Skip to: Main Navigation | Main Content
or try the A-Z Library
Confused about whether or not you're supposed to eat less fat? No wonder. The 'fat is bad' message of the 1980s was nice and simple, but it didn't tell the full story.
For years, fat was public enemy number one. If there was one health message that was drummed into us, it was to cut fat in our diet.
Why? Because fat makes you fat. It clogs up your blood vessels, placing an extra load on your heart. And it increases your risk of diseases like bowel and breast cancer.
Only recently have we discovered the picture is more complex. Experts now emphasise that not all fats are equal. Its role in cancer risk is unclear. And for many of us, a little fat on the plate may be just what the doctor ordered.
One reason to watch your fat intake is that fat is fattening. Gram for gram, it contains more than twice as much energy kilojoules than either protein or carbohydrates. So of all the food types, fat has the greatest potential not to be fully burned up and therefore to increase our body fat.
To make matters worse, many foods that are high in fat (think sausages, cream, pastry and cakes) are low in fibre the plant material that helps us feel full and limits how much we eat.
We need some fat it makes up part of our brains, it protects some of our joints and it provides reserves for when we're sick but it slips down so effortlessly, it's easy to overindulge.
For every 10 kilograms of extra body fat, there are some 29 kilometres of extra blood vessels through which blood must be pumped. That's a big load on our hearts.
Extra body fat also increases wear and tear on our joints and can increase our odds of gallstones, diabetes and high blood pressure.
What's more, certain foods high in fat can harm our hearts in other ways. They encourage our liver to make more cholesterol, which chokes our arteries, causing heart attacks and strokes.
Over the past two decades or so, obesity has reached epidemic proportions in many Western countries. We might have heard the 'fat is bad' message, but we're still stacking on the kilos.
And what's becoming increasingly clear is that not all fats are equal.
Some fats are inherently more harmful to our health than others.
Saturated fats found in a wide range of foods including fatty meats, full cream dairy products, pastries and cakes raise our risk of heart attacks and strokes by increasing blood cholesterol levels (for more details, see The cholesterol story below).
Trans fats are even more potent than saturated fats in raising bad blood cholesterol. Found in many snack foods, processed foods, commercially prepared fried foods and some margarines, these man-made fats are produced by heating liquid vegetable oils in the presence of hydrogen (a process known as hydrogenation).
Unsaturated fats, on the other hand, are 'good' fats and can actually help unclog blood vessels blocked by cholesterol. Unsaturated fats include the mono-unsaturates found in olive oil, canola, and avocados, and two types of polyunsaturated fats: omega-6 (including safflower and sunflower oils) and omega-3 (found in fish, some plants such as spinach, nuts and seeds). Most Western diets are lower in omega-3 than omega-6, so focusing on boosting omega-3 fats is especially important.
Good and bad cholesterol. Just as there are good and bad fats, there are also good and bad types of cholesterol. Bad cholesterol, known as LDL cholesterol, tends to stick to artery walls, making it harder for the blood to get through. Good cholesterol, or HDL cholesterol, cleans up bad cholesterol and takes it back to the liver.
How good and bad fats affect good and bad cholesterol. Saturated fat raises both good HDL and bad LDL but the net effect is negative. Trans fats raise bad LDL and lower good HDL, so are especially harmful. Unsaturated fats, in contrast, pack a double 'good' whammy: not only do they lower bad LDL, but they also raise good HDL.
Foods and cholesterol. Eating cholesterol in foods has a much smaller influence on blood cholesterol levels than the mix of fats in the diet. Cutting back on foods containing saturated and trans fats is a more useful way to reduce blood cholesterol.
More information: Cholesterol fact file
We tend to make a number of mistakes when we try to cut down the total fat in our diets.
Mistake 1: We cut the good fats
When people think 'low-fat' the first to go tend to be unsaturated oils used for frying foods and in salad dressings, so our blood vessels miss out on their beneficial effects.
Foods like avocados and nuts are also important sources of other nutrients, along with the good fats, so avoiding them can leave us deficient in substances our bodies actually need.
There's even evidence that cooking vegetables in oil enhances the absorption of lycopene, the red pigment in tomatoes that helps fight cancer and heart disease. So don't shy away from using healthy oils in moderation.
Mistake 2: We cut the wrong bad fats
Even when people understand the need to cut saturated fats, they tend to steer clear of meat and dairy products. Although these foods contain saturated fats, they're also good sources of protein and vitamins, so it's better to eat reduced-fat varieties rather than cutting them out altogether. That means opting for low-fat rather than full-fat milk, skinless chicken, and lean cuts of meat rather than meat marbled with white fat or with a thick strip of fat down the side.
Mistake 3: We overlook 'hidden' fats
The fats we should limit most are the saturated fats hidden in processed foods like pastries, snack bars, and crumbed and coated foods as these often contain few other useful nutrients.
Trans fats are also easy to overlook. Australian manufacturers don't have to include trans fat on food labels unless they make a claim about cholesterol or unsaturated fats, while they do have to list levels of total and saturated fats.
Mistake 4: We're seduced by 'low-fat' labels
Food marketed as 'low-fat' can be an important part of a healthy diet but over-relying on such claims can be dangerous. Having cut the fat, many manufacturers make up for the loss of taste and mouth-feel of foods by increasing sugar or refined starches.
There are low-fat yoghurts, for instance, with as many kilojoules as the original high-fat product they're trying to replace. But there are brands of low-fat yoghurt with moderate amounts of sugar. Compare labels before you buy.
