The difference between saturated and unsaturated fats

Figuring out which fats are good and bad can be quite confusing. In fact, you may just think all fats are terrible for your health - after all, the word has been given some pretty negative connotations. But as it turns out, fats are essential to our diets, though there are some you should avoid.

Fats, otherwise known as lipids, are essential to bodily functions. The American Heart Association (AHA) recommends that between 20% and 35% of your total daily calories should consist of fat. (1) But this is quite easy to achieve, as all fats are typically high in energy. A gram of fat provides roughly 9kcal of energy compared with just 4kcal for carbohydrate and protein.

There are two different types of fats - saturated and unsaturated - and while fats are vital to varied, healthy diet, the two types have very different sources and effects on our bodies.

Saturated Fats

Saturated fats get their name due to their chemical structure. While all fats consist of oxygen, carbon and hydrogen, saturated fats have the greatest number of hydrogen atoms possible with no double bonds - in other words they are 'saturated' with hydrogen.

What does all this chemistry jargon mean? Well for one, it means that saturated fats become solid at room temperature, which is why you might see fat running through cuts of red meat for example.

Some foods that contain high amounts of saturated fats are:

• processed meat - eg: hot togs, bacon & sausages
• certain plant oils - eg: coconut or palm kernel
• processed, packaged foods - eg: crisps, cookies and pastries
• dairy products - eg: cheese, butter and milk

Trans Fats

Trans fats, or trans-fatty acids, are a form of unsaturated fat. Natural trans fats are found in meat and dairy and several reviews have concluded that a moderate intake of these fats does not appear harmful. (3, 4, 5)

Artificial trans fats on the other hand are hazardous to your health. They are found in high concentrations in processed foods, as the chemical process used to create them gives them a very long shelf life so they are perfect for packed and fast foods. Countless studies have found that trans fats can lead to an increased risk of heart disease. (6, 7, 8)

Why limit your consumption of saturated fats?

Saturated fats are well known for being the least healthy of the two, as they can contribute to heart issues and overall health conditions.

Many studies have found that consuming high amounts of saturated fats could increase your low-density lipoprotein (LDL) levels - otherwise known as bad cholesterol. This in turn increases your risk of heart disease, as LDL contributes to atherosclerosis (plaque build up in your arteries). (9)

As such the AHA recommend a daily saturated fat intake of no more than 6% of your total daily calories (10) So, for the standard 2000-calorie daily diet, you should only consume 120 calories or 13 grams of saturated fats.

Unsaturated Fats

Unlike saturated, unsaturated fats are typically liquid at room temperature due to their chemical structure containing one more double bonds. More importantly, unsaturated fats are considered beneficial as they can improve blood cholesterol levels and ease inflammation. As a result, making sure you regularly consume unsaturated fat rather than saturated fat, is key to a healthy diet.

Sources of unsaturated fats:

• avocados and avocado oil
• olives and olive oil
• peanut butter and peanut oil
• vegetable oils, such as sunflower, corn, or canola
• fatty fish - eg: salmon and mackerel
• nuts and seeds, such as almonds, peanuts, cashews, and sesame seeds

Types of unsaturated fats

Unsaturated fats can be further categorised as:

• Monounsaturated: From a chemical standpoint, monounsaturated fats are simply fat molecules that have one double bond.

Found in: Olive, peanut, and canola oils, avocados, Nuts such as almonds, hazelnuts, and pecans, Seeds such as pumpkin and sesame seeds

• Polyunsaturated: These are fat molecules that have more than one double bond. The two major classes of polyunsaturated fats are omega-3 and omega-6 fatty acids.

Found in: Sunflower, corn, soybean, and flaxseed oils. Walnuts, flax seeds, fish, canola oil.

Ideally you want to consume more of the two fats above, while you limit your saturated fat intake, but specifically polyunsaturated fats could be the best of all. In one study, replacing saturated fat consumption with polyunsaturated fats reduced the risk of heart disease by 19%. (11)

Saturated vs unsaturated

Saturated and unsaturated fats are found in many different foods, and most often they are found together, as fatty foods contain a combination of fatty acids.

Despite that, most full fat dairy products, like butter and cheese, as well as processed meats and baked goods, tend to be high in saturated fats. While nuts, seeds and oils, tend to be good sources of unsaturated fats, with almost no trace of saturated fats.

The NHS recommends that: (2)