A nutritionist’s review of the keto diet

Emma Brown - Nutritionist | 10 Jan, 2021

We understand that when it comes to losing weight, you have to find an approach that works for you. Whether this be tracking calories, eating fewer carbs, intermittent fasting or any other approach – here at Nutracheck we have you covered! Our app can be used to facilitate a wide range of dietary approaches, so you have complete flexibility to follow the one that's the best fit for your lifestyle. Throughout January I'm reviewing some popular weight loss approaches so you can decide which one may be right for you. Next up...

Keto and low carb diets

How does it work?

Keto – this is an extremely low carb diet. What characterises it as 'keto' rather than just 'low carb' is that it is high fat and moderate protein – whereas traditional low carb diets tend to be higher in protein. We must also reach 'ketosis' for us to be on a true 'keto' diet.

Ketosis occurs when the body starts to use fat and protein as fuel sources instead of glucose. Ketone bodies (or ketones) are produced from fatty acids in the liver when glucose levels are very low. They are then used to produce energy and become the primary source of fuel for the brain – since the brain can't use fat or protein as fuel.

Low carb – this diet approach on the other hand, requires a reduction in total carbohydrate intake, which is usually counterbalanced with an increased protein intake. Although there are no official guidelines on what constitutes a low carb diet, a carb intake of 30% your total daily calories or less can be considered a low carb diet.

Might it suit you?

Keto – this diet approach is very restrictive, so it may not suit everyone. If this is an approach you feel comfortable with, you may see favourable weight loss results after an initial adjustment period. However, the chronic effects of this diet have been found to not last after 12 months, so this isn't necessarily the best long term choice

Low carb – generally low carb diets tend to be more manageable than keto as they're not quite as extreme. Some people find cutting out carbs such as confectionery and white bread, but keeping healthier carb options such as wholegrains, fruits and pulses, to be a good approach for them.

Any downsides?

Keto – more or less cutting out an entire food group is challenging, and instinctively can feel a little unnecessary. Carbohydrate foods can bring lots of healthy nutrients to our diet – for example fibre is only naturally present in carbohydrate-rich foods – so removing carbs means removing fibre.

When limiting carbs, most people will experience at least some short term side effects such as dizziness and lack of concentration. It is also not the most social approach as finding suitable meals at restaurants can be a challenge. Longer term, there are questions about how sustainable it is, and there are not enough long term studies yet to validate the safety of this type of diet.

Low carb – depending on how low carb intake is dropped to, some people can experience feelings of irritability and fatigue when initially making the reduction of carbs in their diet. This is because carbohydrates are our body's preferred fuel source, so our muscles and brain feel the impact.

What does Nutracheck track?

The app offers a Lower Carb nutrition goal to follow, where we preselect your macronutrient allowances for you. The Lower Carb goal sets your total carb intake between 30-45% of total calories, depending on how high we can set your protein intake to and keep with health guidelines. This allows you to moderately reduce your carb intake, without taking it extremely low.

Alternatively, if you'd prefer to follow an even lower carbohydrate intake through personal choice, you can use the Set My Own goal to set any target. There are no restrictions with this setting, but we do highlight our recommended ranges. This function requires you to acknowledge a disclaimer stating that you take responsibility of the choice you are making – as it goes against the guidance we would give.

To set this option via the app, in your Diary page tap on the white chart icon in the top right, scroll down and tap 'Set My Own'.

Nutritionist’s expert opinion

Keto – this diet is extremely restrictive and requires removing almost an entire food group from your diet. For me, this instinctively doesn't make sense given that carbs can be extremely nutritious and are our body's preferred fuel source. Cutting carbs out changes our natural metabolic processes, which causes me some concern. While this dietary approach may produce faster initial results, this benefit does not continue long term. If your goal is to lose weight and to keep it off, it may be an unnecessary challenge to take on a keto approach, when a more flexible approach could work just as well – and potentially better long term. There is a lack of long term evidence to support the safety of a keto diet ongoing and indeed many people tend to follow this approach on a temporary basis – so sustainability is questionable. The effects of repeatedly removing carbs and then reintroducing them can take a toll on our health if not managed correctly too, so this is another consideration when thinking about the long term impact.

Low carb – this approach may work for some people as they can selectively remove less nutritious carb choices – while still including an intake of healthy, high fibre carbs. Some people find lowering carbs, while upping protein helps to keep them feeling fuller – as protein is very satiating – which can make it easier to stick to a reduced calorie intake for weight loss. Initial weight loss on a lower carb diet may be a little faster than some other approaches, mostly due to water loss – and some people may find this helps their motivation. It's important to stress however that long term, these effects do not continue and lower carb diets have been shown to be no more effective for weight loss than lower fat diets for example.

In summary

Keto diets are very extreme and are not backed by long term studies, so they're not something we would actively encourage.

Lower carb diets may be preferrable to some and can be managed healthily.

For further reading: The truth about carbs - NHS

Nutritionist Emma Brown (ANutr), MSc Human Nutrition is passionate about how food science applies to the human body, and how the nutrients in what we eat affect us and ultimately have an impact on our health.