BSc Sports and Exercise Science 

Personal Trainer and

Nutrition Coach 

* Results may vary from person to person 

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The Ketogenic Diet- What is it and what are the Pros and Cons?

July 16, 2017


There is a lot of controversy over this very low carb, high fat diet. If you are interested in finding out the facts about the hot topic diet, I’m hoping this will clear a few things up. The information in this blog is based on scientific studies and at the end I have added my personal opinion on the diet. This blog is more on the geeky side (being a sports scientist I do love my scientific facts haha) I promise not all my blogs are this nerdy, and if you have trouble understanding any of the more technical parts just shoot me a message and I would be happy to explain and give you more info :) 




The Ketogenic (Keto) diet is a high fat low carbohydrate diet with medium-high protein intake. However it is not your usual low carb diet where you skip adding rice noodles to your meal and replace it with some zucchini noodles- this is an extremely low carb diet where you have to be so limiting on carbs that that your max daily intake is a few pieces of broccoli and a handful of green leafy veg, for those of you tracking macros you should not exceed 40-50g of carbohydrate a day (all coming from veg). So for this diet you can forget a treat of some nice fresh fruit or a dried date! 


The drastic reduction on carbs puts your body into a metabolic state called Ketosis. Your body switches to burning fat for fuel instead of glucose (from carbohydrates) due to the lack of carbs consumed. 


A normal/ low carb diet where you eat low carb meals for 2 meals a day and refuel after a workout with a high carb meal, your body would use fat for fuel during low intensity daily tasks such as walking and completing day to day activities. Your body would then switch to using glucose (from carbs) as fuel when completing high intensity work such as sprinting or weight lifting. However, when your body is in a state of Ketosis you will use fat for fuel throughout your high and low intensity work. 


What are the benefits of this severely restricting diet? Well... there are many benefits to this diet, to touch on a few top ones: 


  • When you eat carbs they are turned into glucose in the blood this then creates a spike in insulin, a hormone released by the body that transports the carbs (now in the form of glucose) to the cells (e.g muscle cells) for use or storage. On the Keto diet your body will not receive carbs, only fats therefore insulin levels will remain low, instead ketones are created from the fat you consume for fuel. This is a major contributor to fat loss through your body burning fat for fuel instead of glucose. 

  • The Keto diet has been shown to be much more effective at body fat loss than a low fat diet. 

  • Studies have shown that by eating fewer carbs and higher fats and protein you will most probably experience a reduction in appetite. Now isn't that what we all want on a diet? NOT BEING HUNGRY!! 

  • An Increase in good cholesterol (HDL) and a decrease in triglycerides- high levels of blood triglycerides are a major factor contributing to heart disease. 

  • The Keto diet has proven very effective for people with diabetes, epilepsy, cancer and Alzheimer's disease. 


So how do you get your body to work in a Ketogenic state? Well it's not as simple as just cutting out the carbs for a few days... On a ketogenic diet, your body undergoes many biological adaptions, including a reduction in insulin and increased fat breakdown, to get to the stage of Ketosis can take up to 3 weeks. This diet takes commitment I tell ya! 



So before you all jump on the bandwagon and start the Keto diet I want to touch on one downside of the Keto diet (besides having awful breath). If you do stay on the Keto diet for long periods of time (by this I mean going 5-6 months with NO high carb meals or days) your body may lose the ability to use carbohydrates which may cause a large spike in bloody glucose when you eat carbs due to lack of insulin being released. Basically what I'm saying is your body forgets how to use cabs so really struggles to use them for fuel when you do eat them again. Therefore I would suggest a few high carb days every couple of months so that you remind your body how to use carbs for fuel (this may not be applicable if your on the Keto diet for medical reasons). 


There are a few short term or smaller side effects, such as lethargy, bad breath, dehydrated, insomnia, digestive issues and short term decreases in performance. However these are not usually long term and can be managed. 


Because carbohydrates are restricted to less than 50 grams a day, you can get deficient in micronutrients such as: Thiamin, folate, calcium, iron, potassium, and magnesium are typically inadequate in low-carb diets. To avoid this I would suggest a high-quality multivitamin. 


Overall I believe the Keto diet has many benefits, as with any diet it depends what your goals are. If you are looking to lift heavy weights and build muscle, this may not be the diet for you as you will need the glucose from carbs to refuel your muscles to help them recover and build muscle tissue. However if your looking to burn fat and loose weight through diet with small amounts of lower intensity exercise, then this may be a good diet option for you to try!  But, as with any diet, it will only be effective if you are consistent and stick to it long term. 


I have personally never tried the Keto diet, I do stick to a relatively low carb diet with high carb meals surrounding my workouts, my goals are to build muscle and therefore my body works well with a high carb post workout meal. This is the reason that I have never tried the Keto diet. But this is not to say I don't understand the benefits this diet has, so depending on your goals it may be a diet to try?    



I have built an example of a day on the Keto diet, there are many more low carb, high fat foods I have not listed here, but take a look at the options. 

Breakfast: Eggs, bacon and mushrooms or Greek yoghurt with nuts, seeds and coconut. 


Lunch: Bun-less Burger with avocado, lettuce, cheese and tomato. Or ham and cheese omelet with avocado and vegetables.


Dinner: White fish or chicken with pesto cooked in butter with asparagus. 


Snacks can be: Nuts, cheese, olives, avocado or yoghurt. 


Hope you have found this interesting, any questions drop me a message :) 


Kasia xx 


BSc Sports and Exercise Science,

Personal Trainer and Nutrition Coach

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