Guide to Ketosis

What is Ketosis?

Ketosis is where your body burns stored fat for energy, which will result in faster weight loss.  This page will help you understand ketosis in a lot more detail.

A non-dieter usually eats around 260g of carbs per day. When you reduce your carbs dramatically to 65g or less you should go into ketosis.

Ketosis is based on reducing your carb intake and therefore you will increase your protein and fat intake.  As it is your carb consumption that is important it is OK that your proportion of proteins and fats may be higher than normal.  Calories are less important also, for ketosis it is really only reducing the carbs that will make the biggest difference.  If you want to have rapid weight loss then you may want to try our TFR Plan.

If you have not done a low carb diet before we would suggest you start at a the higher level of carbs (65g) and then reduce the amount by 5g a day until you see some side effects but do not go below 50g of carbs. If you start low in carbs you will never know your upper limit and some people may need less carbs to get into ketosis.  It can take a few weeks to get the carb mix just right for you.

There are 2 types of side effects – in the first few days as your body gets used to less carbs and then once you are fully in ketosis and burning stored fat.

Side effects in the first few days can include:

Headaches, nausea, upset stomach, lack of mental clarity (brain fog), sleepiness, fatigue, “ketosis flu” (a flu-like feeling!), hunger, needing to go to the loo more, dizziness, constipation, sugar cravings, hair loss, metallic taste in your mouth.

Any of these signs in the morning are a sign that you had the right level of carbs the day before! The headache is probably the most common side effect and it is definitely better when you drink more water, at least 2 litres (8-10 glasses) and more if the weather is warm.

Side effects once in ketosis, day 3-5 and beyond, can include:

Decreased hunger, bad breath, funny taste in your mouth, increased thirst, increased energy, better sleep, clearer thinking, a “buzzed” feeling, decreased cravings, fast weight loss, losing inches over body, a cold to the bones feeling.

You may only get one or 2 of the “in ketosis” side effects and the bad ones tend to fade over time. The lack of hunger mostly stays though, which is a sign that ketosis is occuring.  If you can cope with the first few days and get in to ketosis it becomes much easier.

How to Tell if You Are in Ketosis

Knowing the signs/side effects of ketosis should mean it is clear when you are in ketosis. 

However if you are not sure you can buy keto sticks to test your urine.  The sticks turn pink or purple if it reads ketones. A dark colour can mean that you are dehydrated not further into in to ketosis.  If you have recently drunk a lot of liquid the result will be lighter or even a false negative.  Sometimes the keto sticks can be misleading so please try to understand the signs of ketosis and not rely on the sticks.

Once You Are in Ketosis

When fully in ketosis the calories you consume do not need to be counted. Technically you could have 2000 calories or more. You lose weight, and fat, through the process of ketosis and your calories should not count. That said many customers find low carb and low calorie works well for them. It is important that you give it time to find what is right for you.

Still need more help?

Most of our knowledge comes from personal experience and google searches.  If you are still not sure if ketosis is right for you, please email Billy or do an internet search.  You will find a lot of information and resources online, one of the best websites is HNS choices.  Please also remember to check with your doctor that this type of diet is right for you.  We are not medically trained nor dietictans at Billy’s Diet.  Only our TFR plan has been dietitian approved.

Things To Consider

You will feel unwell for the first few days while you body gets used to less carbs, it’s like a detox. A lot of people give up at this point but if you can keep going it is worth it! By day 3-5 you should be in ketosis and then you will feel better (usually). That does not mean it is easy once you are in ketosis but as most people don’t feel hungry it certainly is easier.

It can take a while to get the carb level right for you, everyone is different.  You may need to reduce your carbs over a few days or weeks in order to get in to ketosis.

Generally strenuous exercise and ketosis don’t mix, as all your energy is coming from stored fat, not calorie consumption. If you are a regular gym-goer, then our calorie-controlled VLCD plan is probably a better option for you.

