Nuts are extremely healthy because they are rich in nutrients and antioxidants (1).
Indeed, they are linked to a wide range of health benefits, including protection against heart disease and diabetes (2).
However, they are also high in fat and calories, which means that many people avoid hazelnuts for fear of gaining weight.
This article reviews the tests to determine if the nuts are good for weight loss or fattening.
Nuts are high in fat and calories
Nuts are high in calories.
Indeed, most of them are fats, which are a concentrated source of energy. One gram of fat contains 9 calories, while one gram of carbohydrates or protein contains only 4 calories.
Nuts mainly contain unsaturated fats. This type of fat is associated with protection against many different diseases, such as heart disease (3).
Below are the calories and fat content per one ounce (28 grams) serving of some commonly consumed nuts:
Nuts: 183 calories and 18 grams of fat (4)
Brazil nuts: 184 calories and 19 grams of fat (5)
Almonds: 161 calories and 14 grams of fat (6)
Pistachios: 156 calories and 12 grams of fat (7)
Cashew: 155 calories and 12 grams of fat (8)
Because they are high in fat and calories, many people believe that adding nuts to their diet will lead to weight gain.
However, as noted below, scientific studies do not support it.
Summary: Nuts are high in calories because they are high in fat, a concentrated source of energy. Even small portions are high in fat and calories.
Eating nuts regularly is not linked to weight gain
Several observational studies have shown that regular consumption of nuts is not associated with weight gain and may even prevent it (9, 10, 11, 12, 13).
For example, one study looked at the diets of 8,865 men and women for 28 months.
It has been found that those who ate two or more servings of nuts per week had a 31% lower risk of gaining weight than those who never or rarely ate them (10).
In addition, a review of 36 studies found that regular consumption of nuts was not related to weight gain, body mass index (BMI) or size of life (14).
In controlled studies where participants had to adhere to a strict diet, adding many types of nuts did not cause changes in body weight (15, 16).
More importantly, in studies where nuts have been added to the diet of people who have been able to eat as they wish, consumption of nuts has not resulted in weight gain (17, 18).
That said, a small number of studies have reported that eating nuts is associated with increased body weight (19, 20).
However, any weight gain was very small, much lower than expected and tended to be insignificant in the long run.
Summary: Studies have shown that eating nuts on a regular basis does not promote weight gain, that people are following a strict diet or eating as they please. In some cases, they protect against weight gain.
Eating nuts can also increase weight loss
Many large observational studies have shown that more frequent consumption of nuts is associated with lower body weight (12, 13, 21, 22).
It’s unclear why this is, but it may be partly due to the healthier lifestyle choices of those who eat nuts.
However, human studies show that including nuts as part of a weight loss diet does not interfere with weight loss. In fact, weight loss often increases (23, 24, 25, 26, 27).
For example, a study of 65 overweight or obese subjects compared a low-calorie diet supplemented with almonds to a low-calorie diet supplemented with complex carbohydrates.
They consumed equal amounts of calories, protein, cholesterol and saturated fat.
By the end of the 24-week period, people on an almond diet had a 62% reduction in weight and BMI, 50% in waist circumference and 56% in body fat (23) .
In other studies, low-calorie diets containing nuts have resulted in weight loss similar to a controlled low-calorie diet.
However, the group that consumes nuts has seen improvements in cholesterol, including a reduction in “bad” LDL cholesterol and triglycerides. This benefit has not been felt by those who consume nut-free diets (26, 27).
Summary: Eating nuts regularly as part of a diet can increase weight loss and improve cholesterol.
Nuts can help reduce appetite and increase feelings of fullness
Adding nuts to the diet has been linked to reduced hunger and feeling fuller for longer (28, 29).
For example, almond snacks have been shown to reduce hunger and appetite (28).
In one study, more than 200 people were asked to eat a serving of peanuts as a snack.
As a result, they naturally ate fewer calories later in the day. This effect was greater when peanuts were eaten as a snack rather than a main meal (30).
Their appetite suppressing effects are thought to be likely due to the increased production of peptide hormones YY (PYY) and / or cholecystokinin (CCK), both of which help regulate appetite (31).
The theory is that a high level of protein and unsaturated fat may be responsible for this effect (31, 32).
Studies suggest that 54 to 104% of the additional calories from adding nuts to the diet are canceled out by a natural reduction in the consumption of other foods (18, 19).
In other words, eating nuts as a snack increases the feeling of fullness, which results in less consumption of other foods (33).
Summary: the consumption of nuts is associated with a decrease in appetite and a greater feeling of satiety. This means that people who eat them can naturally eat less during the day.
Only part of the fat is absorbed during digestion
The structure and high fiber content of nuts means that unless they are crushed or chewed completely, a good proportion will pass through the undigested intestine.
Instead, it is emptied into the intestines. As a result, certain nutrients, such as fat, will not be absorbed and will instead be lost in the stool.
This is another reason why nuts seem to be friendly for weight loss.
In fact, studies have found that after eating nuts, the amount of fat lost through the stool has increased from 5% to over 20% (33, 34, 35, 36).
This suggests that much of the fat in nuts is not even absorbed by your body.
Interestingly, the way nuts are processed can have a big effect on how nutrients like fat are absorbed.
For example, one study found that the amount of fat excreted in the stool was higher for whole peanuts (17.8%) than for peanut butter (7%) or peanut oil (4.5 %). (35).
Roasted nuts can also increase the absorption of their nutrients (37).
Therefore, the absorption of fats and calories from nuts is probably the minimum when you eat them whole.
Summary: part of the fat contained in nuts is not well absorbed and is rather removed from the stool. Fat loss is likely to be greatest after consuming whole nuts.
Nuts Can Increase Fat and Calorie Consumption
Some evidence suggests that eating nuts can increase the number of calories burned at rest (17, 18).
One study found that participants burned 28% more calories after a meal containing nuts than a meal containing dairy fat (38).
Another study found that supplementing peanut oil for eight weeks resulted in a 5% increase in calorie consumption. However, this has only been observed in overweight people (39).
In addition, some studies show that in overweight and obese people, eating nuts can increase fat burning (40).
However, the results are mixed and better studies are needed to confirm the link between nuts and increased calorie consumption.
Summary: Several studies suggest that the consumption of nuts can increase the consumption of fats and calories in overweight or obese people.
Although they are high in fat and calories, nuts are incredibly healthy.
Eating nuts regularly as part of a healthy diet is not associated with weight gain and can also help you lose weight.
However, it is important to exercise control over the portions. Public health guidelines recommend eating a 28-gram serving of nuts most days of the week.
For the healthiest option, choose simple, unsalted varieties.
More information on nuts and weight loss:
- Top 9 nuts to eat for better health
- 8 health benefits of nuts
- The 20 slimmest foods on the planet