Fats and Oils
Over the last 50 years we have been told to eat “low fat” or “no fat” and fat has been demonised. However, while the low fat food industry has profited, obesity rates have not fallen. Some believe that our obsession with low fat food has actually contributed to obesity.
The truth is, fat has a crucial role in your body and performs important tasks. It is a form of energy storage. Very importantly, it transports the fat soluble vitamins A, D, E and K. Fat forms part of the membrane of every cell in your body and it protects vital organs as well as helping the body regulate temperature.
Because they are digested slowly they help to make you feel full and they also slow the digestion of carbohydrates which helps to reduce insulin spikes and contributes to a steady supply of energy. They also give flavour and texture to food. When they remove fat from the low fat foods they have to replace flavour in some way so these types of foods tend to be much higher in sugars. Low and no fat foods are also less satisfying which can lead to snacking and extra calorie intake – this is one hypothesis of why low fat foods have had no impact on obesity rates.
As a general guide around 20-25% of your daily calorie intake should come from fats with a maximum of 10% coming from saturated fats.
Your daily calorie intake for your weight, activity level etc is 1800 calories a day. That means 450 calories should come from fat. There are 9 calories in 1g of fat. That means your daily fat intake should be 50g (450 calories divided by) and no more than 5g (10%) should be saturated.
Good Fat Bad Fat
So, it is important to remember that not all fat is your enemy. There are “good fats” and “bad fats”.
Structure of Fats
Fats are made up of chains of carbon atoms with hydrogen atoms attached so this is why you hear the terms short chain fatty acids, medium chain and long chain. It simply refers to a property of their structure.
You will also be familiar with the terms “saturated fat” and “unsaturated fat”. This simply refers to a chemical property of the fat. A saturated fat has all its possible hydrogen bonds occupied whereas with an unsaturated fat one or more of the possible hydrogen bonds are unoccupied. When only one hydrogen bond is empty the fat is called monounsaturated (mono = 1), when more than one bond is empty the fat is called polyunsaturated (poly = many).
All of these structural properties affect how the fat looks and behaves as well as how easily it can become rancid.
Saturated fats include animal fats, palm oil and coconut oil. They remain solid at room temperature. Some of them are associated with raising “bad” LDL cholesterol and they are linked with increased cardiovascular disease risk. Saturated fats are more stable which means they will react to light, heat and oxygen less.
Coconut oil is a special case – although it is a saturated fat, its chain structure is different to animal fats and it is suggested that pure coconut oil (not refined or hydrogenated) has many health benefits.
Monounsaturated fats include avocado, canola and olive. They are liquid at room temperature but can start to
solidify at colder temperatures. They are associated with raising your “good” HDL cholesterol. Most canola oil is now GM so it is important to use organic canola oil. If used for cooking olive oil is only suitable for low temperatures.
Polyunsaturated fats include corn, safflower and sunflower oil. They are liquid at room temperature and will remain liquid at colder temperatures. Some studies suggest an association with a higher cancer risk but also that they help prevent cardiovascular disease. Again, with corn, it is more likely to be GM so it is important to source organic corn oil if you want to use it. Corn oil does tend to be more stable at higher heats.
With both mono and polyunsaturated fats they are less stable and can easily be damaged by light, heat and oxygen. When they oxidise the molecular structure changes and they become rancid. Eating rancid fats can cause cell damage in the body. Commercial salad dressings often contain rancid fats and the seasonings mask the odour. One good habit to form is always making your own salad dressings – its quick, easy and you control the ingredients.
You might like some of these easy salad dressings.
Everybody has heard of hydrogenated fats but not everybody really understands what they are. Basically, hydrogenation is a process that food manufacturers use to extend the shelf life of their product. They can take a cheaper oil and force hydrogen atoms through it to create a fat that more resembles a saturated fat but during the hydrogenation process molecular structures change and form harmful “trans fats”.
Try to avoid all products that contain hydrogenated or partially hydrogenated oils. In Canada, labelling laws allow a product to be labelled non-hydrogenated (or trans fat free) even if it contains partially hydrogenated oils if they form less than 9% of the product. Always read the ingredient list as labels can be misleading sometimes.
Omega Essential Fatty Acids
The final category of fats are what we refer to as the omega essential fatty acids. We have all heard of omega-3, omega-6 and omega-9.
Basically the body can make most of the fats it needs by altering fatty acid chain lengths itself. However, there are two fats it is unable to make for itself and must obtain from the diet – which is why they are termed “essential”. These are omega-3 (alpha linolenic acid) and omega-6 (linoleic acid).
The best sources of omega-3 are coldwater fish such as herring, mackerel, salmon and sardines but you can also use fish oil capsules. Omega-3 is also found in flaxseeds and flaxseed oil as well as hemp seeds and hemp seed oil. Omega-6 is found in most plant oils, oat germ, wheatgerm and rice bran. They typical standard North American diet provides too much omega-6 but hardly any omega-3.
Suggestions for Changes
- choose lean cuts of meat and preferably organic or grass fed
- include cold water fish at least twice a week
- use flaxseed, flaxseed oil, hemp seed and hemp seed oil
- use 1 tablespoon of cold pressed extra virigin olive oil on salads and vegetables each day as your source of monounsaturated fats
- avoid hydrogenated fat in commerical cakes, pies, cookies, muffins and lots of other processed foods
- avoid potentially rancid fats in commercial salad dressings
Special Note for Seeds
If you purchase seeds to include in your diet such as flax, hemp, chia, sunflower and pumpkin remember that the delicate fats can be easily damaged and lose their health benefits so keep your seeds in the fridge. You can even keep them in the freezer quite safely. Keep flaxseeds whole until you are ready to use them and then grind them just before use in a small coffee grinder. Don’t buy ready ground flaxseed as you don’t know how long it has been since it was ground as the delicate fats could have been damaged.