The keto diet restricts fruits that contain carbohydrates, like tomatoes. Learn if tomatoes are keto and suitable for weight loss.
- Tomatoes are keto.
- One tomato contains 3.4 g net carbs.
- 6+ tomatoes can throw you out of ketosis.
Are Tomatoes Keto?
Tomatoes are juicy, ripe fruits that are eaten cooked or raw. Nature provides tomatoes in different shapes, colors, and nutritional values.
They are used in countless recipes to add a fresh and zesty flavor.
Tomatoes are often recommended in diets for weight loss. But can tomatoes, canned tomatoes, and tomato juice be suitable for low-carb diets because of the carbohydrates they contain?
To find out, we need to look closer at their nutritional values.
Carbs in Tomatoes
Tomatoes are a classic ingredient in recipes for salads. These are known to be relatively low in carbohydrates. On the other hand, however, tomatoes are fruits, which in turn are known for sugar.
To determine if they are ketogenic, we need to calculate the net carbs in tomatoes.
How Many Carbohydrates Are in Tomatoes?
100 grams of tomatoes provide the following average nutritional values (*):
- Energy: 18 calories
- Protein: 0.9 grams
- Fat: 0.2 grams
- Carbohydrates: 3.9 grams
- Dietary fiber: 1.2 grams
- Net carbs: 2.7 grams
In comparison, carbs predominate in tomatoes. They contain hardly any fats and some protein.
At first glance, tomatoes are a high-carbohydrate, low-fat food. They have a fat-to-net carbohydrate ratio of 0.075.
Although they contain little fiber, they are low-carb fruits.
Are Tomatoes Keto-Friendly?
Tomatoes are generally suitable for the keto diet.
Only six tomatoes can throw you out of ketosis, as it contains about 20 grams of net carbohydrates.
An average tomato has 3.4 grams of net carbs (*).
However, tomatoes are versatile in a low-carb pantry but come in various varieties.
On keto, you can eat 45 cherry tomatoes per day. One cherry tomato has about 0.45 grams of net carbohydrates (*).
On keto, you can eat 12 plum tomatoes per day. One plum tomato has about 1.61 grams of net carbohydrates (*).
On keto, you can eat 95 grape tomatoes per day. One grape tomato has about 0.21 grams of net carbohydrates (*).
Carbs in Canned Tomatoes
100 grams of canned tomatoes provide the following average nutritional values (*):
- Energy: 32 calories
- Protein: 1.6 grams
- Fat: 0.3 grams
- Carbohydrates: 7.3 grams
- Dietary fiber: 1.9 grams
- Net carbs: 5.2 grams
Are Canned Tomatoes Keto?
Canned tomatoes are poorly suited for the ketogenic diet. Because of the added sugar, one can can throw you out of ketosis.
The amount of added sugar can vary from manufacturer to manufacturer. You’re better off on keto with fresh tomatoes.
Carbs in Tomato Juice
100 milliliters of tomato juice (100%) provides the following average nutritional values (*):
- Energy: 21 calories
- Protein: 0.8 grams
- Fat: 0.1 grams
- Carbohydrates: 4.2 grams
- Dietary fiber: 0.8 grams
- Net carbs: 3.4 grams
Is Tomato Juice Keto?
100% tomato juice is allowed in moderation on keto.
Tomato juice is a fruit juice with amazingly few net carbs. You can easily drink two glasses of tomato juice daily and stay in ketosis.
Still, tomato juice is less suitable for the ketogenic diet than raw fruit. In juice, the protective fiber is missing.
However, because tomato has little dietary fiber, this disadvantage is less severe than other fruit juices.
Are Tomatoes Good for Weight Loss?
Tomatoes are undoubtedly low-carb.
Nevertheless, they have a significant disadvantage when it comes to losing weight. They contain exceptionally high concentrations of lectins.
Plants also defend themselves against predators. They produce large, sticky proteins to ward off pests and microorganisms (Dolan et al. 20104).
Lectins are plant toxins. Although we do not digest these antinutrients, they can sneak into the bloodstream through the gut.
These lectins hide in seeds, grains, leaves, barks, and hulls. It was once common to put tomato bushes in front of the pantry. The many lectins in their skins can keep insects away and sometimes even paralyze them.
Lectins bind viruses and bacteria and help them to cross the intestinal wall and reach organs (Dalla Pellegrina et al. 20095).
In addition, lectins can bind to insulin and leptin receptors, ultimately leading to weight gain (Shechter 19836).
Yes, tomatoes are low in carbohydrates and suitable for keto. However, they are not recommended for weight loss. Because of lectins, they are also pro-inflammatory and not generally healthy (Freed 19997).
Tomatoes Are Keto, but Bad for Weight Loss
The bottom line is that tomatoes are of limited use for weight loss.
If you have intestinal problems or inflammation in general, you should avoid them at all costs. If you still want to use these low-carb fruits for weight loss, there is a trick:
Remove the skin and seeds from the tomatoes.
Classic Italian tomato sauce is still prepared this way today. Pureeing the whole fruit, including seeds, only became fashionable with the industrialization of food. It is faster and saves production costs.
Carbs in Tomatoes: Keto FAQ
Are tomatoes carb free?
Tomatoes are low in carbs but not carb-free.
Are tomatoes OK on keto?
Tomatoes are allowed on the keto diet.
How many tomatoes can I eat on keto?
You can eat up to 5 tomatoes per day on keto.
Mag. Stephan Lederer, MSc. is an author and blogger from Austria who writes in-depth content about health and nutrition. His book series on Interval Fasting landed #1 on the bestseller list in the German Amazon marketplace in 15 categories.
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