Is Frying Food Unhealthy? Cooking Oils, Heat & Health

Frying is not automatically unhealthy, but the type of frying, the food being cooked, the oil used and how often fried foods are eaten all matter. A lightly pan-fried meal prepared with an unsaturated oil is very different nutritionally from regularly eating deep-fried takeaway food.

Why does frying get a bad reputation?

Deep-fried foods can absorb considerable oil, increasing their energy content. Many takeaway fried foods are also high in salt, refined carbohydrate and saturated or trans fats. For that reason, Australian health guidance recommends limiting fried fast foods and choosing healthier cooking methods more often.

Does heating oil make it toxic?

Heating changes cooking oils, particularly when oil is heated for long periods or repeatedly reused. However, this does not mean every vegetable or seed oil becomes “toxic” as soon as it is heated. The type of oil, temperature, cooking time and repeated use all influence how an oil behaves.

Which oils are better choices?

For everyday cooking, oils rich in unsaturated fats are generally preferred over fats high in saturated fat. Extra virgin olive oil and canola oil are practical choices. Other plant oils can also fit into a healthy diet.

The bigger nutritional priority is replacing saturated fats such as butter, coconut oil, palm oil and animal fats with mono- and polyunsaturated fats where practical.

What about smoke point?

Smoke point is useful, but it is not the only measure of whether an oil is suitable for cooking. Stability, fatty-acid composition, antioxidants, temperature and duration of heating also matter. Avoid deliberately overheating oil until it smokes heavily.

Deep frying versus pan frying

Deep frying generally uses more oil and can substantially increase the energy density of food. Pan frying or sautéing with a modest amount of unsaturated oil can be a more practical everyday option. Baking, grilling, steaming and air frying can reduce the amount of added fat further.

Should cooking oil be reused?

Repeated heating can degrade oil. At home, it is sensible to avoid repeatedly reheating the same oil, especially if it has darkened, developed an unusual smell, become thick or has been overheated.

A healthier approach to fried food

Think about the whole meal rather than fearing a single cooking technique. Use an appropriate unsaturated oil, avoid excessive heat, limit deep-fried takeaway meals, and make vegetables, whole grains, legumes, fish and other minimally processed foods the foundation of your diet.

Frequently asked questions

Is olive oil safe for cooking?

Yes. Olive oil is suitable for many common cooking methods and is a source of monounsaturated fat.

Are seed oils unhealthy?

Current mainstream nutrition evidence does not support avoiding all seed oils. Unsaturated plant oils can be useful replacements for saturated fats.

Is air frying healthier than deep frying?

Air frying generally requires much less added oil than deep frying, so it can reduce the amount of fat and energy added during cooking.

About Mick Jordan

Mick Jordan is a naturopath and Sports and Remedial Massage Therapist based in Brighton, Melbourne, with more than 30 years’ experience in natural therapies. He has a particular interest in nutrition, digestive health, sports performance and recovery, and takes an individual approach to helping clients improve their health and wellbeing.

This article is general nutrition information and does not replace personalised medical or dietary advice.