidence says
Even though the type of fat in nuts is good for us, they are still rich in fat and calories. But that does not mean we should avoid them to manage our weight.
Studies of dietary habits and body weight over a long period of time have shown that people who consume nuts regularly tend to lose less weight over time than others.
We see a similar trend in clinical studies that asked people to include nuts in their diets and then looked at the effects on body weight.
A review of more than 30 studies examined the effects of nut consumption on body weight. It was not found that people who ate nuts had increased their body weight, body mass index (BMI) or waist circumference, compared to a control group of people not eating nuts.
In fact, one study found that when people ate a type of weight-loss food, the group of people who ate nuts lost more body fat than those who did not eat it.
There are several reasons why nut consumption does not seem to lead to weight gain.
We do not absorb all the fat from the nuts: The fat in the nuts is stored in the cell walls of the nuts, which do not break down easily during digestion. As a result, when we eat nuts, we do not absorb all the fat. Part of the fat is removed in our feces. The amount of calories we eat from eating nuts could be 5 to 30% lower than we thought before.
Nuts increase the amount of calories we burn: Not only do we not absorb all the calories of nuts, but their consumption can also increase the amount of energy and fat that we burn. It is thought that this can partly be explained by the protein and unsaturated fats contained in nuts, although we still do not know exactly how this happens. Increasing the number of calories burned can help us maintain or lose weight.
Nuts help us feel fuller longer: In addition to fat, nuts are rich in protein and fiber. Thus, nuts help us feel full after eating, which means that we will probably eat less at the following meals. Recent studies have also suggested that providing people with nuts helps to improve the overall quality of the types of foods they consume. This may be due to the fact that nuts replace the "malbouffes" in the form of snacks.
People who consume nuts have a healthier lifestyle in general: We can not rule out the idea that eating nuts is simply a sign of a healthier lifestyle. However, randomized controlled trials, which may take into account lifestyle factors such as eating habits, still show no negative effect on body weight when people eat nuts. This means that the beneficial effects of nuts are not only the result of the fact that walnut eaters have a healthier lifestyle: the nuts themselves play a role.
Overall, the evidence suggests that nuts are a healthy snack that can provide us with many of the nutrients our body needs. We can confidently include the recommended 30g of nuts a day in a healthy diet, without worrying about the effect they will have on our waistline.
Elizabeth Neale, Researcher in Career Development (Lecturer), University of Wollongong; Sze-Yen Tan, Lecturer in Nutritional Sciences, Institute of Physical Activity and Nutrition (IPAN), School of Exercise and Nutrition Sciences, Deakin University, and Yasmine Probst , Lecturer, School of Medicine, University of Wollongong.
This article is republished from The Conversation under a Creative Commons license. Read the original article.