What Foods Can't You Eat On The Keto Diet? (Dietician Answers)

The keto diet is a powerful tool to supercharge the way you lose weight and feel better than you ever have while STILL being able to eat all your favourite foods. However, even as fun and flexible as the keto diet can be, there are certain food items that you will have to remember to limit or avoid to ensure you are getting the benefits of the diet. Let’s start first with why it’s important to limit these types of food in the first place

What are the possible nutritional effects of a Ketogenic diet?

The foods you have to avoid all stem from what the ketogenic diet is and what it aims to do in your body. Very briefly, the traditional diet followed by most people has a mixture of carbohydrates, proteins, and fats.

The keto diet leverages your body’s response to a lack of carbohydrates in the body. When the body has little to no carbohydrates to use for energy production, it shifts to finding other means to produce energy, such as utilising fat as a source of energy.

Fat is metabolised in the body to eventually yield ketone bodies, which can be used by the body for energy production and the maintenance of vital functions in the different bodily systems. When using fat as an energy source, it can promote weight loss. This is the metabolic state of ketosis that the keto diet is typically trying to put you in for its best results.

Very little carbohydrates are allowed to ensure that the body is primarily using fat as its main energy source. The percentage range for protein is also there as the body is capable of creating glucose from certain amino acids and thus would kick you out of the ketosis you are looking for on the diet.

With all this being said, this is why we still need to be mindful of the foods we are eating on the diet as this can have a huge impact on whether the diet is effective at all for you.

The keto diet foods to eat

Generally speaking, the foods you would need to avoid are high carb foods to be able to follow this diet. This includes your starches and alcoholic drinks.

Taking in these food items even in small amounts can easily get your carb intake to more than 5-10% of your total calories per day and thus kick you out of ketosis.

Foods to avoid on keto diet

Here's a list of examples of high carb foods you can't eat on a keto diet.

Grains and Cereals

Grains contain a lot of carbohydrates as these are primarily made up of starch or a long chain of carbohydrates. On the keto diet, it does not matter whether the grain you are consuming is whole-grain or the dehulled option, both will contain what is known as the endosperm, which is the part of the grain that is highest in starch. Within this, you cannot just consume grains on a strict keto diet.

Fruits

Fruits have carbohydrates in the form of fructose. That is why a good option here is to opt for lower glycemic index fruits if you will be taking in fruits as these typically either have a lower fructose content, a high fibre content, or a mix of both. Fruits to avoid include: oranges, bananas, grapes, mangos, apples, prunes, plums and fruit juices to name a few. These fruits yield more net carbs that can easily affect your ketosis.

Honey and Syrups

Honey and maple syrup are also made up of simple sugars and are an easy way to rack up your carbohydrate intake. They are also very easy to use and add to foods and often increase not just your sugar intake but also your calorie intake.

Starchy vegetables

Starchy vegetables like potatoes, squash, sweet potatoes, corn, yam, and peas are all high in starch and should be avoided in the keto diet.

Sugary Foods and Beverages

Table sugar is made up of glucose and fructose which are both simple sugars known as monosaccharides thus we will want to avoid these.

Most beverages like canned soda, bottled fruit juices and refreshments often contain added sugar that can easily mess up with ketosis.

Gluten Free Baked Goods

Labelled baked goods can sometimes contain the words "gluten-free" but not all gluten-free flours that can be used in the keto diet. Some are made up of rice, oats, and potato which should be avoided when on keto

To know if a baked product is keto safe, always look for the keyword "keto friendly" on its label.

Milk, Dairy, Chocolate and Sugary Drinks

1 cup of whole milk contains about 11 g of carbohydrates. Adding these even in small amounts can add up and easily kick you out of ketosis. This goes the same with other dairy products like ordinary or flavoured yoghourt and some dairy based drinks.

Chips, Starchy foods and other Processed foods

Aside from most processed food being flour or potato-based or refined carbs, they tend to have added sugars and syrups as well that can easily add up to a much higher carb intake than you expect. These processed food items can also often contain trans fats that may cause inflammation.

The Keto Diet Foods to Eat

With all these foods to avoid, here are some great foods you can eat on the keto diet:

1. Poultry, fish, shellfish, eggs, lean meat and occasionally can include processed meats like bacon, sausages, etc.,
2. Nuts and seeds like chia seeds, flax seeds, pumpkin seeds, almonds, cashews, macadamia nuts.
3. Low-glycemic index fruits like fresh berries (raspberries, strawberries, blueberries), kiwis, avocados, and lemon
4. Keto-friendly baked goods typically made from almond or coconut flour
5. Sweeteners with erythritol, stevia, monk fruit, allulose, or sucralose. These sweeteners all work in such a way that they sweeten the product they are used in but are not processed by the body as carbohydrates.
6. Non Starchy Vegetables like leafy greens (spinach, lettuce, arugula, bok choy, or collard greens).
7. Healthy fats and oils like coconut oil, olive oil, avocado oil, ghee,
8. Keto-friendly processed food that use low carb substitutes for their chips and goods

Summary

These are some common food items to avoid on the keto diet as well as what you should be eating on the diet. As you can see, it can be quite tricky to avoid hidden sources of carbohydrates in your diet which is a big goal when on the keto diet.

The main thing is to always plan what you’re going to eat. That way, you’ll never be caught off guard and you’ll always be able to stick to the keto diet. It may be challenging at first but once you get the hang of everything, it will become second nature and the results you get from the diet are worth it!

* These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.

Written By Author

Joyceren Miyah Genobaña, Expert Dietician & Nutritionist

Reference List And Sources

1. Hall, K.D., Guo, J., Courville, A.B. et al. Effect of a plant-based, low-fat diet versus an animal-based, ketogenic diet on ad libitum energy intake. Nat Med 27, 344–353 (2021). https://doi.org/10.1038/s41591-020-01209-1

2. Nelson, A.B., Queathem, E.D., Puchalska, P. et al. Metabolic Messengers: ketone bodies. Nat Metab 5, 2062–2074 (2023). https://doi.org/10.1038/s42255-023-00935-3

3. Tristan Asensi M, Napoletano A, Sofi F, Dinu M. Low-Grade Inflammation and Ultra-Processed Foods Consumption: A Review. Nutrients. 2023; 15(6):1546. https://doi.org/10.3390/nu15061546