NUTRITION: Is Fat Making a Comeback?

Words: Zoe Wilson
Photos:  Mike Blewitt

Like fashion, nutrition trends come and go. For years the message was to avoid fat but recently it seems that fat is making a comeback. Let’s unpick this tricky, and often controversial, one.

Do we need fat? 

Fat is one of the main sources of energy for the body, along with carbohydrates and protein. However, there are more than double the kilojoules in a gram of fat compared to a gram of carbohydrate or protein. This is the main reason for the advice to cut back on fat when it comes to managing weight – if the aim is to reduce calorie intake, then reducing fat results in the biggest bang for your buck. 

There are different types of fats, too, and some are healthier than others. Unsaturated fats are an important part of a healthy diet as they provide essential fatty acids and help with the absorption of important fat-soluble vitamins. Fats to watch out for are saturated and trans fats. Despite some claims, research continues to show a diet high in saturated fat is linked with high levels of cholesterol in the blood, a risk factor for heart disease. Similarly, eating too much trans fat can increase levels of harmful LDL cholesterol in the blood and decrease beneficial HDL cholesterol, which can increase the risk of heart attack or stroke.

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All of this leads to the general advice to go for sources of fats like olive oil, nuts and seeds, and to avoid excessive amounts of foods such as meats, butter, baked goods and deep-fried foods. 

In terms of how much fat to eat, the Australian Dietary Guidelines suggest that the optimal range for all types of fat is around 20-35% of daily energy to reduce the risk for chronic diseases such as heart disease and diabetes. Eating a moderate amount of fat can also help you to feel fuller for longer which can actually reduce the amount eaten over the day and help with managing weight. 

What about fat for performance? 

There is much debate about the role of fat vs carbohydrates in terms of athletic performance. One camp swears a high-carbohydrate diet is a holy grail, another camp that a low-carb high-fat diet is best, and all the various iterations in between. 

The proponents of low-carb high-fat for endurance performance think like this: if you train without eating many carbohydrates, the body must turn to the next best fuel option – fat. As fat is so high in energy and fat storage is also almost unlimited (unlike carbs where the body can only store enough for about 24 hours), there is a much larger amount of fuel at your disposal, theoretically meaning a longer ride before running out of fuel. No wonder fat adaptation is an ongoing source of fascination!

The problem is, converting stored energy in fat to energy the muscles can use when riding is quite inefficient. Fat metabolism is a complicated process. Carbs on the other hand are much more easily accessible as they are stored in the muscles and can be pulled on quickly, particularly when exercising at high intensities. 

Can you get better at using fat for fuel? 

Lots of research has focused on this question in varying ways. And there are lots of different manipulations of carbohydrates and fat that have been studied which makes it difficult to compare. Take the more extreme approach – a ketogenic low-carb high-fat diet in which the diet is approximately 5% or less of energy from carbohydrates, 15-20% protein, and 70-80% fat. A summary published in the Journal of Physiology in 2020 concluded that eating a ketogenic low-carb high-fat diet, even for shorter periods of time (3-4 weeks and maybe as short as 5-10 days), does improve the body’s use of fat for fuel. 

However, the paper also warned research has consistently found that carbohydrates are still the preferred and most efficient source of fuel when oxygen is short. In other words, at a high intensity (think short, fast races or high-intensity efforts in an endurance race), carbohydrates are still crucial to performance, and following a ketogenic low-carb high-fat diet will likely hinder performance. So, the type of riding and racing an athlete does is an important consideration.

One more thing the author notes, too – research in this area shows a high variability from person to person with extremes at both ends of the performance scale so even if it sounds like a good idea, it may not work for you.

The bottom line

Eating some fat is important for general health so there is no need to avoid it and go low-fat. However, it’s best to choose unsaturated fats as these are better for reducing the risk of chronic disease. 

When it comes to performance on the bike, it is possible to improve the body’s use of fat for fuel by following a low-carb high-fat diet. However, that won’t necessarily lead to better results, particularly if high-intensity efforts are required during racing or group rides. And it pays to remember there is no one size fits all when it comes to diet in general so it may take some trial and error to land upon what works best. 

So, you do you. But do it with help. Speak to a Sports Dietitian and they will help figure out what is the best way of eating for your health, goals and performance on the bike.