Trans Fat: What It Is and How and Why to Avoid It

Good morning, my friends – I thought it would be fun to mix it up today and share a nutrition hot topic related post! I’m hoping to make this a more regular feature on the blog (maybe once a month or so), if you all are interested. What sort of other nutrition hot topics would you like to see featured/analyzed here on the blog?


For today’s post, I’ll be sharing some information about trans fat – what it is, and also why (and how) to avoid it! I hope you find it helpful.

trans fat

For a while you were most likely familiar with the fact that nutrition fact labels included the amount of fat. Total fat, saturated fat, and sometimes even mono- or poly-unsaturated fats. More recently, you may have noticed that trans-fats have been added to the nutrition facts label. But what are these trans-fats and should you avoid them?

Trans-fats naturally occur in small amounts in animal foods, however, most of the trans-fats in our food supply are introduced to food products through a process called hydrogenation. Simply put, this process adds hydrogen to liquid fat (oil) and turns that fat into a solid substance. We actually did this procedure once ourselves in organic chem lab when I was doing my prerequisites for grad school! So – why put oils through this process? Good question. Hydrogenating oils does three main things:

  • Increases shelf life
  • Enhances flavors
  • Impacts texture

Although these characteristics seem like positive changes, especially to our taste buds, the addition of trans-fats has detrimental effects on our health, even in small amounts. Adversely, within the body, trans-fats:

  • Increases LDL, or “bad” cholesterol levels
  • Decreases HDL, or “good” cholesterol levels
  • Increases risk for heart disease, diabetes, and cancer

Trans-fats commonly exist in products such as: cookies, crackers, frostings, margarine, vegetable shortening, pre-mixed cake mixes, fried foods, snack foods, and more. You can reduce your intake of trans-fats by limiting your consumption of these packaged foods and by checking the food labels when you do purchase them. Foods that contain trans-fats will include “partially-hydrogenated oils” in the ingredient list – be sure to look for it and avoid it if possible! For example, many cheaper/more processed nut butters include partially-hydrogenated oils – make sure that when you buy nut butter, the only ingredients listed are the nuts and (if you like) a little salt. Or, you can do the “grind your own” approach they offer at some health food stores like Whole Foods. This is usually what I do!


Although food labels must now disclose the amount of trans-fats in the product, be cautious. The FDA allows any product with less than 0.5 grams per serving to make the claim “0g Trans-Fats”. Although 0.5 grams of trans-fats per servings sounds miniscule, beware. The American Heart Association recommends limiting your total daily consumption of trans-fats to 1% of total calories per day (i.e. 2,000 calorie diet = 2 g trans-fats per day), or as little as possible. If you are consuming foods with trans-fats, even if it has 0.5 grams per serving, your consumption can add up quickly!

So, what are the take away messages?

  • Read food labels
  • Avoid foods containing “partially hydrogenated oils”
  • Limit your consumption of trans-fats for heart health
  • No more than 1% of daily calories

Do you avoid trans-fat in foods? Are you a label reader? Besides making sure to avoid trans-fats, I also look at ingredient lists to make sure that I recognize all the ingredients – and that the lists aren’t a mile long! Real food all the way, my friends.



  1. 1

    I like this idea of nutrition hot topic posts! I do read labels, but I was always curious if 0 trans fats was truly 0. I know that a food can be labelled 0 calories if it has under a certain amount.

  2. 2

    I love this post! I hope you do some more… the one thing that always gets me is sugars! I keep track of everything I eat in MyFitnessPal which is great. BUT I am always over in sugar but mostly from fruits and veggies. So I guess just a deep dive into that would be so helpful! Is it okay if I am over sugars including fruits and veggies and not over sugars when I just count “processed” sugars.

    As far as trans fats this is so interesting and so helpful so thank you for this post!. One thing that always confused me is that when it says “total fat” and then the saturated fat and trans fat does not equal the “total” fat does that mean the rest are unsaturated fats?

    Thank you again for this post!!! :)

  3. 5

    Thank God for this post! It’s so sad because though most people know trans fat is bad, they have no idea that “partially hydrogenated oil” is what to look out for! Great recap.

  4. 6

    I think it’s a great idea to do posts like this! I’d be really interested in various vitamins and the best sources to get them. I have osteoporosis so I’d be really interested in calcium, vitamin d, etc. Also, I know that some vitamins are best absorbed if eaten with other vitamins, but any clarification on that would be great!

  5. 7

    Thanks for posting this ! I’ve always known trans fats were “bad” and have avoided them but never really knew the why of it before.

