Fat is a nutrient. It is crucial for normal body function and without it
we could not live. Not only does fat supply us with energy, it also
makes it possible for other nutrients to do their jobs.
Fats, which consist of a wide group of compounds, are usually soluble in organic solvents and insoluble in water. Chemically, fats are usually known as triesters of glycerol and fatty acids (triester = one of three ester chemical groups).
At room temperature fats may be present in either liquid or solid form, this depends on their structure and composition. We tend to refer to fats which are liquid at room temperature as oils. Fats which are solid at room temperature are generally referred to as fats. The word lipids refers to both solid and liquid forms of fat. Below is a reminder breakdown of their meanings:
Over the last 50 years the percentage of people in most countries who are overweight has increased significantly. This is due to many factors, but NOT because people's fat intake has increased. Over the last five decades the consumption of carbohydrates as a percentage of total calorie consumption has increased dramatically - not fat consumption. Fat consumption does not make your body produce more insulin; carbohydrates do that. The more insulin your produce the more energy your body will store away as fat. When deciding how much fat to consume, remember that the answer is not simple - there are many types of fats, carbohydrates and proteins.
Sources: National Health Service (NHS), UK, The Mayo Clinic, Wikipedia, HHS (Department of Health and Human Services USA), NIH (National Institutes of Health, USA), American Heart Association
Fats, which consist of a wide group of compounds, are usually soluble in organic solvents and insoluble in water. Chemically, fats are usually known as triesters of glycerol and fatty acids (triester = one of three ester chemical groups).
At room temperature fats may be present in either liquid or solid form, this depends on their structure and composition. We tend to refer to fats which are liquid at room temperature as oils. Fats which are solid at room temperature are generally referred to as fats. The word lipids refers to both solid and liquid forms of fat. Below is a reminder breakdown of their meanings:
- Oils - Any fat which exists in liquid form at room temperature. Oils are also any substances that do not mix with water and have a greasy feel.
- Fats - All types. However, fats are commonly referred to as those which are solid at room temperature.
- Lipids - All types of fats, regardless of whether they are liquid or solid.
Examples of Fats
- Animal fats
Butter, lard, cream, fat in (and on) meats. - Vegetable fats
Olive oil, peanut oil, flax seed oil, corn oil.
Different categories of fats
- Saturated fat
Saturated fats are totally saturated, each molecule of fat is covered in hydrogen atoms. Nutritionists say saturated fats increase health risks if you consume too much over a long period of time. A large intake of saturated fats will eventually raise cholesterol levels, which can lead to cardiovascular disease and possibly stroke.
Where is saturated fat found?
The largest amounts of saturated fats can be found in meat (mammals), meat products, the skin of poultry, dairy products, many processed foods such as cakes, biscuits, pastries and crisps, as well as coconut oil. - Monounsaturated fat
Monounsaturated fat molecules are not saturated with hydrogen atoms - each fat molecule has only the space for one hydrogen atom. Health experts say the impact on health of monounsaturated fats is neutral - they are neither good nor bad for you. Many health professionals, however, do say that they reduce a person's risk of developing heart disease. The Mediterranean diet is full of monounsaturated fats.
Where are monounsaturated fats found?
Olives, ground nut oil, and avocados. - Polyunsaturated fat
There are a number of spaces around each polyunsaturated fat molecule - they are not saturated with hydrogen atoms. Nutritionists say polyunsaturated fat is good for our health, especially those from fish, known as the Omega-3 polyunsaturated fatty acids. Omega-3 polyunsaturated fatty acids protect us from heart disease as they lower blood cholesterol levels. Health care professionals say Omega-3 polyunsaturated fatty acids may also help reduce the symptoms experienced by people who suffer from arthritis, joint problems in general, and some skin diseases.
Where are Polyunsaturated fats found?
Oily fish (sardines, mackerel, trout, salmon and herring), safflower oil, grapeseed oil, and sunflower oil. - Trans fat
Trans fats are synthetically made, they do not naturally occur. Trans fats are created in an industrial process that adds hydrogen to liquid vegetable oils to make them more solid. They are also known as partially hydrogentated oils.
Trans fats might be monounsaturated or polyunsaturated, they are never saturated. A trans fat is a type of unsaturated fat with trans-isomer fatty acid(s). Therefore, trans fats have fewer hydrogen atoms than saturated fats.
Trans fats are not essential for human life and they most certainly do not promote good health. Consuming trans fats increases your LDL cholesterol level (bad cholesterol) and lowers levels of HDL cholesterol (good cholesterol), which in turn raises your risk of developing coronary heart disease and stroke.
Experts say that trans fats from partially hydrogenated oils are worse for your health than naturally occurring oils.
Trans fats have become popular because food companies find them easy to use and cheap to produce. They also last a long time and can give food a nice taste. As trans fats can be used many times in commercial friers they are commonly used in fast food outlets and restaurants. Several cities around the world are trying to stop outlets from using trans fats.
Where are trans fats commonly found?
- Fried foods, such as French fries
- Doughnuts
- Pies, pastries, biscuits, pizza dough, cookies, crackers, stick margarines, shortenings, and many other baked foods
If the nutritional labeling includes partially hydrogenated oils, it means that food has trans fats. The American Heart Association says your consumption of trans fats should not exceed 1% of your total calorie intake.
The Atkins diet says that saturated fat is overrated as a bad fat. The Atkins diet adds that trans fats are much more important in developing vascular disease.
How much fat should I eat?
According to the Dietary Guidelines for American 2005, the following percentages are recommended:- Children aged 2 to 3 - total fat limited to 30%-35% of total calorie intake
- Children aged 4 to 18 - total fat limited to 25%-35% of total calorie intake
- Adults aged 19 and older - total fat limited to 20%-35% of total calorie intake
Over the last 50 years the percentage of people in most countries who are overweight has increased significantly. This is due to many factors, but NOT because people's fat intake has increased. Over the last five decades the consumption of carbohydrates as a percentage of total calorie consumption has increased dramatically - not fat consumption. Fat consumption does not make your body produce more insulin; carbohydrates do that. The more insulin your produce the more energy your body will store away as fat. When deciding how much fat to consume, remember that the answer is not simple - there are many types of fats, carbohydrates and proteins.
Sources: National Health Service (NHS), UK, The Mayo Clinic, Wikipedia, HHS (Department of Health and Human Services USA), NIH (National Institutes of Health, USA), American Heart Association
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