Eating nuts has numerous health benefits. But you may wonder why roasted peanuts are considered bad for health. Dry roasting the peanuts may result in peanuts losing some nutrients. Usually, nuts are roasted to make them taste, smell, and feel better. When you roast something, you cook it with dry heat, which cooks it evenly on all sides. Most nuts are roasted without their shells, but pistachios are usually roasted with their shells still on. Raw nuts, on the other hand, have not been roasted. 
Sometimes, roasting is used to get the nuts' kernels out of their shells. This is how most cashews are shelled, which is why they're almost never sold raw. There are mainly two ways to roast:
- Dry roasting: Not using any oil to roast. Dry-roasting nuts can be done in the oven or a frying pan.
- Oil roasting: Roasting using oil. Nuts can also be roasted in oil in a pan or oven.
Aside from these two ways, you can also roast nuts in the microwave. You can buy nuts that have already been roasted, or you can do it yourself. When nuts are roasted, their structure and chemical make-up change. In particular, it changes their color and takes away some of their moisture, which makes them crunchy. When nuts are roasted, some of their water is lost. A roasted nut weighs less than a raw nut because of this. So, that explains why roasted nuts have a little more fat per ounce. Some research has shown that roasting nuts don't change how much fat they have overall. But as the structure of the nut changes during roasting, the polyunsaturated fats in the nut become more likely to oxidize. On the other hand, both raw and roasted nuts have about the same amount of protein and carbs. Still, depending on the type of nut, roasted nuts can have slightly more or less of these macronutrients. Contrary to what you might think, oil-roasted nuts are only slightly higher in fat and calories than dry-roasted nuts. That's because nuts already have a lot of fat in them and can't take in much more. 
- Roasting Might Damage the Healthy Fats in Nuts:
The fats in nuts are mostly monounsaturated and polyunsaturated. These good fats can help lower cholesterol in the blood and may help protect against heart disease.
- High Temperatures and Long Cooking Times Have the Greatest Impact:
When polyunsaturated fats are heated, like when you roast something, they are more likely to get damaged or oxidized. This can cause dangerous free radicals to form, which can hurt your cells. Some nuts have an "off" taste and smell because they have oxidized fat, also called rancid fat. You can control the roasting process to reduce the amount of these free radicals that are made. The key is to keep an eye on the time and temperature of cooking. Studies have shown that nuts' fats are less likely to go bad when they are roasted at a low to medium temperature. One study found that the nuts were more likely to have a sign of oxidation if they were roasted at a higher temperature and for a longer amount of time. The type of nut also affected how likely it was to oxidize. For example, when walnuts were roasted at 356°F (180°C) for 20 minutes under very harsh conditions, the substance that showed oxidation went up 17 times compared to when the walnuts were raw. In hazelnuts and pistachios, on the other hand, the substance that showed oxidation only went up by 1.8 and 2.5 times, respectively. The reason for this is that walnuts have a lot of polyunsaturated fat. It makes up 72% of their total fat, making them the nuts with the most fat. In the same study, oxidation was much less when walnuts were roasted at a medium temperature (248–320°F or 120–160°C). 
- Oxidation Can Occur During Storage:
The polyunsaturated fat in nuts is also more likely to turn rancid when they are stored for a long time. This is because when nuts are roasted, their structure changes. This makes it easier for fat to get in touch with oxygen and become oxidized. This makes nuts last less long. Because of this, roasted nuts should be kept for less time than raw nuts. Also, some studies show that trans fats are made when foods are roasted, but the amount is very small.
- Some Nutrients Are Lost During Roasting:
Nuts have a lot of good things for your body, like vitamin E, magnesium, and phosphorus. Also, they have a lot of antioxidants. Some of these nutrients are easily destroyed by heat and may be lost when the food is roasted. For example, when you roast something, some types of antioxidants break down. Antioxidants are good for your health because they help keep free radicals from hurting your cells. Still, it has been shown that higher temperatures and longer roasting times reduce antioxidant activity, but only up to a certain point. In one study, the number of antioxidants in different nuts kept going down from the time they were put in the oven at 302°F (150°C) until 30 minutes later. After 60 minutes, the antioxidant activity went up, which was interesting. When nuts are roasted, a chemical reaction happens that makes compounds with antioxidant properties. Also, roasting doesn't hurt all antioxidants the same way. One study found that roasting nuts did not change the amount of the antioxidants lutein and zeaxanthin in pistachios and hazelnuts. 
Studies have also shown that roasting gets rid of vitamin E, thiamine, and carotenoids. But the amount of loss really depends on the type of nut and how hot it was roasted. In fact, one study showed that more vitamins were lost when almonds and walnuts were roasted than when hazelnuts were roasted, while almost no vitamins were lost when pistachios were roasted. With higher roasting temperatures, more vitamins were lost. The most active form of vitamin E, alpha-tocopherol, also seems to change during roasting. After 25 minutes of roasting at 284°F (140°C), the levels were 20% lower in almonds and 16% lower in hazelnuts than they were in raw nuts. The more alpha-tocopherol was lost, the hotter the food was roasted. 320–340°F (160–170°C) roasting for 15 minutes reduced the levels by 54% in almonds and 20% in hazelnuts compared to raw nuts. Like alpha-tocopherol, thiamine levels went down when the food was roasted, and they went down more at higher temperatures. There was no change in the amount of riboflavin. Overall, roasting affects each type of nut and each nutrient in a different way, depending on the type of nut and how the roasting is done. Even though roasting takes away some vitamins, it's important to remember that nuts are not the main source of these vitamins. Almonds are an exception because they are high in vitamin E.
- Roasting Nuts May Form Harmful Chemicals:
The rich flavor, color, and smell of roasted nuts come from chemical compounds that are made during a process called the Maillard reaction. 
This happens when the amino acid asparagine meets the sugar in the nuts. When nuts are heated above 248°F (120°C), this gives them their brown color. ACRYLAMIDE: The dangerous chemical acrylamide may also be made through the Maillard reaction. Animals who eat a lot of this substance are known to get cancer from it. It might make people more likely to get cancer, but there isn't much proof of that. More acrylamide is made by the temperature of the roasting than by how long it is roasted. Almonds are the ones most likely to make acrylamide because they have a lot of the amino acid asparagine. When almonds are heated above 266°F (130°C), acrylamide starts to form. At temperatures above 295°F (146°C), there are a lot more acrylamides being made. One study showed that the amount of acrylamide in almonds went up a lot when they were roasted for 25 minutes at temperatures between 282 and 323°F. When nuts are roasted, they make different amounts of Acrylamides.
- Different Nuts Produce Different Levels of Acrylamides When Roasted:
In the same study, it was found that when other nuts were roasted, they had less acrylamide. When pistachios were roasted at the same temperature as almonds, the amount of the compound almost doubled. No acrylamide was found in roasted macadamia nuts, walnuts, or hazelnuts. It's important to remember that even though almonds and other foods contain acrylamide, the amounts are much lower than what is thought to be harmful. But if you want to avoid getting too much acrylamide from almonds, you should make sure to roast them at a low temperature, around 265°F (130°C).