Should you eat a high-fat breakfast to boost metabolism?

Nutrition tips: should you really eat a high-fat breakfast to boost metabolism?

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Most of the typical breakfast foods are high in carbohydrates. Toasts, cereals, granola bars are found in every work canteen and home kitchen cupboard. So why do fitness professionals claim that we should only be eating fat and protein before midday?

Being a fitness editor, I’ve done my fair share of challenges and transformations. Some were really interesting and have gone on to inform how I eat and move today, and others were downright dangerous. One thing that unites them all, however, is what I was told to have for breakfast. Every PT I’ve worked under has stressed the importance of eating a high-fat and protein, low carb start to the day.

On the days when I do eat breakfast (often I try to practise intermittent fasting until lunchtime), that’s seen me switch my bowls of overnight oats for chia puddings, yoghurt and smoothies. The only time I tend to have carbs in the morning is when I’m preparing to go for a long run or I’ve cycled into the office after a workout. 

But given that traditional breakfast foods are carb-rich (think toast, cereal, porridge), is the high-fat breakfast just another fitness fad designed to further destroy our relationship with food, or is there any truth behind being carb-free before midday?

Do high-fat breakfasts really reduce inflammation?

I was always told that a high-fat breakfast would promote ketosis in the body, forcing it to rely on its own energy supply to function. Many believe that sugar is an inflammatory, so swerving carbs (which get broken down into glucose) early in the morning is not only supposed to promote better metabolic health but also reduce stress on the system.

According to a 2018 study published in The Journal of Nutrition, eating a high-fat, lower-carbohydrate breakfast may reduce the risk of metabolic disease like type 2 diabetes.  It’s worth saying, however, that the study only looked at the effects on 29 people within a 24-hour window. In another piece of research, this time published in the International Journal of Food Sciences and Nutrition, scientists from the University of Leeds examined the role of high-carb and high-fat breakfasts on feelings of fullness and alertness, and subsequent food intake.

The most filling meal was the high-fibre, carbohydrate-rich breakfast (like oats) which was associated with less food intake during the morning and at lunch. Hunger returned more slowly compared to those who ate a low-fibre, high-carb meal (so think pastries). The high-fat meals may have tasted nicer but were much less satiating than either of the carb-rich meals and actually led to more food being eaten during the course of the morning. 

By the end of the day, participants who ate the high-fat breakfasts had consumed significantly more food and fat than the others, with the high-carb, high-fibre breakfast being associated with the greatest alertness during the morning and fullness. That led researchers to conclude low-GI carbohydrate-rich meals may be the best options if you want to stay wide eyed and full till lunch. 

Not all fat is ‘good’ and carbs ‘bad’

That study tallies with nutritionist Kimberley Neve’s thoughts on keto-esque meals. She says it’s not as simple as saying ‘fats = good, carbs = bad’. She explains that it depends what kinds of fats we’re eating (mono or poly-unsaturated like avocado, nuts and seeds over butter and meat), as well as the types of carbs. While white bread and pastries aren’t the best breakfast when it comes to energy and satiation, she says that slow-digesting carbs like oats and wholegrains are great.

“I’d argue that a high protein breakfast is helpful for keeping you going all morning (eggs, nuts, Greek yoghurt). A low-carb breakfast might be helpful for people managing type 2 diabetes – otherwise, it’s not necessary as fibre can make you feel fuller for longer too,” she tells Stylist.

High-fat breakfasts are a part of the keto lifestyle

This idea of the whole fat diet comes from the keto community. The low (or often no) carb philosophy has thousands of devout followers who claim that going keto has transformed their body shape, energy levels and capacity for thinking clearly. But there are plenty of experts who warn against waging a war on carbs.

“There is limited long-term research into the effects of following a keto diet, so although it works for some people short-term, it’s so restrictive that it’s not a diet people can follow forever,” Neve explains. Given that we want to find a way of eating that we can stick to for life, keto isn’t going to work for the majority. She also points out that it tends to be incredibly low in fibre, which has huge health implications. “Even if the fat intake is mostly mono- and poly-unsaturated fats, it’s not as healthy as it is often made out to be. It’s just another fad diet that creates rules around eating that are not necessary for health, strength or, if desired, weight loss.”

Matching your breakfast to your activity levels

In an ideal world, you’d want your diet to reflect the activity you do. For high-intensity exercise like running, you need to eat good quality carbs, but that’s not to say that we can’t enjoy less hard-working foods like croissants, granolas and sugary cereal bars. Neve simply says having an awareness of sugar levels is good: “At any point of day, this will lead to a quick release of energy and then feeling tired and hungry later. If the toast is whole grain, then there’s really no issue there. If it’s a weekend or ‘sometimes’ breakfast, then again, no issue.”

So, what would a nutritionist eat for breakfast? Neve says the ‘ideal’ breakfast has at least one fruit or veg, a high fibre food and something that contains a lot of protein. That might be:

  • Two eggs on whole grain toast with spinach, cherry tomatoes, mushrooms and/or avocado
  • Greek yoghurt with fruit and a nut butter or mixed nuts/ seeds
  • Porridge made with cow’s milk or soya milk (most other plant milks are very low in protein) and fruit

Fruit for breakfast: detoxifying properties?

Fruit is another contentious breakfast food. At one particular gym, I was told that you should always break your fast with fruit in order to neutralise any toxins built up overnight. Given that vitamin C is a powerful antioxidant, it doesn’t seem wholly unbelievable that eating citrus and berries first thing may have some real health benefits.

But again, Neve is quick to throw water over that theory: “There’s no such thing as magical anti-toxin powers I’m afraid! And no, we do not build up ‘toxins’ overnight - if anything, sleep is when the body recuperates. Any toxins in our body are very effectively and consistently dealt with by (mostly) our liver and kidneys.”

There is, however, a kernel of truth behind the idea of fruit helping to detoxify the system (“There’s always something influencers and dubious PTs will hold onto to make claims sound legitimate!” Neve says. “Fruits (and vegetables) have antioxidants, which can help to mitigate the negative effect of free radicals in our body, which can cause harm. It doesn’t matter when you eat them – research into nutrition and circadian rhythms, etc is ongoing – but there’s not enough to make any claims for anything yet.”

For more nutrition tips, check out the rest of the Strong Women Training Club archive. 

Images: Getty

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Miranda Larbi

Miranda Larbi is the editor of Strong Women and Strong Women Training Club. A qualified personal trainer and vegan runner, she can usually be found training for the next marathon, seeking out vegan treats or cycling across London on a pond-green Tokyo bike.

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