  6. 8

    great post! what is the difference between “fully” and “partially” hydrogentated vegetable oils? (reading my PB label now :))

    • 9

      Great question! Partially hydrogenated oils contain trans fats but fully hydrogenated oils do not. :) Full hydrogenation increases the amount of saturated fats, mostly in the form of stearic acid, but stearic acid does not raise LDL cholesterol levels. That makes fully hydrogenated fats less harmful than partially hydrogenated fats.

      • 10

        Whoa really? I thought fully hydrogenated oils contained trans fats. But when I think about it, that means the carbon chain is FULLY SATURATED IN HYDROGENS which would make it a saturated fat. (Saturated in hydrogens). Trans fats by definition would have to have at least a few hydrogens missing. I wish you would have included diagrams of trans fats and saturated fats and then compared to cis-fatty acids and discussed the difference and which are naturally occurring. That is my two cents. Maybe some pics of labels with ingredient lists that have trans fats hiding in them? You can google images of losts of labels online

        • 11

          Yes, exactly – fully saturated with hydrogens, which were forced on during the full hydrogenation process. Pretty interested stuff. I didn’t want to get too complicated/science-y for this post, but thank you for the feedback!

          • 12

            I understand, but I also think it’s important for the general public to be shown that science isn’t magic- it can be made relatively simple to follow and easy to understand. So sometimes I think it would be worth including, for the educational benefit of the masses. People sit around reading ENews all day but think they can understand a simple difference in the presence or lack of a hydrogen atom on a carbon backbone. They totally can!

  7. 14

    I would definitely be interested in reading more posts like this.

    I’m usually a label reader. Though if I’m in a hurry sometimes things will be put in the grocery cart without having a look at the label.

  8. 15

    Very good information! I am slowly making the transition to clean eating. I just looked at my peanut butter jar and there it is! Will be replacing that jar soon. Keep the good advice coming!

  9. 16

    Great info I actually just had my cholesterol checked and want to improve it!

  10. 17

    Good post. Good topic!
    I think it would be great if you could discuss coconut oil and despite the high saturated fat content in that product everyone seems to be on board with its purported healthy benefits. Is coconut oil really that good for you?

  11. 21

    I read labels and try to avoid any artificial ingredients, including hydrogenated fats.

  12. 22

    Love this educational post! Those tricky FDA peeps really try to sneak us the bad stuff!

  13. 23

    I love the idea of nutrition hot topic post. Great idea and I will look forward to reading!

  14. 24

    A food processor is worth it JUST for the ability to make your own nut butters from scratch. No trans fat, AND you get to choose your own saltiness, and even mixtures of nuts. Yum!

  15. 26

    I get so confused by the conflicting advice. The Dr Fuhrman, Barnard, McDougall theories that closely match the China study way of thinking vs Mercola, Sally Fallon, Paleo non-grain way of thinking. I am trying to do what I can to prevent cancer and other western diseases. But it’s all so conflicting and I want to feed my kids the right one!

    • 27

      I agree a great topic – would like to get Anne’s feedback on these different methods of eating. I struggle with changing my regular diet for vegan/vegetarian for improved heart health.

  16. 28

    Thanks for this! I’m definitely a label reader, and I do a lot of my shopping at Trader Joe’s to avoid a lot of the over-processed foods you usually find in grocery stores.

  17. 29

    Great post, thanks for sharing! I have become much more diligent in reading labels – its a must!! One thing that would be super helpful for me is a post on portion control. I’ve realized I don’t really know the ‘proper’ portions for different foods…any help would be greatly appreciated :)

  18. 30

    Great post. You made what can seem like a complicated issue so simple to understand! I definitely have been following the method of “recognizing all of the ingredients.” An easy way to make sure it’s not processed!

  19. 31

    Thanks for this! Keep them coming!

  20. 32

    Great post! I would love to learn more about gmo’s and the effects they can have on dairy products. Also artificial colors would be great. Thanks!!!

  21. 33

    Great post! I’d love to see more nutrition topic posts like this. I try to read labels whenever I buy packaged foods. I mostly look at the ingredient list and try to buy whichever has the least ingredients. I love that you shared the tip about hydrogenated oils because I think that’s easy to overlook.

  22. 34

    I second the vote for more nutrition posts–this one was very informative! Maybe a future post could be on gluten. I’m seeing more processed foods in the grocery store labeled “gluten-free”. Is gluten intolerance that widespread? If you’re not gluten intolerant is there a nutritional reason to avoid it?

  23. 35

    Yes, more nutrition posts! Can you do a blog post on GMOs and how to determine what foods contain GMOs? I can’t always do organic….

  24. 36

    Thanks for the refresher, RD ;)

    You have an intern!? That’s so cool!!

