Nutrition Diet: What's the unhealthiest fat and why it should be avoided

October 3, 2025 •

2 min read

According to the World Health Organization (WHO), more than 278,000 deaths each year globally can be attributed to the intake of industrially produced trans fats. In the landscape of nutrition, the question of what's the unhealthiest fat has a clear and decisive answer: artificial trans fats, also known as trans-fatty acids. These man-made fats pose a significant risk to heart health and should be avoided entirely for a healthier diet.

Quick Summary

Artificial trans fats are the most harmful dietary fat, raising 'bad' LDL cholesterol and lowering 'good' HDL. Found in many processed and fried foods, they increase the risk of heart disease and inflammation. It is crucial to read labels carefully to avoid them and prioritize healthier unsaturated fats.

Key Points

Artificial Trans Fats Are Worst: Industrially produced trans fats are the unhealthiest, negatively affecting LDL and HDL cholesterol.
Trans Fats Cause Inflammation: Artificial trans fats contribute to inflammation, a risk factor for chronic diseases.
Saturated Fat Requires Moderation: Saturated fats are less harmful than artificial trans fats but should be consumed moderately as part of an overall healthy diet.
Prioritize Healthy Fats: Monounsaturated and polyunsaturated fats are beneficial for heart health.
Read Labels Carefully: Look for "partially hydrogenated oil" on ingredient lists to avoid hidden trans fats.
Dietary Context Matters: The impact of fats depends on the overall diet; replacing unhealthy fats with healthy ones is recommended.

What makes artificial trans fat the unhealthiest?

Artificial trans fat is created through hydrogenation, a process that solidifies liquid vegetable oils. This enhances shelf-life and texture but forms a damaging fatty acid structure. Health experts note it negatively impacts heart health by elevating harmful LDL cholesterol while reducing beneficial HDL cholesterol. Its severity led regulatory bodies like the FDA to ban partially hydrogenated oils.

The damaging effects of trans fat

Trans fats contribute to inflammation, a risk factor for chronic diseases like heart disease, stroke, and diabetes. They offer no health benefits. Even a small increase in intake can significantly raise the risk of coronary heart disease.

Where are artificial trans fats found?

Industrially produced trans fats can be found in various foods, including fried fast foods, commercially baked goods, packaged snacks, some margarines, shortenings, and refrigerated dough products.

Saturated fat: The 'in-between' fat

Saturated fat is found in animal products and some plant oils. It raises LDL cholesterol, and its overall effect on heart health is complex and may depend on the diet. Replacing saturated fat with unsaturated fats appears beneficial, while replacing it with refined carbohydrates may be harmful.

How to make smarter choices with saturated fats

Moderation is advised for saturated fats. Opt for leaner meats, lower-fat dairy, and non-tropical oils, focusing on the overall dietary pattern.

Healthy fats: Monounsaturated and polyunsaturated

These fats are considered beneficial for heart health. Monounsaturated fats are present in olive oil, avocados, nuts, and seeds. Polyunsaturated fats, such as omega-3 and omega-6 fatty acids, are found in fatty fish, walnuts, flaxseeds, and certain vegetable oils.

Comparison of dietary fats


Feature	Artificial Trans Fat	Saturated Fat	Unsaturated Fat (Mono/Poly)
State at Room Temp.	Solid or semi-solid	Solid	Liquid
Effect on LDL	Increases significantly	Increases	Decreases
Effect on HDL	Decreases	Increases (but overall ratio worsens)	Increases
Health Impact	Highly harmful, no benefits	Moderate risk (context-dependent)	Highly beneficial
Primary Sources	Fried foods, processed baked goods, shortening	Fatty meats, high-fat dairy, coconut oil	Olive oil, avocado, nuts, seeds, fatty fish

Reading nutrition labels to spot unhealthy fats

To avoid artificial trans fats, examine the ingredient list for “partially hydrogenated oil”. Labels can state "0g trans fat" if the amount is below 0.5 grams per serving. Prioritize products with less saturated fat and more healthy unsaturated fats.

Conclusion

Artificial trans fats are the most harmful dietary fat, significantly increasing heart disease risk through negative impacts on cholesterol and inflammation. While saturated fat needs moderation and consideration of the overall diet, prioritizing monounsaturated and polyunsaturated fats from whole foods is beneficial. Checking labels for "partially hydrogenated oil" is key to avoiding artificial trans fats. Informed choices about fats are crucial for health. More information on healthy eating is available from resources like the {Link: American Heart Association https://www.heart.org/en/healthy-living/healthy-eating/eat-smart/fats/trans-fat}.

Frequently Asked Questions

Artificial trans fat raises 'bad' LDL and lowers 'good' HDL cholesterol, significantly increasing the risk of heart disease and stroke. It also causes inflammation.

No. Artificial trans fats from hydrogenation are harmful. Small amounts of natural trans fats in meat and dairy are not considered a major health concern.

Check the ingredient list for "partially hydrogenated oil". Labels can show "0 grams trans fat" even if small amounts are present, so the ingredient list is key.

No, saturated fat is not as harmful as artificial trans fat. Saturated fat is linked to higher LDL but its overall effect is more complex; artificial trans fats are significantly more damaging.

Healthy unsaturated fats are found in avocados, olive oil, canola oil, nuts, seeds, and fatty fish.

Replacing saturated fat with refined carbohydrates is not recommended as it can be detrimental to heart health. Instead, replace saturated fats with healthy unsaturated fats.

All fats are calorie-dense. Excessive intake, even of healthy fats, can lead to weight gain if calorie intake exceeds energy use. Moderation is important.