A Dietitian Debunks 5 of the Biggest Food Myths

Nutrition can be a confusing landscape to navigate. There is SO much nutrition information out there on the internet, social media, in the lunchroom, at functions and so on. Much of the information you may hear is conflicting, which can make it tricky to know what to believe.

Below, I debunk some of the biggest food myths out there with an evidence-based approach.

Myth #1: Carbs cause weight gain

Carbohydrates in isolation do not cause weight gain, in fact, they can be very beneficial to assist with weight management. Carbs are an important fuel source. They help sustain energy levels and concentration, as well as improve both mental and physical performance.  

Weight gain results from excess energy intake, not specifically from carbohydrates. If consuming excess carbohydrates, which results in an excess in energy intake, then you will gain weight – but this is due to the energy surplus, not the carbohydrate. You may notice the number on the scale increase after increasing carb intake/having a higher carb meal the night before – but this is due to fluid retention, not true weight gain.

Myth #2: Ketogenic diets makes you burn fat more efficiently

A ketogenic diet is a diet that is very high in fat and very low in carbohydrates. There are a few varieties of the diet – but a traditional ketogenic diet is 70% fat, 20% protein and 10% carbohydrate.  It’s most commonly used by individuals for weight loss, due to the misconception that you 'become more efficient at burning fat as fuel'. Ketogenic diets can help with weight loss, due to suppressing appetite and therefore consuming fewer calories, versus actually using fat as fuel.

The evidence shows a keto diet is not superior to a high-carb diet for weight loss when calories are kept the same. It’s also unsustainable for most people, and lacks a lot of key nutrients. Due to its low fibre content and typically higher saturated fat content, ketogenic diets are also one of the worst diets when it comes to gut health.

Myth #3: Gluten is bad

One of the most common food myths is that gluten is terrible, and everyone should be avoiding it like the plague. Gluten is a protein found naturally in products containing wheat, rye, oats and barley. Gluten only triggers an inflammatory response in individuals with coeliac disease. For most of us, gluten-containing foods are actually anti-inflammatory due to the prebiotic fibre content of the foods it is typically found in.  

With the exception of those with coeliac disease, most individuals who find they don’t tolerate gluten are actually intolerant to wheat fructans. An easy way to determine if it’s gluten or wheat fructan causing issues is to trial foods that are low in wheat fructans but contain gluten such as rolled oats or sourdough bread.

Myth #4: Low-fat is better than full-fat dairy

There is a lot of noise out there around low-fat vs full-fat dairy. When it comes to the sugar content of milk, 250ml skim milk only contains 0.5g more sugar compared to 250ml full cream milk – which is incredibly insignificant. For something like yoghurt, there certainly are low-fat yoghurts which have a higher sugar content to compensate for flavour. However, there are also plenty of great low-fat yoghurts which are low in sugar. Keep in mind, much of the sugar content in dairy comes from the naturally-occurring sugar lactose.  

When it comes to which is better – it depends on family history of heart disease and personal preference. The guidelines recommend choosing low-fat dairy if you have a history of heart disease or high cholesterol, or a family history of these. If you have no personal or family history of heart disease/high cholesterol, then either is fine depending on personal preference!

Myth  #5 Dairy and acne

On the topic of dairy – I get asked all the time whether dairy actually causes/exacerbates acne. This one does have some truth to it in some scenarios. Dairy can exacerbate acne for some individuals. This is thought to be due to the whey protein, rather than the lactose content. If you suspect dairy may be triggering your acne, it's important to seek guidance from an experienced dietitian to ensure an elimination trial is done correctly with key nutrients being replaced from other sources.