Is Air Frying Healthier?

Air fryers are all the rage, and as a Registered Dietitian, I’ve heard patients express their love of their air fryer on a regular basis for years. But then the question follows, ‘is air frying healthier?’ In this post, we are going to explore what research has found concerning just that. The assumption has been that because you are using less oil when using air frying as an alternative to deep frying, that there would be less fat and oxidation by comparison. Let’s dig in and see what is actually happening.

What is Oxidized Fat?

When we cook, fat in the foods we are cooking oxidize as they react with oxygen in the air, leading to chemical changes that can produce potentially harmful compounds that contribute to inflammation. Cooking oils, composed of fats, can undergo oxidation during cooking due to exposure to air, heat, and light.

The oxidation process varies to some degree with different cooking methods.

Frying, with its high temperatures, accelerates fat oxidation and the formation of harmful compounds such as free radicals, lipid peroxides, and trans fats, degrading the oil’s quality. If the oils is reused multiple times, it just gets worse.

Roasting typically involves cooking food in an oven at high temperatures, often with a coating of oil. While the exposure to air is less direct compared to frying, the extended cooking time and high temperatures can still lead to some degree of fat oxidation. The oil coating can act as a barrier, but it doesn’t completely prevent oxidation, especially if the oil is of low quality or the cooking time is excessive.

Sautéing involves cooking food quickly in a smaller amount of oil over medium to high heat, which can still promote some level of fat oxidation.

⭐️ A trick I like to use is choosing oils less prone to oxidation and sauteing with a bit of broth to add in saucey moisture without continually adding more fat to make food moist (I’m sorry if the word moist offends you😆).

Grilling involves cooking food over an open flame or heat source. While grilling doesn’t directly involve cooking in oil, the fat present in the food can drip onto the hot coals or grill grates, leading to smoke and flare-ups. These conditions can promote the production of potentially harmful compounds through fat oxidation and combustion, as well as smoke’s own potentially harmful compounds.

⭐️ Marinating your foods prior to grilling can go a long way in decreasing these effects (and make food much tastier).

So, the ranking from most to least oxidation would be: Frying > Roasting > Grilling > Sautéing.

Choosing oils with higher smoke points and avoiding overheating can help minimize fat oxidation during cooking. For more information about oils and their smoke points, read the post ‘Choosing the Best Cooking Oil: Anti-Inflammatory Diet Essentials‘.

Is air frying healthier than deep frying?

‘But wait, you skipped air frying’ you say? In contrast to frying, air frying requires only a thin coating of oil or possibly no oil at all. While some fat oxidation can still occur due to exposure to the increased air circulation and high heat in air frying, it’s generally much less compared to deep frying because of the reduced oil usage. If you would not usually use fat on the food, then there may not be a benefit to air frying instead of baking.

Research comparing air frying to frying has shown that there are less acrylamides and oxidized cholesterol products in air fried food. So yes, air frying will lessen the formation of undesirable products that occur when we cook with fat.

Air Frying May Be Better Than Steaming or Sauteing, Not Just Deep Frying?!

I was really surprised to see a study in a journal called Antioxidants which found air frying to surpass freeze drying, sauteing, and even steaming in preserving the phenolic compounds in five Brassica vegetables, including red cabbage, green cabbage, broccoli sprouts, Brussels sprouts, and kale.

Real quick, WTF are phenolic compounds again???

Phenolic compounds are a diverse group of organic compounds characterized by the presence of one or more phenol (hydroxybenzene) functional groups. These compounds are ubiquitous in nature and can be found in plants, microorganisms, and some animals. They play various roles in biological systems and have diverse chemical structures.

Some common types of phenolic compounds include:

  1. Phenolic acids: These compounds contain a phenol ring with one or more carboxylic acid groups attached. Examples include gallic acid, ferulic acid, and caffeic acid.
  2. Flavonoids: Flavonoids are a large class of phenolic compounds found in fruits, vegetables, and other plant-based foods. They often contribute to the color of plants and have antioxidant properties. Examples include quercetin, kaempferol, and catechins.
  3. Lignans: Lignans are phenolic compounds found in plants, particularly in seeds, grains, and fiber-rich foods. They have been studied for their potential health benefits, including antioxidant and estrogenic effects.
  4. Stilbenes: Stilbenes are a group of phenolic compounds characterized by a central styrene double bond with two phenol rings. Resveratrol, found in red wine and grapes, is a well-known stilbene with antioxidant properties.
  5. Tannins: Tannins are polyphenolic compounds found in many plant tissues, such as bark, leaves, and fruit skins. They are known for their ability to bind and precipitate proteins, giving astringent properties. Tannins can be divided into two main groups: hydrolyzable tannins and condensed tannins (also called proanthocyanidins).

Phenolic compounds have attracted significant attention due to their potential health benefits, including antioxidant, anti-inflammatory, anticancer, and cardioprotective properties. They are also of interest in various industries, such as food, pharmaceuticals, and cosmetics, for their antioxidant and preservative properties.

Okay, now that we appreciate what phenolic compounds are and why we care about them being retained in the food we eat, let’s get back to our study comparing cooking methods including air-frying… The bar graph below shows quite a dramatic difference among cooking methods in preserving phenolic compounds, actually:

AF = Air Frying, FD = Freeze Drying, Steam is the darker shade of ‘c’, Saute is the lighter shade of ‘c’… why on Earth would they not call it ‘d’ idk. The vertical axis is the concentration of phenolic compounds still present in the brassica vegetables after the cooking method.

How does air frying surpass sauteing, steaming, and freeze drying in preserving phenolic content so dramatically? Authors of the study speculate that there may be a leaching of the nutrients and phenolic compounds during the sauteing and steaming process, regardless of the types of vegetables. The loss of nutrients with freeze drying is a contrast to findings of other studies, However, FD is beating out sauteing and steaming here. Pretty good news for astronauts, hikers, and toddlers everywhere.

