I am told that the rule of thumb is that any fat that is solid at room temperature should probably be avoided. Examples that come to mind are lard (pork and bacon fat), the fat of red meat like beef and mutton (I guess that's called tallow), trans fats, and saturated fats.
It's not an opinion, and it's not based on anything in particular. It is what I have come to understand from everything that I've heard and read over the last 50 years. Here is a quick and dirty google search result:
The "bad" fats are primarily considered to be trans fats and, to a lesser extent, saturated fats. These fats can negatively impact your health by raising LDL ("bad") cholesterol levels and are associated with an increased risk of heart disease, stroke, and other chronic health issues.
Trans Fats (Avoid When Possible)
Trans fats, particularly artificial trans fats, are considered the most harmful for your health. They are created through a process called hydrogenation, which turns liquid vegetable oils into solid fats.
- Health Effects: Trans fats raise your LDL (bad) cholesterol and lower your HDL (good) cholesterol, a "double whammy" for heart health. They also increase inflammation in the body.
- Commercially fried foods (e.g., French fries, doughnuts, fried fast food)
- Baked goods (e.g., cookies, cakes, pastries, crackers)
- Stick margarine and vegetable shortening
- Processed snack foods, such as microwave popcorn
- Identifying them: While food labels may list "0 grams trans fat" if there is less than 0.5g per serving, you should always check the ingredient list for "partially hydrogenated oils".
Saturated Fats (Use Sparingly)
Saturated fats are typically solid at room temperature and primarily come from animal products, though some plant-based oils are also high in them.
- Health Effects: Consuming too much saturated fat can raise your LDL cholesterol levels. While some recent research has questioned the strength of the link to heart disease risk, most health organizations, including the American Heart Association, still recommend limiting intake and replacing them with healthier unsaturated fats.
- Fatty cuts of beef, pork, and lamb
- Poultry skin and dark meat chicken
- High-fat dairy products (e.g., butter, cheese, whole milk, ice cream, cream cheese)
- Tropical oils (e.g., coconut oil, palm oil, cocoa butter)
- Lard and bacon fat
For optimal health, it is recommended to limit intake of saturated fats (to less than 10% of daily calories) and replace them with heart-healthy monounsaturated and polyunsaturated fats found in foods like fish, nuts, seeds, and vegetable oils (olive, canola, avocado).
