What is Fat?
- Fats come in both solid and liquid forms – solid fats include butter, lard and the fat visible on meat. Liquid fats include sunflower, corn and olive oils.
- Fats can also be divided into visible and invisible fats. Visible fats, such as butter and the fat on meat are easy to spot and cut out. But invisible fats, such as those in cakes, biscuits, dairy foods like cheese and fried foods are more difficult to see and we may not even be aware that they are present in some foods.
- Fats can also be divided into four types – polyunsaturated fats, saturated and trans and monounsaturated fats.
Polyunsaturated fat – Comes mainly from vegetable sources such as sunflower oil or seeds and is also found in oily fish such as mackerel or sardines. There are two different groups of polyunsaturates containing fatty acids that are essential to our health. They must be obtained through the diet we eat because the body cannot make them. The type of polyunsaturates found in the oils can reduce blood cholesterol levels, but that found in oily fish appears to have no effect on blood cholesterol, although they do make the blood less ‘sticky’ which in turn, makes the blood less likely to clot and block the blood flow to the heart.
Saturated fat – Is found in foods from animals such as meat, cheese, butter and cream. Many baked goods such as cakes, biscuits and pastries are also high in saturated fats. Excessive intake of these fats can increase the ‘bad’ cholesterol levels [LDL] and heart disease.
Trans fat – Also called ‘hidden fats’ or ‘trans fatty acids’, behave in a very similar way to saturated fats and they too have been linked to raised ‘bad’ cholesterol levels [LDL] and heart disease. They are made from vegetable oil and found in nearly all convenience foods but also occur naturally in some dairy products, in beef and lamb. Just one gram of trans fat a day can increase the risk of heart disease. It is not difficult to eat one gram a day – a KFC of crispy strips of chicken and fries, McDonalds McNuggets and fries or a Burger King Whopper with fries all contain significantly more than this.
Trans fats are being cut from many well known brands such as Horlicks, Mars and Weetabix but beware because it is not compulsory for manufacturers to list trans fats on their food labels.
Monounsaturated fat – This is found in significant amounts in most types of nuts, oily fish, avocados and olive oil. It does not raise blood cholesterol and there is some evidence to show that it may also help to reduce cholesterol levels.
More facts about fats
This information takes the next step and looks at what the food manufacturers do when they produce lower fat versions of standard foods that are high in fats, such as cheese, mayonnaise, biscuits and crisps. It is often the fats in foods that make them taste so nice, smell nice and give a creaminess to the texture, so manufacturers use a ‘fat replacer’ to make them taste better and attractive enough for us to want to eat them. Other low fat products such as skimmed milk, do not have fat replacers as the fat content is reduced by simply removing the fat eg in low fat crisps the fat content is lowered by reducing the amount of fat left on the crisps, leaving the actual contents of potatoes, vegetable oils and salt the same. Needless to say, the food manufacturers have spent years finding fat replacers that satisfy our taste buds and there are different ways of doing this.
Mimicking the effect – These fat replacers are designed to mimic the texture and effect of fat. They are usually based on carbohydrates and proteins and may be extracts of fruits, oats or seaweed. They are listed on the food labels as whey powder, gelatin, lecithin, starches, carrageenan, cellulose, guar gum, locust bean gum and maltodextrins. These additives are also used in standard foods but they have a more critical role to play in low fat foods. These types of fat replacers cannot usually be used in frying or baking because the heat affects them.
In some foods water and fats are mixed into an emulsion to give the impression of creaminess but when the fat is reduced the consistency is not the same so emulsifiers are used [eg lecithin] in spreads sauces and salad dressings.
Fats also have a slippery feeling in the mouth and protein replacers, such as milk protein whey, are used. The small particles of protein in the whey act like ball bearings and slide over each other to feel like fat on the tongue. These are used in yogurts, ice creams and mayonnaise.
Modifying the fat – new technology has focused on developing fat-based fat replacers that work in the same way as fats. They have the same textures as fats but can be used for frying and baking. They have been chemically modified to give fewer calories than standard fats. These sound promising but there are some problems yet to be solved because one product, Olestra approved in the US but not used in the UK, is not absorbed into the blood stream and passes out of the body unchanged. This can cause unpleasant side effects.
Hopefully this will help you to know a little bit more about the products you are buying to try to reduce your fat intake. However, having written the article I feel generally quite put off all food for the moment!