Total Antioxidant Capacity

Antioxidant activity differences among cooking methods shocked me. Again, air frying retains such a higher amount of antioxidant activity compared to sauteing and steaming. And again, the authors attribute this to leaching into cooking oil or liquid.

The effects cooking techniques on total flavonoid antioxidant content of the tested Brassica vegetables.

Air Frying vs Convection Baking

While I never bought an air fryer, when we needed a new stove/oven, the ones with an air fryer setting were appealing. Ultimately we did buy a new oven with this option.

Air Fry and Convection Bake Setting Options…which to choose?

Both air frying and convection baking utilize a fan to circulate hot air around the food for even cooking, but they have different purposes and cooking techniques:

  1. Air Fry: This setting is specifically designed to mimic the results of deep frying using hot air and a small amount of oil or sometimes no oil at all. It’s great for achieving crispy textures on foods like fries, chicken wings, or breaded items. Use the air fry setting when you want to crisp up foods quickly without deep frying them in oil.
  2. Convection Bake: This setting is more akin to traditional baking but with the added benefit of the convection fan for even heat distribution. It’s suitable for baking cookies, cakes, roasting vegetables, or cooking meats. Convection baking is ideal for recipes that require gentle, even heat and where you want to achieve a tender texture rather than a crispy one.

Here’s a simple guideline:

  • Use the Air Fry setting for foods you want to crisp up quickly, like fries, chicken nuggets, or breaded items.
  • Use the Convection Bake setting for foods that require gentle, even cooking, like baked goods, roasts, or casseroles.

Ultimately, it depends on the specific recipe and the texture you’re aiming for. You may need to experiment a bit to see which setting works best for your desired outcome.

Air Frying and Weight Loss

Air fryers have offered an alternative to the ever popular fried foods, offering a healthier alternative that aligns well with weight loss goals. This innovative cooking method drastically reduces the need for oil. By using an air fryer, we can achieve that coveted crispy texture without the added calories and inflammatory compounds that come from deep frying. Foods cooked in air fryers can retain their flavor and crispiness while having a lower fat content.

This significant reduction in oil absorption not only contributes to a lower calorie intake but also supports a healthier eating pattern. For those of us looking to shed some pounds, incorporating an air fryer into our kitchen arsenals seems like a smart move. It allows us to enjoy our favorite fried foods – from French fries to chicken – without derailing our weight loss goals. Hence, air frying enables us to strike a delightful balance between indulging responsibly and adhering to a health-conscious diet.

Is air frying healthier? Evidence suggests, yes. Compared to frying it is for sure. But it may help preserve beneficial plant compounds compared to other cooking methods, as well. Do you have an air fryer? If you do, what do you like to use it for? Share in the comments below!

References:

Ferreira FS, Sampaio GR, Keller LM, Sawaya ACHF, Chávez DWH, Torres EAFS, Saldanha T. Impact of Air Frying on Cholesterol and Fatty Acids Oxidation in Sardines: Protective Effects of Aromatic Herbs. J Food Sci. 2017 Dec;82(12):2823-2831. doi: 10.1111/1750-3841.13967. Epub 2017 Nov 10. PMID: 29125626.

Sansano M, Juan-Borrás M, Escriche I, Andrés A, Heredia A. Effect of pretreatments and air-frying, a novel technology, on acrylamide generation in fried potatoes. J Food Sci. 2015 May;80(5):T1120-8. doi: 10.1111/1750-3841.12843. Epub 2015 Apr 13. PMID: 25872656.

Wang Y, Wu X, McClements DJ, Chen L, Miao M, Jin Z. Effect of New Frying Technology on Starchy Food Quality. Foods. 2021 Aug 11;10(8):1852. doi: 10.3390/foods10081852. PMID: 34441629; PMCID: PMC8393420.

Grootveld M. Evidence-Based Challenges to the Continued Recommendation and Use of Peroxidatively-Susceptible Polyunsaturated Fatty Acid-Rich Culinary Oils for High-Temperature Frying Practises: Experimental Revelations Focused on Toxic Aldehydic Lipid Oxidation Products. Front Nutr. 2022 Jan 5;8:711640. doi: 10.3389/fnut.2021.711640. PMID: 35071288; PMCID: PMC8769064.

Nandasiri R, Semenko B, Wijekoon C, Suh M. Air-Frying Is a Better Thermal Processing Choice for Improving Antioxidant Properties of Brassica Vegetables. Antioxidants (Basel). 2023 Feb 15;12(2):490. doi: 10.3390/antiox12020490. PMID: 36830048; PMCID: PMC9952021.

Lee JS, Han JW, Jung M, Lee KW, Chung MS. Effects of Thawing and Frying Methods on the Formation of Acrylamide and Polycyclic Aromatic Hydrocarbons in Chicken Meat. Foods. 2020 May 4;9(5):573. doi: 10.3390/foods9050573. PMID: 32375322; PMCID: PMC7278627.

Navruz-Varlı S, Mortaş H. Acrylamide formation in air-fried versus deep and oven-fried potatoes. Front Nutr. 2024 Jan 11;10:1297069. doi: 10.3389/fnut.2023.1297069. PMID: 38274202; PMCID: PMC10808661.

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Anne Marie Berggren RDN, MS, CDN, CNSC is a Registered Dietitian with a Master's Degree in Nutrition, training in integrative and functional nutrition, nutrition for mental health, obesity and weight management, is a board certified nutrition support clinician, and an adjunct professor for the Stony Brook Graduate Nutrition Program teaching advanced clinical nutrition.

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