There's been a huge effort by health experts to reform our food supply and eating habits in light of the 'fat phobia' - a belief dietary fat is linked to chronic disease. But 50 years on, we're fatter, sicker and more poorly nourished.
The public's fear of fat is slowly melting away. However, it seems like most of the information is falling on deaf ears in the nutrition and public health community. Whether it's scepticism about drastically changing nutrition, or fear that what we've spent years telling the public may not be the complete story, the evidence that has re-emerged can't be ignored.
By no means are high-fat/low-carb diets the only answer to chronic diseases like obesity, coronary heart disease, stroke and diabetes. After all, humans have adapted to thrive on many diets - including the opposing high-carb/low-fat diet. What we haven't adapted to is the Western diet - rich in refined grains, low on fruit and veg, made in factories and eaten on the run.
If a high fat diet is a step away from such an insidious way of eating, then I think it's a step in the right direction.
I am not declaring allegiance to this school of thought, however it's important to consider the following fat facts to figure out how best to eat:
1. Saturated fat will cause cardiovascular disease
Actually it might not. A bombshell hit the nutrition world when a 2010 meta-analysis including 21 studies decided that saturated fat had no clear influence on coronary heart disease or stroke - the fat currently considered a big no-no came out unscathed! But you shouldn't go filling up on lard and lamb flaps just yet as it's likely to be more beneficial to replace saturated fat with mono- and polyunsaturated fats (mainly omega-3) and wholesome fruit, vegetables and wholegrains.
My suggestion: Eat less processed food containing the deathly combination of saturated fat, highly refined carbohydrate and sugar found in most wheat desserts like muffins, cakes and doughnuts. And don't stress about having whole foods with naturally occurring fat like meat, poultry, dairy, cream and coconut products when eaten as part of a healthy diet.
2. Trans fats should be avoided at all costs
This still can't be emphasised enough. The food industry shot themselves in the foot when developing hydrogenated vegetable oils to reduce our saturated fat intake. As a result, they created a new form of fat - trans fats - that not only reduce levels of good cholesterol, but also increase levels of bad cholesterol - a double banger! These fats are found in many processed baked goodies and some cheaper margarines.
My suggestion: Limit the pre-packed baked products, takeout and everything deep fried. Stick to foods that haven't be tampered with. In NZ, most products don't tell you the amount of trans fats they contain, so it's best to pay a little extra attention to get those higher quality margarines and if you'rec raving a treat, bake it yourself.
3. Eating fat will make you fat
No it won't. The door closed on the 'low fat diet is best for good health' hypothesis when a critical review in 2001 concluded eating different total amounts of fat did not dictate waist size or the presence of some chronic diseases. Instead, it suggested a diet high in refined carbohydrate and sugar may increase hunger and promote overeating - leading to weight gain. This may come as surprise to you, but not for the Inuits of the Arctic who get more than half their calories from fat - mainly in the form of omega-3 rich fish - and have some of the world's lowest rates of cardiovascular disease, which shifts the focus from how much fat to what type of fat we should eat for good health.
My suggestion: Eat fats as they're found in nature. My favourites are fatty salmon, olive oil, avocado, nuts, seeds and the occasional bit of butter. And limit fatty foods that are packaged or made by a machine - this means takeaways, baked goods and those deep-fried in hydrogenated plant oils.
4. Replacing fat with carbs is healthier
The debate of the last 50 years! To add to the murkiness, this is sometimes the case. The body has evolved to thrive on many forms of calories, but not those made in factories. The industrial food system has refined, processed and destroyed what grains and seeds once nourished us with. The bran and germ have been taken away to form a nutrition-less white dust lacking in the folate, omega-3, fibre and B vitamins. Or if you were to eat wholesome fruit and veg, then you'll also be getting the vitamins, minerals and fibre with your carbs.
My suggestion: Eating wholegrains, fruit and starchy vegetables like potato and kumara is healthy, as long as the amount you eat matches your energy requirements. But if you're gaining weight or eat most of your carbs from industrialised flour and sugar, then it's best to reconsider your dietary choices.
5. We should all eat more polyunsaturated fat
Yes we should, but what type? Omega-3 and Omega-6 polyunsaturated fatty acids are both essential to our diet because our body can't produce them. However, they work in different ways. Omega-3s play an important role in the development of our brain, refining our vision, improving cell permeability and utilising blood sugar. Whereas, Omega-6s are used in fat storage, maintaining sturdy cell membranes, blood clotting and inflammation. The two compete for space in the cell and at the moment, we have a chronic imbalance of too much omega-6 and too little omega-3. Consequently, our body's inflammation and clotting response is magnified - something those at risk of cardiovascular disease are trying to prevent.
My suggestion: To help reverse the imbalance, use olive oil over seed-based oils, avoid deep fried foods, eat more anti-inflammatory omega-3 rich fatty fish like salmon and green leafy vegetables like spinach, brussels sprouts and kale. If there's supplement I would opt for, it's fish oil - but always check with your doctor or dietitian before using these.
6. Margarine is plastic and butter is natural
Margarine is a highly processed food, but it's not a plastic. Marg is a great example of a product the food industry has manipulated over time to meet the demands of the public - less fat, lower saturated fat, higher polyunsaturated fat (unfortunately mainly omega-6) and a texture matching that of butter. Did you know it was once dyed pink to ensure people knew it was a butter imitation? On the other hand, butter is less processed, has some omega-3s and is high in saturated fat.
My suggestion: There's really no answer to which one you should spread on your bread. Though if you're cholesterol is high, I recommend you buy a plant sterol enriched marg.
In the end, scientific schools of thought are never easy to challenge, even when they begin to crack under emerging contradictory evidence. But by looking back to see if low fat nutrition recommendations have gone astray, experts can patch up and preserve our current knowledge for future nutrition and public health campaigns.