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In most weight loss circles, low carb dieting is viewed as one of the best ways to lose fat without having to resort to starvation. Cutting down on carbs eliminates any potential competition for fuel and so your body is more inclined to burn fat. Also, cutting starchy carbs and replacing them with non-starchy vegetables means you automatically reduce your calorie intake. A double fat-loss whammy!

However, what if you don’t just reduce your carb intake, but eliminate carbs altogether? That’s the basic premise of the ketogenic diet.


The ketogenic diet restricts carb intake to between 20 and 50 grams per day. In contrast, a low carb diet allows around 100-150 grams per day.

Restricting carbs this low forces your body to almost exclusively use fat for fuel. The trouble is, your brain only really runs on glucose (derived from carbohydrate) and can’t use fats or fatty acids. So, instead, your body converts fatty acids into a substance called ketone bodies which your brain CAN use for fuel. Note these are very different from “raspberry ketones”.

This conversion process is not very economical and it takes a large amount of fat to make a relatively small number of ketones. Needless to say, this inefficiency is very good news when you are trying to lose fat fast.

In addition, all-but eliminating carbs will significantly lower your blood glucose and pretty much remove the need for your body to produce insulin. This very firmly puts your body in fat burning and not fat-storing mode.


There are a few downsides to the ketogenic diet though none of them are too great to overcome. 

Getting into ketosis takes several days and during that time as your glucose, carbohydrate and glycogen stores are depleted, it’s very common to suffer a few unpleasant side effects. Some ketogenic dieters experience: 

  • Severe carb cravings

  • Headaches 

  • Nausea

  • Constipation or diarrhea

  • Joint pain

  • Fatigue and lethargy 

  • Disrupted sleep

Your body is very used to being constantly fuelled with carbs and while it can function happily on ketones, it takes a few days for this transition to occur. The good news is that, once you have been through the metabolic shift from burning carbs to ketones, all of these side effects will disappear.

You can also speed up your transition by purposely depleting your carb stores faster with exercise as well as drinking more water and increasing your sodium intake slightly; ketogenic diets cause initial water and salt loss which may make side effects worse. It’s also important to a) eat enough fat and b) not eat too much protein. Excess protein (more than 2 grams per kilo of bodyweight) will cause gluconeogenesis which is when some protein is converted to glucose and will delay your descent into full ketosis making those side effects last longer. 


Once you are in ketosis, you should find your energy levels return and your cravings disappear. This can take anywhere between 4-7 days depending on how “carbed-up” you were in the first place.

You’ll know when you are in ketosis because those low carb side effects will disappear, but another way to confirm you are now a fat-burning machine is to use keto sticks and test your urine. These easy-to-use and cheap to buy urine analysis sticks will reveal how deeply you are in ketosis. Keto sticks are available in most pharmacies. 

If you do a lot of intense exercises mainly using the anaerobic lactic acid system, the ketogenic diet may not be for you. Exercise lasting 30-seconds to two or three minutes relies heavily on glycogen and blood glucose and your levels will be very low. As a result, you might find that weights feel heavier than usual and/or you cannot do as many sets and reps as usual. In contrast, low-intensity cardio performance should not be affected because fat is the primary fuel and you have lots of that available.

In this instance, a cyclic ketogenic diet may be a better choice. 


A cyclic ketogenic diet involves periods of 5-6 days of very low carbs and 1-2 days of high carbs. As a result, your rate of fat burning is enhanced during the ketogenic “week” but then you restock your muscle glycogen supplies over 1-2 days so that you have lots of energy for exercising hard for the first few days the next week. Your cyclic ketogenic diet plan for seven days could look like this:

  • Saturday and Sunday AM – lots of carbs, no training 

  • Sunday PM – very low carbs, no training 

  • Monday – very low carbs, high intensity, high volume training

  • Tuesday – very low carbs, high intensity, high volume training

  • Wednesday – very low carbs, high intensity, moderate/low volume training

  • Thursday – very low carbs, no training

  • Friday AM – very low carbs,   

  • Friday PM – moderate intensity, high volume training (to spike insulin sensitivity) e.g. circuit weight training

  • Friday PM – post-workout high carbs

Such a plan should allow you to gain lean muscle and lose fat – something many people believe is impossible. And expect to feel superhuman on the first 1-2 workouts of the week as your muscle glycogen stores will be immense. You are essentially carb loading once a week. However, by the end of the week and for your final carb depletion workout, don’t expect to be setting any records! 

The ketogenic diet is not for the faint-hearted. Expect a few unpleasant side-effects and also some carb cravings before you make it into ketosis. But, for those that survive the journey, the rewards are significant weight loss and noticeable fat loss in a few short weeks. And the carb ups on the cyclic ketogenic diet are a lot of fun too!

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