Walk past any street-side pakora stall in the evening and look at the oil in the kadai. By six o’clock it is often the colour of strong tea, thick and smoking, having fried batch after batch since morning. Most of us sense that oil is not doing anyone any favours. What fewer people realise is that a gentler version of the same chemistry plays out in our own kitchens, in the frying oil we strain and reuse, and in the refined oils we buy because they look so clean and pure.
Cooking fat is a daily, unavoidable part of Indian food, so this is worth understanding properly. The quality of the oil, and even more the way it is handled, has a real bearing on something called oxidative stress, which sits underneath a surprising amount of long-term disease. Let us take it step by step.
What does refined actually mean?
A refined oil has been through an industrial cleanup: high heat, chemical solvents, bleaching and deodorising, all to produce the pale, odourless, long-lasting liquid on the supermarket shelf. The process removes impurities, but it also strips away much of the oil’s natural protection, including vitamin E and other antioxidant compounds that guard the oil, and later your body, against damage. Think of the difference between whole wheat atta and maida. Refining makes things whiter, smoother and more convenient, and quietly removes the part that was protecting you.
What happens when oil is heated, and heated again
Oxidation is the same chemistry that rusts iron and browns a cut apple: oxygen attacking a material and changing its structure. Oils oxidise too, and heat speeds this up enormously. Every time an oil is taken to a high temperature, some of its fat molecules break down into oxidised lipids and other reactive fragments. Reusing the oil multiplies the damage, because yesterday’s breakdown products are still sitting in the pan when today’s frying begins.
Your kadai actually shows you this happening. Oil that has darkened, thickened, foams around the food or smokes at a lower temperature than before is oil that has chemically changed. That colour is not seasoning. It is a progress report on oxidation, and once the oil has degraded, no amount of straining brings it back.
What oxidised oil does inside the body
Your cells produce a certain number of free radicals, unstable molecules that damage whatever they touch, as a normal by-product of burning fuel in the mitochondria, the tiny power stations inside each cell. The body maintains antioxidant defences to mop these up, like a municipal team clearing the day’s rubbish. Trouble starts when the rubbish arrives faster than the team can clear it. Scientists call that state oxidative stress, and heavily oxidised cooking fats pour an external load directly on top of the internal one.
Over time, this surplus damages proteins, fats and even DNA. Research has linked higher intake of certain refined and repeatedly heated oils with a greater risk of metabolic problems, including type 2 diabetes, and long-term oxidative stress is implicated in cardiovascular disease, declining muscle quality and the neurodegenerative changes seen in Alzheimer’s and Parkinson’s disease. The effect is amplified in a body already dealing with insulin resistance, inactivity or muscle loss, which is precisely the situation many adults are in without knowing it.
The stress and convenience loop
There is a behavioural side to this as well. Stressful, overloaded days push us toward convenient food, and convenient food in India usually means something fried or something packaged. Street vendors and many commercial kitchens reuse oil far more aggressively than any home cook would, simply because oil costs money. Packaged namkeen and instant snacks are often fried in refined oils long before they reach you. So the more stressed and rushed life becomes, the larger this hidden oxidative load grows, at exactly the time the body is least equipped to handle it.
Practical steps for your kitchen
None of this requires abandoning your favourite food. It requires handling fat with the same care your grandmother gave her spices. At BFLL we see such kitchen-level corrections as small, practical moves in the larger shift from degeneration toward regeneration.
1. Stop reusing frying oil
This is the single biggest change. Fry with only as much oil as the dish needs, and let one use be its life. If discarding feels wasteful, treat that feeling as a push to deep-fry less often rather than as a reason to reheat degraded oil.
2. Match the method to the heat
Reserve high-heat frying for occasions. Everyday cooking can lean on steaming, pressure cooking, roasting and a normal tadka, which uses seconds of heat and a spoonful of fat rather than a litre held at frying temperature.
3. Choose less processed fats where you can
Traditional cold-pressed or kachi ghani oils retain more of their natural antioxidants than heavily refined ones. They cost more per litre, but if the first two steps reduce how much oil you use, the budget often balances. Rotating between one or two good oils also spreads your fat intake sensibly.
4. Store oil like it matters
Oxidation continues slowly in the bottle. Buy smaller packs, close the cap properly, and keep oil away from the stove’s heat and the window’s light rather than parked beside the burner.
5. Shrink the outside-food share
You control your own kadai. You cannot control the one at the stall. Keeping street-fried and packaged snacks as weekly treats rather than daily habits cuts the largest and least visible part of this load.
What you can start this week
- Retire today’s frying oil after one use instead of pouring it back into the container.
- Do a bottle audit. Check which oils you own, when they were opened and where they sit. Move them away from heat and light.
- Plan two fry-free days and cook those meals by steaming, roasting or pressure cooking.
- Swap one packaged fried snack for roasted chana, fruit, curd or a homemade option.
- Pair the oil change with the foundations: a little strength work, enough protein and a proper night’s sleep, because oxidative stress is fought on several fronts at once.
Frequently asked questions
Is any oil safe for deep frying?
Occasional frying in fresh oil, at a sensible temperature, in a home kitchen is a very different exposure from eating food fried in oil reused for days. Frequency and reuse matter more than the brand on the bottle. Keep frying occasional and the oil fresh.
Are cold-pressed oils always healthier?
They generally retain more protective compounds, which is a real advantage. But they are still concentrated fats, and a kitchen drowning its food in cold-pressed oil has not solved the problem. Quality, quantity and handling all count.
Is ghee better than refined oil?
Traditional fats like ghee are reasonably stable at cooking heat and have a long place in Indian kitchens. Used in modest amounts, ghee can sit comfortably in a sensible diet. No single fat is magic, though, and quantity still decides much of the outcome.
What should I do with used frying oil?
Do not pour it back for another round, and avoid tipping it down the drain where it clogs the pipes. Let it cool, collect it in a waste container and discard it with solid waste, or find a local collection point if one exists near you.
Medical disclaimer: This article is for education only and is not a substitute for personalised medical advice. Always consult a qualified healthcare professional before changing your treatment, diet or exercise programme.
Compiled and written by Soumick Mondal Raj, Founder and CEO of BFLL, Holistic Health Consultant.