Remember that while in ketosis, the amount of calories from protein and fat you consume are of less concern than the carb level. As long as your carb intake remains low enough, your body will use stored fat for energy, and you should lose weight. As such, you can expect the proportion of fats and protein in your overall intake to be significantly higher than they normally would be.

When in ketosis, the side effect of reduced hunger may mean that you are tempted to skip meals or packs – this is not wise and can lead to unwelcome effects. Your body still needs to take on a certain amount of energy throughout the day. Do not skip meals – you should aim for at least 600kcal over the day.

The most important thing with ketosis is knowing what you are getting into. It cannot be done without a certain amount of organisation. I have put together is list of do’s and don’t’s to help you decide if it is right for you!

The Do’s and Don’t’s!

Yes, this is a long list but it will help you decide if ketosis is right for you.

  • Do – Speak to your doctor before buying any diet plan. In particular a low carb diet might not suit you medically and it could affect your health. It is always best to be sure, especially if you have any pre-existing medial concerns.
  • Do – Give it time to work, it can take several days or even weeks to get the amount of carbs right for you.
  • Do – Eat at least 600 calories per day. While the upper calorie limit is not so important the lower one is. You must have at least 600 calories or your body will go into starvation mode and hold on to all the nutrients it receives. This will stall your weight loss.
  • Do – Be very careful what additional food you eat. With both of our ketosis plans there is a strict list of foods you can eat from. Eat the wrong thing and you will fall out of ketosis.
  • Do – Measure as well as weigh yourself. Some weeks you may lose inches, not pounds. This is especially true if you do any exercise – muscle mass weighs more than fat and takes up less space!
  • Do – Get the right foods in. Generally low calorie versions of things like mayo are actually higher in carbs than the full fat ones. Check all labels carefully. Protein is good – ham, tuna, cooked chicken – all low in carbs and ideal for keeping to hand.
  • Do – Be prepared to write everything down! Check the ingredients of everything and write down even a mouthful of food. There are websites and apps that can keep track for you.
  • Do – Drink at least 2 litres of water. Not only does it flush your system helping weight loss, it is also part of the chemical reaction of ketosis, without water it will not work.
  • Do – Understand that certain foods might cause your weight loss to stall but you stay in ketosis.
  • Do – Make a decision regarding citric acid (CA). CA is found in most fruit juices, fruit squash and fizzy drinks. It can knock some people out of ketosis.
  • Don’t – Struggle by yourself! We are here to help and support you. You can email us, send us a message through our Facebook page or join our closed Facebook Group. We try to respond quickly and are always happy to hear from you.


  • Don’t – Skip meals! We’ve mentioned it above, but it’s here again because it’s important – you need that 600kcal over the day.
  • Don’t – Eat carbs! Avoid bread, rice, pasta, potatoes to name a few. You need to watch every mouthful, even a small amount of the wrong food can knock you out of ketosis.
  • Don’t – Expect results overnight! Although you can expect fast weight loss if you have it right, it will still take time for you to reach your goals. Some weeks your weight loss will be less and others you will lose inches and rather pounds. You may hit a stall and not lose weight for a few weeks.  Don’t give up and look at the bigger picture.
  • Don’t – Expect week 1 loss to be repeated in week 2. Most people have a big first week loss and a much smaller second week. This is normal as your body gets used to losing weight. Generally our customers have found that weighing monthly is best.
  • Don’t – Start a ketosis unless you intend to stick to it for a long period, at least 1 full week, preferably longer. Around a month seems to be the ideal time to see a noticeable difference.
  • Don’t – Buy a ketosis plan without realising what you are getting. If you are not 100% sure it is suitable for you then we also have a low calorie plan which might be better for you.
  • Don’t – Buy a ketosis plan if you want to take the weekends off.
  • Don’t – Buy a ketosis plan if you want to drink alcohol.  Drinking while in ketosis is dangerous.