Keto diets - weight loss miracle, or just another fad diet?

Updated: Jan 25, 2020

I am certain that you have already heard of the Keto diet. It has received a lot of attention in the past couple of years as a weight loss solution. In this post, I will explore the existing evidence regarding the Keto diet.


A picture of what the keto diet DOES NOT look like

WTF is a Keto diet?

Keto is short for ketogenic, and the term ketogenic is defined as the production of ketones. The basis of the ketogenic diet is that you deprive your body of glucose derived from carbohydrates or carbs; which are a primary source of energy for the cells in your body.


This restriction causes energy stored in your muscles and liver to become depleted. As a results, your liver has no choice but to start producing ketones from fat stores as an alternative source of energy.

The idea behind the keto diet is to increase the use of fat being used for energy. In order to do this, the body needs to deplete glycogen stores through a low carb (or ketogenic) diet.


The internet has a variety of different keto diets on offer. However, the literature on ketogenic diets states that restricting carbohydrates to a no more than 50g a day or 10% of total energy intake will achieve a state of ketosis (production of ketones). To put this into context, the UK guidelines recommend adults to consume approximately 50% of total dietary energy intake from carbs or 260g.


So, what does approximately 50g carbohydrates look like?

- A bowl of porridge

- Two slices of thick bread

- A bagel

- A large banana

- A large bowl of granola – the list goes on.


High carb fruits and vegetables are normally not included in the diet, such as: bananas, dried fruit, grapes, oranges, pineapple, potatoes and parsnips. Along with grains, beans and legumes due to their high carbohydrate content.


So, what can you eat?

As I said previously, there are many variations of the keto diet. Generally keto dieters will have a high fat intake (65-75% total energy intake) and moderate protein intake (15-20%). A keto dieter will typically fill up on meat, fish, eggs, cheese, yoghurts, milk, oils, nuts, seeds, avocados and low-carb vegetables. This excludes meat/fish covered in batter or breadcrumbs – as these contain carbs. Yoghurts and other dairy products with added sugar are also off the tables. Oh yeah and those tasty honey roasted nuts – and any other kind of flavoured nuts.


You can eat some fruit on the diet as long as its within your total daily carb intake. Lower carb options such as berries can be eaten sparingly. Along with vegetables such as lettuce, kale, mushrooms, cabbage and green peppers.


Does it work?

The keto diet is originally used to treat epilepsy in children as well as other neurological diseases such as MS, Parkinson’s and Alzheimer’s disease. It may also improve blood sugar control in type 2 diabetes, potentially it can increase your good cholesterol (though the findings are inconclusive) and improve blood pressure.


However, for rapid weight loss the research is inconclusive. Sure, you will probably lose weight on a keto diet, as cutting out basically a whole food group will give you less choice and you will likely eat less as a result of this. In summary, restricting food will likely lead to initial weight loss.


Studies comparing a low-carb diet to a low-fat diet have found that those following a low-carb diet lost weight faster, however weight loss tends to plateau at around the one year mark – potentially because going that long without pizza is REALLY hard to maintain.


Another reason for quick weight loss following the keto diet is likely due to water loss. So, our bodies store of glucose in the body (glycogen) found in your liver and muscles is bound with water. Once these glucose stores are depleted, the water bound is also lost. Meaning that this loss is not fat loss, and will be regained once our bodies stores of glucose and replenished.


Lastly, some researchers have found that keto diets can have a beneficial impact on our appetite hormones. Potentially due to fat being higher in calorie gram for gram; therefore taking longer to burn. Making it more filling. Or due the satiating (satisfying) effect of dietary fat. But little evidence exists to confirm this.


What are the adverse effects?

Some dieters refer to the beginning phase of the keto diet as the keto flu – as they can feel nauseous, fatigued, hungry, tired and may experience headaches.


When carbs are consumed the body will respond with a hormone called insulin – insulin will allow nutrients into the body’s cells. One of these nutrients being protein. Therefore, when you restrict carbs, you limit the amount of protein that can get into the muscles for growth and repair.


Cutting out a food group can lead to nutrient deficiencies – the keto diet may lead to lower intakes of sodium, potassium and calcium. Plus, due to the nature of the keto diet, you may find your blood levels of cholesterol may increase – which can be detrimental to individuals with particular heart conditions.


Carb sources such as wholegrains, fruits and vegetables are rich in fibre. Now it doesn’t take a dietitian to know that fibre plays a key role in bowel movements. When you restrict carbohydrates, you restrict fibre. Therefore, the keto diet can lead to constipation. Fibre also has an important role in gut health and maintaining a balance of good bacteria that have a whole range of health benefits in immune function, inflammation and mental health.


With any diet, there is the risk of disordered eating. Restricting a food group may lead to binge later on down the line; which can lead to feelings of disappointment, guilt or shame.


The keto diet may not be well received in your social group too– as it is much harder to celebrate with friends if you cannot drink a cold pint or two or go out to that new Indian buffet for dinner.


To summarise

It is likely that by cutting out a food group you will lose weight in the short-term but this may be putting you at risk of deficiencies and related side effects in the long-term. Lowering your carbohydrate intake by reducing the amount of added sugar and refined carbohydrates in your diet is going to be of some benefit to you. Make the most of your carbohydrate intake by ensuring you eat a range of fruits, vegetables and wholegrain foods.

It is important to note that there is not a “one-size-fits-all” when it comes to the way you eat. Keto is still considered a diet, which is likely to set you up for disappointment as over 90% of diets fail. Choosing a way of eating that you can stick to, whilst encompassing general healthy eating advice, is most important when it comes to achieving healthy weight loss. Moreover, physical activity, sleep and stress levels can all impact your food choices and inevitably weight changes. So considering your lifestyle habits as a whole is a smarter move.


If you have any questions or require the reference list for this post then feel free to contact me on my email.

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