The other problem with 'low-fat' processed foods, is that we tend to eat more of them. Who hasn't gone for an extra scoop of ice-cream, thinking it's 'low-fat' so it must be OK?
If a food doesn't provide many important nutrients anyway, low-fat claims can lull us into a false sense of security suggesting 'fat is all that matters'. So we believe we're merely having a guilt-free indulgence when we eat half a pack of 'no-fat' jelly beans when we could be getting the same kilojoules along with a host of valuable nutrients in, say, a chicken sandwich.
What's in a name?
Most foods contain a mixture of saturated, mono-unsaturated or polyunsaturated fats but are named after the predominant type of fat. Olive oil is a mono-unsaturated oil because that makes up 72 per cent of it. But it also contains 13 per cent polyunsaturates and 12 per cent saturates.
Animal or vegetable?
Saturated fats were once thought to occur mainly in animal fats, but today, 40 per cent of our saturated fat intake comes from vegetable oils. That's because some vegetable oils coconut, palm kernel, and palm are naturally high in saturated fats. And manufactured foods commonly use vegetable oils that have been altered by the process of hydrogenation to improve their consistency. Not only does hydrogenation produce undesirable 'trans fats' but it also increases the saturated fat content of the vegetable oil.
What can you trust?
If you're buying vegetable oil in a bottle and it's a liquid, you can be sure it's a 'good' fat. But in an ingredient listing, vegetable oil could refer to bad fats like coconut and palm kernel oil, or to trans fats. Imported foods may list trans fats, or they may also be called 'partially hydrogenated' oils.
So if good fats are good, does that mean we should we eat as much of them as we want? No. Fat is not all bad, but overeating is. Kilojoules still count. Nuts like almonds contain good fat, but it's easy to eat too many of them.
And while being a little overweight may not be as hazardous to health as previously thought so long as you're physically active the truth is most of us aren't active enough. It's much easier to gain weight than to lose it, so a few extra kilos could be the start of a slippery slope to obesity, which is definitely a health hazard.
For years, health authorities have recommended we eat less fat (they now emphasise less saturated and trans fat) along with more vegetables, fruit and products made from grains. Yet the obesity epidemic has worsened. It's tempting to conclude that the current dietary advice is wrong and eating less fat doesn't work to help us lose weight.
The high profile of the Atkins and CSIRO Total Wellbeing Diets has fuelled our doubts, leaving many of us with the impression the amount of protein versus carbohydrate in the diet might be the real 'secret' to staying slim.
Similarly, the discovery of the Glycaemic Index (GI) of foods a measure of how fast the carbohydrate in a food is broken down to form glucose in our blood has highlighted that choosing 'slow' or low-GI carbs over 'fast' or high-GI ones plays a role in controlling appetite. Many of us are left wondering if that's the 'answer' to our fat woes.
While debate over these issues is valid, it's easy to be distracted from a simple truth: you gain weight if you consume more kilojoules than you burn up.
Research shows most of us don't follow the current national dietary guidelines even though there's good evidence they work. Overall fat consumption in the Australian population remains high and we're eating less fruit, vegetables and grains.
For a healthy diet:
1. Cut your saturated fat intake. Opt for low-fat dairy products and choose lean cuts of meat or chicken, trimming off all visible excess fat. Avoid processed meats like sausages and salami. Try to minimise the cakes, pastries, biscuits, and snack bars you eat.
2. Keep the healthy fats in. When you're keeping fat to low levels, make sure the fats you do choose are 'good fats'. Aim to eat fish at least twice a week (fresh or canned). Cook with healthy oils (olive oil, canola, soybean, safflower, sunflower). Add nuts like walnuts and almonds to stir-fries and salads.
3. Beware of foods marketed as 'low-fat'. Don't assume they're low in kilojoules because they're labelled 'low-fat'. Don't eat more than you normally would just because they're 'low-fat'. Think twice about eating 'low-fat' food if it's also low in the nutrients your body needs.
If you're trying to lose weight:
1. Keep your intake of fat below about 40 grams a day, possibly reducing this to 30 grams if you're small and inactive. (As a guide, one tablespoon of oil of any kind contains 20 grams of fat. So using this amount in salad dressings or cooking leaves only 10 to 20 grams from other sources.)
2. Remember, fats aren't everything. Keep your overall kilojoule intake moderate to low by also decreasing alcohol, sugar and refined starches. The easiest way to do this is to eat a diet rich in fruit, vegetables and wholegrains.
For years, there has been a suggestion total dietary fat might be linked to an increased risk of getting a number of cancers, including lung, bowel, rectum, prostate and breast. But teasing out the effect of one component of a diet on a disease that develops over many years is extremely difficult.
A major study published recently, however, showed reducing dietary fat makes no difference to the risk of either bowel or breast cancer. The effect may depend on how much saturated versus unsaturated fat is eaten, or whether or not a person's risk of getting cancer is already increased for some reason. For instance, one important study of women with early-stage breast cancer who were presumably at greater risk of future cancers than other women showed that a low-fat diet reduced the odds of a recurrence by 20 per cent.
The Cancer Council of Australia points out that high fat consumption probably contributes to obesity, and obesity is a risk factor for several cancers. So reducing the fat in your diet may do good and is certainly unlikely to do harm. Since we're interested in staying alive and healthy not just cancer free it makes sense to follow general health guidelines and cut saturated fats in preference to unsaturated fats.