What is the most unhealthy fat?

November 1, 2025 •

2 min read

According to the World Health Organization (WHO), over 278,000 deaths annually are attributed to the intake of industrially produced trans fat, widely considered what is the most unhealthy fat. These synthetic fats, once common in processed foods, have a uniquely damaging effect on cardiovascular health.

Quick Summary

Artificial trans fat, created via partial hydrogenation, is the most damaging type of dietary fat, significantly increasing heart disease risk by elevating LDL and lowering HDL cholesterol.

Key Points

Artificial Trans Fat is the Worst: Industrially produced trans fat, made through partial hydrogenation, is the most harmful fat for your health with no known benefits.
Double Threat to Cholesterol: Artificial trans fat is uniquely damaging because it both raises LDL ('bad') cholesterol and lowers HDL ('good') cholesterol.
Inflammation is a Major Risk: Consumption of artificial trans fat increases systemic inflammation, a primary risk factor for heart disease and other chronic illnesses.
Found in Processed Foods: Common sources include commercially fried and baked goods, margarine sticks, and processed snacks containing partially hydrogenated oils.
Replacement is the Solution: The best strategy is to avoid artificial trans fats entirely by choosing whole foods and replacing them with healthier unsaturated fats.

The Unrivaled Harm of Artificial Trans Fats

Of all the dietary fats, artificial trans fat has no known health benefits and is unequivocally the most damaging to human health. Created through an industrial process called partial hydrogenation, this fat adds hydrogen to liquid vegetable oils, turning them into a semi-solid fat. While initially used for its cost-effectiveness and shelf-life benefits, research has revealed its profound harmful effects, leading to bans in many countries.

How Trans Fats Damage Your Health

The primary danger of artificial trans fat is its unique impact on cholesterol. It raises low-density lipoprotein (LDL) or "bad" cholesterol, and lowers high-density lipoprotein (HDL) or "good" cholesterol. This contributes to the buildup of plaque in arteries (atherosclerosis), restricting blood flow. Artificial trans fats also promote systemic inflammation, a factor linked to heart disease, stroke, and type 2 diabetes. Even small amounts significantly increase the risk of coronary heart disease.

Sources of Artificial Trans Fats

Despite regulations reducing their use, artificial trans fats can still be found in some processed and fried foods, especially where regulations are less strict. Checking ingredient lists for “partially hydrogenated oils” is important.

Common food sources may include:

Fried foods (fries, doughnuts)
Baked goods (cookies, cakes)
Margarine sticks and shortening
Packaged snacks
Refrigerated dough
Some non-dairy creamers

Comparison of Major Fat Types

Comparing artificial trans fat to other fats highlights its unique dangers. Saturated fat, while less healthy than unsaturated fat, does not pose the same level of risk as artificial trans fat.


Feature	Artificial Trans Fats	Saturated Fats	Unsaturated Fats
Physical State	Semi-solid	Solid (e.g., butter)	Liquid (e.g., olive oil)
Primary Source	Partially hydrogenated oils	Animal products, tropical oils	Plant-based sources, fatty fish
Effect on LDL ('Bad') Cholesterol	Increases significantly	Increases	Decreases
Effect on HDL ('Good') Cholesterol	Decreases significantly	Little to no effect	Increases
Inflammation	Increases	Mixed evidence	Decreases
Overall Health Impact	Highly detrimental	Consume sparingly	Beneficial

Healthier Alternatives and Dietary Strategy

Replacing unhealthy fats with healthier options is crucial. Opt for sources rich in monounsaturated and polyunsaturated fats.

Tips for reducing unhealthy fat intake:

Use liquid vegetable oils like olive or canola oil for cooking.
Choose soft, non-hydrogenated margarines.
Increase whole, unprocessed foods.
Limit commercial baked goods and fast food.
Choose baked, steamed, or grilled foods over fried.

Conclusion

Understanding the impact of different fats is vital. While saturated fats should be limited, artificial trans fats are the most significant threat to heart health. By recognizing their dangers, identifying sources, and choosing healthier fats, you can protect your cardiovascular health and improve overall well-being. A diet emphasizing whole foods and healthy unsaturated fats is the best way to minimize risks associated with the most unhealthy fat. Learn more about heart-healthy choices from the American Heart Association.

Frequently Asked Questions

Artificial trans fats are uniquely harmful because they both raise your LDL ('bad') cholesterol and lower your HDL ('good') cholesterol, which significantly increases your risk of heart disease.

To identify artificial trans fats, you should look for "partially hydrogenated oil" in the ingredients list. Manufacturers can label products as having "0 grams trans fat" if there's less than 0.5 grams per serving, so checking the ingredient list is crucial.

Natural trans fats occur in small amounts in meat and dairy from ruminant animals and have been shown to have similar effects on plasma lipoproteins as artificial trans fats. Some health recommendations suggest limiting consumption, though industrially produced trans fats are the primary concern.

Saturated fat is typically solid at room temperature and primarily comes from animal sources and tropical oils, raising LDL cholesterol. Artificial trans fat is semi-solid, created industrially from liquid oils, and has the dual negative effect of raising LDL and lowering HDL cholesterol.

Common sources include fried and baked commercial goods like French fries, donuts, cookies, cakes, as well as margarine sticks, vegetable shortening, and many pre-packaged snack foods.

Yes, healthier alternatives include liquid vegetable oils rich in polyunsaturated and monounsaturated fats, suchs as olive oil, canola oil, and sunflower oil. Replacing solid fats with these oils is recommended.

Yes, avoiding artificial trans fats is highly beneficial. Research shows that populations with lower trans fat intake experience a reduced risk of cardiovascular disease, and dose-response relationships indicate that greater reductions in trans fat lead to greater health benefits.