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.
What are fats?
Olive oil in water. Fats don't dissolve in water. They are insoluble in water.
Some fats are liquid at room temperature while others are solid. We refer to those which are liquid at ambient (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.
- Animal fats - butter, lard, cream, fat in (and on) meats.
- Vegetable fats - olive oil, peanut oil, flax seed oil, corn oil.
Lipids are an important part of the diet of all humans and many types of animals. Fat is stored in the body for many reasons.
When too much fat is accumulated we become overweight or obese. Eating too much fat can make us overweight, but so can too much carbohydrate or protein. In fact, the over-consumption of fast carbohydrates is more closely linked to overweight and obesity than fat consumption.
Recent developments on the ways we store fat from MNT news
Exercise causes genetic changes in how we store fat. When we exercise regularly, the epigenetic pattern of genes that influence how our bodies store fat changes, researchers from Lund University, Sweden, explained in the journal PLoS Genetics.1
Different types of fats
There are several different types of fats and we'll take a look at these below.
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, says the American Heart Association8.
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.
Avocados are a good source of monounsaturated fats.
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.
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 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 hydrogenated 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 Association2 says your consumption of trans fats should not exceed 1% of your total calorie intake.
How much fat should I eat per day?
According to the Dietary Guidelines for American 20054, 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
Dr. Barry Sears, who created the Zone Diet, says an average adult should consume 30% fat, 30% protein and 40% carbohydrate5 - he stresses that the types of fats are important, favoring the omega-3 oils and vegetable oils.
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 you 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.
Recent developments on fats from MNT news
Planned high-fat diet can help weight loss. A well-organized high-fat diet can spark a unique metabolism change where ingested fats are stored and used for energy when no food is available, researchers from the Hebrew University of Jerusalem reported in The FASEB Journal.6
Estrogen affects where a woman's fat is stored
Scientists form East Carolina University found that where a woman's fat is stored in her body is influenced by estrogen, a female sex hormone.7
This may explain why most adult females have a "pear" shape compared to men.The study authors wrote "Our results indicate that the influence of E2 (estrogen) is dependent on the adipose tissue (loose connecting tissue) depot of interest as well as the specific regulatory mechanism targeted. The importance of understanding estrogen action in adipose tissue is underscored by the fact that adipose tissue is an estrogen-producing organ, particularly in postmenopausal women, where adipose tissue is the major site of estrogen production."
The researchers say their findings may one day help us understand why postmenopausal women tend to accumulate abdominal fat.
The relationship between estrogen and the breakdown of fat is what gives premenopausal women their "pear" shape.
Video - What is fat?
In this TED video, George Zaidan gives a lesson on the different types of fats.