Fats & Weight Loss
Fats are an essential part of our diet, largely used to provide energy and support growth. Fats are the most concentrated source of energy available to our body. However, the average Australian eats far more fat than required for good health, further increasing the difficulty of weight loss.
The main problem with consuming excess dietary fat is the effect on weight gain. Fat has double the amount of calories compared to carbohydrate and protein, therefore a reduction in fat intake is a priority for reducing total calorie intake. Also, a high fat intake, independent of weight, has been linked to health conditions such as high blood cholesterol, coronary heart disease, and colon cancer.
To understand this further we need to look at the different types of fat are and how they are used in our body. Sustainability is a major factor and a healthy food intake should incorporate changes that are long-term.
Many popular 'diets' are difficult to adhere to and are not enjoyable. Eating should be pleasurable and it is important to consume a wide variety of foods for enjoyment and nutritional adequacy.
Types of Fats
Saturated fat is found mainly in animal-derived food sources such as dairy products and meat. Two plant sources of saturated fat are coconut and palm oil and these are often used in processed foods such as biscuits, chips and snack foods. Saturated fats tend to raise LDL-cholesterol in the blood and can increase the risk of heart disease, obesity, diabetes and certain cancers. Saturated fat is a major dietary determinant of blood cholesterol levels (NHF, 2007).
Trans-fatty acids are unsaturated fatty acids found naturally (in small amounts) in animal-derived foods and are also formed during hydrogenation of vegetable oils eg. margarine. Trans fatty acids tend to increase bad (LDL) cholesterol levels and intake should be limited (DAA, 2006).
Monunsaturated fats are found in vegetable oils (particularly canola, olive, Sunola), some margarines, avocados, most nuts, lean red meat, chicken, eggs and fish. Mono-unsaturated fats have been shown to produce a lower LDL to HDL ratio, beneficial for cardiovascular health (Anderson,NHF, 2001).
Polyunsaturated fats can be divided into omega-3 and omega-6 fatty acids:
The major source of omega-3 fatty acids is oily fish and seafood, with smaller amounts found in canola, linseed (flaxseed), walnut and soybean oils. Omega-3 fatty acids have a range of functions in the body as they are incorporated into every cell, tissue and organ.
The main sources of omega-6 fatty acids are vegetable oils, grains, nuts, seeds and wheatgerm. They are chemically similar to omega-3's, however they act differently in the body and if intake is too high this may reduce the beneficial effects of omega-3 fatty acids.
The right balance of omega-6 to omega-3 fatty acids is essential for optimal health and the intake of polyunsaturated fats should be in a ratio of about 5:1 of omega-6 to omega-3. Most Australians have a ratio much higher than this, due to inadequate intake of omega-3 fatty acids. Research shows that consuming at least two fish meals per week is protective against coronary death.
Current research indicates that replacing saturated fat with polyunsaturated fats reduces coronary heart disease risk (Anderson,NHF, 2001).
Why is low fat eating important?
Fat contains twice as many kilojoules as carbohydrates as protein, therefore it is easy to overconsume, and this may contribute to weight gain.
Dietary fat is easily deposited as fat within the body, however it is more difficult for the body to convert carbohydrates to body fat.
Unsaturated fats are a better health choice, but remember that all types of fat contain the same amount of kilojoules and make a similar contribution to body fat levels.
The breakdown, or oxidation, of fat in the body leads to the production of free radicals that can damage body cells. Anti-oxidants help to swallow up damaging free radicals, which is why fruit, vegetables and wholegrains are so important due to their high antioxidant content.
NO MORE THAN 30% OF TOTAL ENERGY INTAKE SHOULD COME FROM FAT, WITH LESS THAN 8% TOTAL ENERGY INTAKE SATURATED FAT.
Females: 40-50g fat per day
Males: 60-70g fat per day
Some people may require more or less than these amounts depending on factors such as age and activity levels.