There's been so much noise around fat this year, especially the idea that saturated fat is good for us - and if only we'd ignored the advice to avoid it we'd be leaner and healthier. But this my-fat-is-better-than-your-fat debate overshadows another big fat issue: the role that a better balance of fats has on our health and maybe our waistlines.
What's really making us fat and sick is a skewed mix of two polyunsaturated fats in our diet caused by too few omega-3 fats from fish, nuts and leafy greens and too much omega-6 fat from processed food, vegetable oils such as sunflower seed oil, and meat from intensively farmed animals fed on grains, not grass, says US scientist Dr Artemis Simopoulos. We do need some omega-6 fat, but too much can increase low level inflammation in the body, promoting obesity and insulin resistance, she argues in the journal Open Heart
For good health we need equal amounts of omega-3 and omega-6 fats – not the current ratio of around 16 to 1 one in favour of omega-6 fats, says Simopoulos from the Centre for Genetics, Nutrition and Health in Washington.
The idea that the ratio of these fats matters – and what the best ratio might be – is controversial – but there's no denying that we need more omega-3 fats says Dr Catherine Itsiopoulos, Professor of Nutrition and Dietetics at Melbourne's La Trobe University.
"Omega-6 fats are pro-inflammatory and omega-3 fats are anti-inflammatory so it makes sense that we need more omega 3 fats from fish, nuts and greens like broccoli and rocket," she says, adding that there's some evidence that omega 3 fats are important for weight loss.
"A study looking at the effect of different diets on type 2 diabetes found that a Mediterranean diet based on more plant foods and fish was rated best over all and was also the best for weight loss, along with a low carb diet," she says.
But we do know that 80 per cent of Australians aren't eating enough omega-3 fats for optimal health according to an analysis of the latest National Nutrition and Physical Activity Survey by Associate Professor Barbara Meyer from the University of Wollongong.
Although fish oil capsules might seem like an easy solution, studies have found more improvements with heart disease risk with fish rather than supplements, Itsiopoulos says.
"One reason may be that when you eat fish you're also not eating a burger or a fatty piece of meat. Replacing a meat meal with a fish meal isn't the same as continuing to eat a high meat diet and taking a fish oil supplement on the side – when you include fish you also improve the quality of your diet and decrease the amount of saturated fat you eat."
Swapping a burger for fish is one way of swinging the balance of fats towards more omega-3 fats. So is eating nuts every day, especially walnuts, and having a salad or vegetables with every main meal, which are other principles of a Mediterranean style diet. But Australians aren't doing well there either: only 16 per cent of us eat nuts and only 7 per cent of us eat enough vegetables.
The fat we cook with matters too. We've heard a lot about the supposed virtues of cooking with butter from the pro-saturated fat lobby, but Itsiopoulos puts extra virgin olive oil, a monounsaturated fat, ahead of both butter – and the polyunsaturated omega-6 fats often recommended for improving heart health.
"Although both polyunsaturated fats and monounsaturated fats can improve blood fats by dropping 'bad' LDL cholesterol and raising 'good' HDL cholesterol, monounsaturated fats have other benefits including improving appetite control and supporting weight management," she says. "Too many polyunsaturated omega-6 fats may also increase the oxidation of 'bad' LDL cholesterol which can cause inflammation in arteries, especially when there are insufficient omega-3 fats in the diet.
"But it's not just the fatty acids in extra virgin olive oil that are protective – it's also the antioxidants that are having an effect. Although a little butter is OK it doesn't have the benefit of antioxidants."