Keto diets have become very popular for weight loss in recent years. However, there are potential health consequences that you should be aware of before giving into this fad.November 17, 2022 5:17 pm April 21, 2022 6:04 pm
What is the keto diet?
The keto diet is touted as a quick and effective solution to weight-loss. However, it was originally used in a medical context for paediatric patients. In fact, the keto diet was and still is utilised to help decrease the recurrence of epileptic seizures in children. As for its effects on weight loss, numerous studies have shown short-term results. Nonetheless there is still a lot of uncertainty regarding its effectiveness and safety in the longer term.
It’s easy to get lost in the world of weight-loss fad diets, each one promising quick fixes and overnight solutions. From the Atkins diet to the Paleo diet, these low-carb, high-fat and high-protein diets are often called “keto” diets. However, a ketogenic diet in the medical sense is not just any low-carb diet. Indeed, whilst most low-carb diets focus on high protein intakes, a true keto diet is centred around fat, which can provide up to 90% of daily energy intake.
In essence, the keto diet makes your body use a fuel that is different to its default choice. In fact, instead of using carbohydrates (glucose) for energy which come from fruits, vegetables, grains and legumes, the keto diet uses ketone bodies. Our liver produces these ketone bodies using the fat we have stored in our body.
One may think that burning our fat stores is a great way to lose weight. However, the liver requires very specific conditions to produce ketone bodies. Firstly, it requires an extremely low carbohydrate consumption, less than 20 to 50 grams per day. For reference, a medium apple can contain up to 25 grams of carbohydrates. Furthermore, your body takes a couple of days to reach a stage of ketosis where your body begins to use fat as fuel instead of sugar. Finally, consuming too much protein can interfere with ketosis.
“The keto flu encompasses symptoms including fatigue, irritability, nausea, brain fog, constipation and difficulty sleeping.”
The keto diet has very high fat requirements, and typically fat is eaten at each meal. Some healthy unsaturated fats are allowed on the diet, such as nuts, seeds, olive oil and avocados. However, saturated fats are encouraged in large amounts. We will discuss later why this may be problematic. Furthermore, protein is included in the keto diet. However, there is no true distinction between lean proteins and protein foods that are rich in saturated fats such as bacon and pork. Again, this may be problematic from a health perspective.
As for fruit and vegetable intake, by nature these foods are typically high in carbohydrates. Therefore most fruits are restricted, but some varieties such as berries are permitted in small amounts due to their lower carbohydrate content compared to other fruits. Vegetables are also typically high in carbohydrates, therefore they are restricted to the lowest carb varieties such as leafy greens, broccoli, brussels sprouts, cauliflower, cucumber, celery, onions and garlic.(1)
Let’s discuss 10 reasons why a keto diet may not be the healthiest choice for you.
1. Potential nutrient deficiencies
There is a reason why as dietitians, we nag about the importance of including a wide variety of fruits and vegetables in your diet. Not only do they taste amazing, but they provide your body with an array of beneficial vitamins and minerals.
Moreover, when we talk about “eating the rainbow” (i.e., eating multiple colours of fruits and vegetables), this is because each colour represents a different nutrient. So, the more variety you eat, the more likely you are to meet all your nutritional requirements. However, what happens when we cut out a large proportion of such foods from our diet, as occurs with the keto diet? You may be at risk of micronutrient deficiencies. Namely, vitamin C, B vitamins, selenium, magnesium, and phosphorus are just some of the nutrients that are commonly found in fruits and vegetables.
So, if you do choose to follow a keto diet, it’s important to make sure that you are meeting all your nutrient requirements.
2. Liver issues
Keto diets are typically much higher in fat compared to “regular” eating patterns. Moreover, the liver is our body’s main organ which metabolises fat. For those with pre-existing liver conditions such as non-alcoholic fatty liver disease (NAFLD), a high-fat diet such as the keto diet may worsen clinical outcomes.
3. Kidney issues
Our kidneys help to metabolise the protein we consume through our diet. In the UK, the Reference Nutrient Intake (RNI) for protein for adults is 0.75g protein per kg body weight per day; this equates to 56g/day and 45g/day for men and women of average body weights (75 and 60kg respectively).
However, keto diets include much higher quantities of protein per person per day. Subsequently, this may overload the kidneys that need to work extra hard to metabolise the additional macronutrients.
Keto diets are typically low in fibre-rich foods. These include fruits, vegetables, grains, and legumes. In fact, given that these foods are high in carbohydrates, keto diets exclude them from the list of “permitted foods”. However, fibre is an essential element for bowel regularity, along with hydration and physical activity. Indeed, these are the three pillars for regular bowel movements in otherwise healthy people. People on keto diets may find that they need a fibre supplement to avoid constipation.
5. Brain fog and mood imbalances
The primary form of fuel for our brain is sugar which we can obtain from eating healthy carbohydrates. However, in the absence of sugar, our body turns to fat as the primary source of fuel. Research has shown that this can lead people to feel confused and irritable. In fact, this side effect is popularly referred to as “keto flu”. Whilst the term is not scientifically verified nor recognised by medicine, many people on the keto diet report negative symptoms in the initial stage of dieting. The keto flu encompasses symptoms including fatigue, irritability, nausea, brain fog, constipation and difficulty sleeping. These symptoms usually appear between two days and one week after starting a keto diet.(2)