How trans fats affect your health

How trans fats affect your health and how to avoid them for good

Updated: May 08, 2024Veronika Larisova

The Chief Nutrition team love food and don’t like suggesting cutting out entire food groups. For us, it’s all about a whole food approach, strategic moderation, understanding portion sizes and paying attention to your own individual genetics and body signals – everybody is different after all. But there is one kind of food we think should be tossed in the bin for good...

The food we’re talking about is man-made trans fats.

Why do we emphasise the ‘man-made’ part? Because trans fatty acids are actually found in grass-fed meat products too but there’s a BIG difference between naturally occurring and industrially produced trans fats. The former is good for heart health and helps keep you lean, while the latter creates inflammation, contributes strongly to chronic disease and will make you pack on fat around your belly – just where it’s most dangerous and you really don’t want it!

You see man made trans fats have a unique chemical structure, which makes them incredibly detrimental to your health (both short and long-term) and also really hard for your body to metabolise (meaning you will pack on a lot more fat from eating them).

This kind of fat is created by pumping hydrogen molecules into vegetable oils, a process that totally changes the chemical structure of the oil, transforming it from a liquid into a solid and making it very handy for enhancing the texture of foods and increasing shelf life. It also makes whatever food it’s being added to seriously dangerous for your health.

In the health industry, trans fats are often referred to as “shape shifters” and the bottom line is that the body doesn’t know what to make of the end product, and as a result havoc is created in the process of cell metabolism.

The bottom line is that eating trans fats negatively affects everything from your heart health and cholesterol levels, to inflammation and the likelihood of developing chronic disease, to hormone and blood sugar balance, as well as fat storage.

I can’t help it – every time I see someone eating foods high in trans fats like deep fried chips or battered fish, donuts and margarine, or highly processed foods laced with vegetable oils, I just want to walk over and gently remove the plate. People really don’t realise how bad this stuff is for them and how effective simply removing them from your diet can be in turning your health (and waistline!) around.

Getting rid of industrial trans fats – as in, zero intake – is WAY more important than worrying about going ‘paleo’ or ‘raw’ or whatever the current diet fad might be.

When it comes to the naturally occurring trans fatty acids found in grass-fed meat and dairy however, which is called vaccenic acid, it’s a different story. This is the good stuff and it has a lot of positive outcomes for your health.

Food with bad trans fats to avoid

If you’re confused about what to avoid, start with chucking these things in the bin… and don’t let them back in to your diet:

  • Deep fried foods like hot chips and battered fish
  • Margarine
  • Processed snack foods that have any level of trans fat on the nutrition panel
  • Pies and pie crusts
  • Donuts
  • Shortening
  • Microwave popcorn
  • Fast food like fried chicken and processed meats in hamburgers
  • Non-dairy coffee creamers
  • Most long-life packaged biscuits and sweet rolls
  • Some soft-serve ice-creams
  • Packaged crackers (mostly the fried or long shelf-life kind)
  • Some frozen dinners and microwave meals (check the panel)
  • Ready-to-eat/instant noodles
  • Packaged puddings 

When it comes to the rest of your diet, it’s very individual but a little bit of all the good stuff is generally a good approach for healthy people looking to optimise their health and body shape.

Here’s a rough guide to portion sizes per meal, as recommended by legend nutritionist John Berardi from Precision Nutrition, who gets it right about 99.99999% of the time:


  • 1 palm of protein dense foods
  • 1 fist of vegetables
  • 1 cupped handful of carb dense foods
  • 1 thumb of fat dense foods


  • 2 palms of protein dense foods
  • 2 fists of vegetables
  • 2 cupped handfuls of carb dense foods
  • 2 thumbs of fat dense foods


  1. Remember, you are unique and you may need to play with the amounts given here based on how you feel, how much you exercise and your own particular health goals or challenges.
  2. Proteins – stick with clean, untarnished animal proteins, or unprocessed vegetarian substitutes
  3. Vegetables – when it comes to green and cruciferous veggies, eat as many as you like – there’s no limit!
  4. Carbs – exclude overly processed/refined carbs most of the time. Stick to basic grains and starchy veggies like rice, oats, corn, quinoa, amaranth, buckwheat, potato, sweet potato, pumpkin, or a quality sourdough/seeded bread.
  5. Fats – the healthiest are traditional fats like olives and olive oil, avocado, nuts, seeds, chia seeds, a little full fat dairy or coconut milk/oil, egg yolk or butter/ghee. AVOID – always (always!) avoid trans or hydrogenated fats discussed above.

Want a bit more info on the topic? Check out this article from Mark’s Daily Apple.

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