    • 37

      I actually have 3 interns! :) They’re each just doing a few hours a week for me (it’s not an official dietetic internship program or anything), and they are all virtual, but it’s been super helpful so far – and hopefully helpful and interesting for them, too!

  25. 38

    Butter vs. margarine?

  26. 39

    I’d love to hear your take on the paleo diet craze!!!

  27. 41

    Hi Anne! Thanks for sharing this. I find it extremely interesting- I was wondering if in one of your future posts you can explain just how to read a nutritional label. I find that I usually focus on one thing but am usually off-base in wanting to focus on one stat, say calories. For those of us not in the dietetics field, I feel like it would be great to read and learn about as it is really important!

  28. 42

    Very very informative post – thank you for taking the time to research and share with us!

  29. 43

    One HUGE nutrition debate you could talk about is… Whether or not dairy is healthy. I would love to hear your opinion on that matter as I have a VERY LARGE opinion of it myself! ;)

    No trans fat in my life… Only a TINY TINY bit from natural sources – animal meats, CLA.

  30. 44

    This is really helpful, Anne, thanks!

    And hope the foot feels ok still!?

  31. 46

    Posts like these are very helpful as I learn more about nutrition and how to make healthier choices. Looking forward to future posts!

  32. 47

    Love this feature!!
    Others that I would like are as follows:
    1. How to increase your HDL?
    2. Ways to improve your gut health?
    3. What vitamins should you supplement (if any)?
    4. Why is grass fed beef good for you vs other types of beef?
    5. What is the difference between all the different types of eggs (cage free, pasture raised, free roaming etc.)?
    6. What foods can you eat to improve your mood?
    7. What are healthy fats and why are they good for you?

  33. 48

    Great post, looking forward to reading more like it in the future!

  34. 49

    Thank you for sharing, Anne! It really frustrates me that the limit for labeling trans fats is 25% of our daily consumption limit. I solve that problem by looking at labels for scary things like partially-hydrogenated oils or other ingredients I don’t recognize, but I honestly think that’s too much to ask from “the average consumer.” I would LOVE to see more of these features! I’d love to hear your thoughts on stevia, and I’ll second the GMO idea above (and what YOU personally buy organic – just avoiding the Dirty Dozen? all organic?)

  35. 50

    Love that you are using your RD to create informative posts. We need this, especially in the HLB world so PLEASE keep them coming.

    The most important issue I think you could touch on is the safety of soy products. There is SO MUCH PROPOGANDA out there saying soy is bad for you but there is NOT RESEARCH TO SUPPORT IT. In fact, the research that has been done supports using soy as part of a balanced diet to lower your risk of chronic disease. PLEASE DEBUNK THIS ONCE AND FOR ALL. Soy gets such a bad rep.

  36. 52

    Great post! I hate when food manufacturers can be tricky with ingredient labels. I wasn’t aware of the trans fat issue. I do know that a lot of spray oils (which I use a lot) say 0 calories, but really that’s only in like a 10 second spray or something ridiculous!

  37. 53

    Since so many folks are asking about GMO’s, they might like to check out a website which has lots of information:
    Could you research health concerns about microwaving food. I have read that it makes all food, water and other liquids more acid forming in our bodies, whereas our bodies generally need to have more alkaline forming foods and liquids. Also, that microwaving robs body of B vitamins. And some other negative things which I can’t remember.

  38. 54

    Thanks for the easy to understand nutrition post! I really liked it and I hope you keep these up on the blog! :)

  39. 55

    Love nutrition posts!


  1. […] trans fat (here’s a blog post about what is trans fat and how and why to avoid it) – this has been shown to increase LDL, decrease HDL, and up risk for diabetes, heart disease, […]

  2. […] Well, in addition to the increase in carbohydrate and sugar consumption due to the low fat diet craze, the third point here is that processed vegetable fats/oils were also being pushed to replace animal fat, with the assumption that they would be better for health because they were lower in saturated fat. This led to the development and promotion of margarine, and other baking fats that were made from vegetable oil, and these products were used in a lot of processed foods, too. These products were created using a process called hydrogenation, which converts a liquid oil (like soybean or corn oil) to margarine or vegetable shortening that is solid at room temperature, and creates something called trans-fats in the process. At the time, we didn’t realize it, but we now know that trans-fat has been found to increase LDL, or “bad” cholesterol levels, to decrease HDL, or “good” cholesterol levels, and to increase risk for heart disease, diabetes, and cancer. Oops, right? (If you’re interested to read more about this, check this post out: what is trans-fat and how and why to avoid it.) […]

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