Nutritionist Sarah Di Lorenzo: Healthy fats — what’s actually best (and worst) for your body

Sadly fat has not had a great reputation in nutrition over the decades. It was demonised in the ‘90s, rehabilitated slowly in the 2010s.

After decades of low-fat this and keto that, the truth is genuinely really simple. Not all fats are created equal, and the type of fat you’re eating matters far more than the total amount on your plate.

Before we get into the good and the bad, it’s worth remembering why we need fat in the first place.

Fat isn’t optional it’s essential. It’s the building block of every cell membrane in your body, it’s what your brain is largely made of and what allows you to absorb the fat-soluble vitamins A, D, E and K.

Fat cushions your organs, insulates your nerves, and provides the raw material for your hormones, including your sex hormones and the anti-inflammatory compounds that keep your body running smoothly.

And here’s the piece most people miss: Fat is what keeps you genuinely full.

It’s the slowest macronutrient to digest, which is why a breakfast with avocado or a handful of nuts holds you for hours, while a low fat toast and jam morning leaves you hungry by 10am.

Fat triggers the satiety hormones that tell your brain the meal is over, stabilises blood sugar by slowing carbohydrate absorption, and takes the edge off cravings.

This is exactly why low-fat diets so often fail, they strip the fat out and you strip out the fullness, and your body will always look for that missing satisfaction somewhere, usually in sugar.

The best fats are unsaturated fats. They’re found in extra virgin olive oil, avocados, olives and nuts like almonds, cashews and hazelnuts.

Reliable studies consistently link them to healthier cholesterol and lower cardiovascular risk. Extra virgin olive oil, the backbone of the Mediterranean diet, remains one of the most evidence backed fats you can cook with and definitely one of the great pleasures of eating well.

Polyunsaturated fats may be even more protective, they reduce heart disease risk by around 19 per cent, roughly a 10 per cent drop for every 5 per cent of daily calories shifted across.

You’ll find these in walnuts, flaxseeds, chia seeds, sunflower seeds, pepitas, sesame seeds, tahini, pine nuts, Brazil nuts, edamame, tofu, and oily fish like salmon, sardines, mackerel, trout and tuna.

Omega-3s deserve their own spotlight. A large study of 45,000 adults found that people with high omega-3 levels in their blood and fat tissue had a 10 per cent lower risk of heart disease.

Best sources are oily fish such as salmon, sardines, mackerel, tuna plus walnuts and flaxseeds.

Trans fats are the worst fats as they raise your “bad” LDL cholesterol and simultaneously lower your protective HDL cholesterol.

Australia has largely phased them out of processed foods, but they can still hide in some baked goods, fried takeaway, margarine and imported products. Read the label and also look for anything listing “partially hydrogenated oil” .

Saturated fat is more nuanced than it’s often made out to be, but the evidence still leans toward moderation. Foods highest in saturated fat are animal fats like butter, and tropical oils such as coconut oil, cocoa butter and palm oil. But you also find saturated fat in dairy such as cheese, full fat milk and yoghurt.

These foods are very important in the diet as they are excellent sources of calcium, protein and in the case of yoghurt probiotics. Just stick to the daily recommended serving sizes.

I’ll be honest the science on saturated fat isn’t entirely closed. Some researchers argue not all saturated fats behave the same way, and lumping them together may oversimplify things.

It’s an active area of research. But mainstream cardiovascular guidance still favours swapping saturated fat for unsaturated sources.

You don’t need to fear fat at all, you need to choose well. Here’s how I put it to my patients :

• Cook with: extra virgin olive oil, avocado oil
• Eat more of: oily fish (2-3 times a week), nuts, seeds, avocado, olives
• Enjoy in moderation: butter, fatty red meat, coconut oil
• Avoid where possible: anything with trans fats also look for “partially hydrogenated oil” on the label

The most consistent message across all the research isn’t about cutting fat out. It’s about swapping the type. Replacing some saturated fats with unsaturated ones improves your blood lipids and reduces heart disease risk and doing that inside a whole-food eating pattern matters more than obsessing over any single nutrient.

Choose your fats well, enjoy them without guilt.