The ketogenic diet is a high-fat diet that drastically restricts your intake of carbs to around 50 grams per day.
To achieve this, the diet requires you to cut out or severely limit your intake of carb-rich foods, including grains, legumes, starchy vegetables, and fruit.
Though tomatoes are commonly considered a vegetable, they’re botanically a fruit, causing some to wonder whether they can be included in the ketogenic diet.
This article discusses how keto-friendly tomatoes truly are.
How to achieve ketosis on a ketogenic diet
The ketogenic diet is designed to put your body in ketosis, a metabolic state in which your body starts burning fat for energy and producing ketones as a byproduct.
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To achieve ketosis, your body needs to switch from using carbs to using fat as its main fuel source. To make this possible, your daily carb intake needs to drop to less than 5–10% of your daily calories, typically adding up to less than 50 grams of carbs per day.
Depending on the type of ketogenic diet you follow, the reduction in calories is partially offset by an increased intake of calories from fat or fat together with protein.
Fruit, such as apples and pears, contain around 20–25 grams of carbs per serving. This groups them with other carb-rich foods, such as grains, legumes, starchy vegetables, and sugary foods — all of which are restricted on a ketogenic diet.
Summary: A ketogenic diet is designed to allow you to reach ketosis. For this to happen, you must severely restrict your intake of carb-rich foods, including fruit.
Tomatoes are different from other fruit
Botanically speaking, tomatoes are considered a fruit. However, unlike other fruit, they’re considered keto-friendly.
That’s because tomatoes contain around 2–3 grams of net carbs per 3.5 ounces (100 grams) — or up to 10 times fewer net carbs than most fruit — regardless of their variety.
Net carbs are calculated by taking the carb content of food and deducting its fiber content.
Hence, tomatoes are much easier to fit within the daily carb limit than other fruit, which is what makes tomatoes keto-friendly. The same can be said of other low-carb fruits, including zucchini, peppers, eggplant, cucumbers, and avocado.
In addition to their low carb content, tomatoes are rich in fiber and contain a variety of beneficial plant compounds, which may be lacking on a strict ketogenic diet. There are two more reasons to include them in your keto diet.
Summary: Although technically considered a fruit, tomatoes contain much fewer carbs than other fruits. Therefore, they’re considered keto-friendly, while most other fruits are not.
Not all tomato-based foods are keto-friendly
Although raw tomatoes are considered keto-friendly, not all tomato products are.
For instance, many store-bought tomato products, such as tomato paste, tomato sauce, salsa, tomato juice, and even canned tomatoes, contain added sugars.
This significantly raises their total carb content, making them more difficult to fit into a ketogenic diet.
Therefore, be sure to check the ingredient label when purchasing a tomato-based product and avoid those containing extra sugar.
Sundried tomatoes are another tomato-based food that may be considered less keto-friendly than raw tomatoes.
Due to their low water content, they end up containing around 23.5 grams of net carbs per cup (54 grams), which is significantly more than the same serving of raw tomatoes.
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For this reason, you likely need to limit how many sundried tomatoes you eat while following a ketogenic diet.
Summary: Tomato-based products, such as sauces, juices, and canned tomatoes, may contain added sugars, making them less suitable for a ketogenic diet. Sundried tomatoes may also be considered less keto-friendly than their raw counterparts.
A ketogenic diet requires you to severely restrict your intake of all carb-rich foods, including fruit.
Though botanically a fruit, raw tomatoes are considered keto-friendly, as they contain significantly fewer carbs than the same quantity of fruit.
The same cannot be said of sundried tomatoes, as well as many other prepackaged tomato-based products, which are often sweetened with sugar.
When in doubt, always check the food label to determine whether a certain food fits in with your keto diet.