Sugar and Keto Diets: how much is ok...

One of the most common questions I get from my patients on low carb or ketogenic diets is about fruit, and also which sweeteners to use when the taste buds are calling for something sweet. Let's start with sugar. Sugar comes in a number of forms. Most people are familiar with cane sugar - the white crystalline substance added to sweeten food. But sugar is also the basis of all carbohydrate foods, including starchy vegetables, grains, cereals, breads, pasta and also fruit. The sugar molecule, more specifically called glucose, is the building block of these foods, and during digestion the sugar is released and raises our blood sugar levels. 

Most people know that consuming high-carbohydrate foods every day, increases your risk of type 2 diabetes, which is a condition of chronically high blood sugar levels. Those struggling to maintain a healthy weight are also showing signs that sugar is not being metabolised well in their body, even if they don't have diabetes. 

What about 'Natural' Sugars
Other 'natural' sugars include maple syrup, coconut nectar sugar, agave syrup and rapdura, just to name a few. These also contribute to our blood sugar levels in the same way that cane sugar does - i.e. they increase it. Honey is also pure fructose, a type of sugar that is easily converted to fat in the body. Fructose in excess can result in fatty liver and insulin resistance, which increases the long-term negative effects of carbohydrates you eat later.

Craving Something Sweet
For those on a ketogenic or a low carbohydrate diet, keeping sugars and carbs down is important. Sugar cravings often subside as carbs are reduced, and this is especially so on a ketogenic diet, when the natural increase in ketones help to reduce appetite. Yet, our taste buds are often used to something sweet. For long term dietary change to become a lifestyle rather than another failed diet, it is essential that you enjoy what you eat and find it satisfying.

Following are some suggestions on how to sweeten your day, week or month (depends on how often you look for a sweet treat). But keep in mind - all sweeteners maintain cravings for sweet foods. Also, when added to high calorie foods, like a cake or muffin, they increase the feeling of reward when eating it - i.e. you want more. So by adding sweeteners to your foods you significantly increase the risk that you’ll end up eating more than you need. This can slow down weight loss, or even cause weight gain.


  • Stevia is a herb - Stevia rebaudiana bertoni - which is native to South America. Steviol glycosides extracted from the plant are responsible for its sweet taste. Stevia doesn’t contain carbs or calories and does not raise blood sugar. It appears to be safe and nontoxic. It does have an aftertaste that some people don't like, so use this sparingly. It is found as liquid drops, pure powdered stevia, or granulated with erythritol.
  • Erythritol is a sugar alcohol which is only partially digested and absorbed by the body. Erythritol occurs naturally in plants like grapes, melons, and mushrooms in small amounts. However, as a commercial sweetener, it is usually made from fermented corn or cornstarch. It provides almost zero calories and is basically carb free. Some people do find bloating, gas and loose stools after consuming erythritol, especially with large amounts. It can be found as a granulated product and also blended with stevia.
  • Xylitol is also a sugar alcohol. It is usually produced from birch trees. It is not considered 'carb free' though, as just over half is absorbed and so contributes to your carbohydrate intake. It can also cause digestive upsets like bloating and gas, depending on how much is used and the sensitivity of the individual. It is toxic and potentially lethal for pets. If you use xylitol, make sure to keep it away from your cats, dogs and other animals.

Open to Change
If you enjoy real foods in their unsweetened state, there is no need to use any of the above. But for those with a 'sweet tooth' consider that, although it might take a while for your tastebuds to adapt, over time you may discover a whole new appreciation for the subtle sweetness of natural, unprocessed foods. The most important thing though, is to enjoy the journey along the way, and who knows what kind of foods will satisfy you into the future - be open to being surprised!