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What is a keto diet and how can it help you lose weight?

Following a keto diet seems to be the new diet fashion at the moment, but you may be wondering what it involves and why it’s any different than any other diet.

To understand how a keto diet can help you lose weight, it is best to have an basic understanding of how your body makes energy.

Food as an energy source

Your body needs food for various things, but one of the main things is for energy. The body can convert carbohydrates/sugars, fats and even protein into energy (although protein is not the most efficient way of making energy).

How the body uses carbohydrates/sugars for energy

When you eat foods that contain carbohydrates (bread, pasta, potatoes, rice, oats, cereals & wholegrain, high carb vegetables & fruit, beans & pulses, milk, sugar etc.) they are broken down into simple sugars (glucose, fructose, galactose) in your digestive system. Glucose and other simple sugars are absorbed into your blood stream and the body will use them to produce energy. If you consume more carbs/sugars than you actually need for your daily energy expenditure, then the body will do the following:

  • Store the excess glucose in your liver

  • Convert glucose into fat

  • Store excess fat in your liver or in other areas of your body.

Using fats for energy

When we consume small amounts of carbs/sugars or there is an absence of carbs, the body will first of all use the stored glucose for energy. Once the stored glucose is depleted, the body will start using fat as its primary source of energy.

A keto diet involves eating a low-carb, high fat diet. Eating a low carb diet “forces” the body to use fats as energy instead of glucose, which if you adhere to it properly can put the body into a state called “ketosis”*. Ketosis is the process whereby your body converts fats into ketones, which it uses as fuel. By following this type of diet, the liver becomes really efficient at turning fat into energy, so not only will it use the fats you have consumed, it will also use up the stored fats.

How many grams of carbs can you eat on a keto diet?

On a keto diet your daily consumption of carbs needs to be no more than 50 grams a day, however the less carbs you eat the quicker you should lose weight. So unlike calorie-controlled diets, you are counting grams of carbohydrates rather than calories. This may sound off-putting but if you follow the advice around what you can eat and what you can’t, there will be no need to actually count the grams of carbohydrates yourself.

Following a keto-diet, however doesn’t give you carte blanche to eat your body weight in food, you will put weight on if you do this; it is still important to eat a sensible diet. However, the good news is that by eating more fats you will feel more satiated which helps to curb food cravings and you will be more likely to eat less, naturally.

Below is a list of the foods that you can eat on a keto diet:

You can download a copy of this handout below:

Keto diet
Download PDF • 250KB

What you should avoid on a keto diet


Sugar is in soft drinks, sweets, fruit juice, sports drinks.

Chocolate, cakes, pastries, sweetened yogurts, ice cream, and breakfast cereals.

Dairy milk; this contains a type of sugar called lactose.

Sugar can also hide in many processed products, read labels carefully to avoid hidden sugars.


Starches include bread, cereal, pasta, rice, potatoes, crisps, bagels, crackers, legumes, beans, pulses, oats, muesli.

Starchy foods turn into sugar when they are digested, this includes whole-grain and wholewheat products.


Most fruit contains a lot of sugar. Tart fruit, such as berries, lemons, and limes, or fruit with a high water content, such as melons, are okay in moderate or small amounts.

Alcohol and sweeteners

Some low-carb alcohols, such as dry wines, spirits without sweet mixers, and low-carb beer, are okay in moderation. Diet drinks, dark chocolate, and non-caloric sweeteners can be used occasionally, however, some people find progress towards their health goals are slowed or halted when these items are included in the diet.

Intermittent fasting on a keto diet

Some people who do the keto diet like to do intermittent fasting, to help the body use up the excess stored glucose and put the body into ketosis* quicker. If you choose to do this, there are a few ways you could do this:

24 hour fasting: Involves eating your evening meal on one day and then not eating again until the following evening.

36 hour fasting: Eat your evening meal on one day and then don't eat any food until your breakfast 36 hours later.

5:2 fasting: For 5 days follow a normal keto diet but for 2 days consume just 500 calories on each of the days.

It is important to carry on drinking as normal during any fast period.

Note: It is not recommended fasting for long periods of time as this can cause breakdown of muscle and bring on other health issues.

* You can check whether your body has gone into ketosis by testing your urine with ketone test strips.


To find out more information about following a keto diet and for tasty recipes, check out these books:

Keto Kitchen -Monya Kilian Palmer

The 30-Day Ketogenic Cleanse – Maria Emmerich



Disclaimer: This blog post is for information only, please consult your GP before embarking on any new health regime.


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