Lemons and limes are keto-friendly, oranges and grapefruit only in small amounts. Lemon and lime juice add plenty of flavor for very few carbs: a tablespoon of lemon juice has about 1 g. A whole medium orange, though, contains roughly 12 g of net carbs, and half a grapefruit around 11 g, which is a large share of a 20 to 50 g daily keto allowance. Citrus juices such as orange juice are too high in sugar for keto. If you take regular medicines, also note that grapefruit can interact with several of them, including some statins and blood pressure drugs.
Carbs in citrus fruit
Per 100 g (3½ oz), from USDA FoodData Central:
| Fruit | Calories | Carbs | Fiber | Net carbs | Sugars | Vitamin C |
|---|---|---|---|---|---|---|
| Lemon, flesh | 29 kcal | 9.3 g | 2.8 g | 6.5 g | 2.5 g | 53 mg |
| Lime | 30 kcal | 10.5 g | 2.8 g | 7.7 g | 1.7 g | 29 mg |
| Grapefruit, pink or red | 42 kcal | 10.7 g | 1.6 g | 9.1 g | 6.9 g | 31 mg |
| Orange | 47 kcal | 11.8 g | 2.4 g | 9.4 g | 9.4 g | 53 mg |
| Lemon juice | 22 kcal | 6.9 g | 0.3 g | 6.6 g | 2.5 g | 39 mg |
| Lime juice | 25 kcal | 8.4 g | 0.4 g | 8 g | 1.7 g | 30 mg |
Per typical portion
| Portion | Net carbs |
|---|---|
| 1 tablespoon lemon or lime juice (15 ml) | about 1 g |
| Juice of 1 lemon (about 45 ml) | about 3 g |
| ½ medium grapefruit (about 120 g) | about 11 g |
| 1 medium orange (about 130 g) | about 12 g |
| 250 ml glass of orange juice | about 25 g |
Lemons and limes on keto
Lemons and limes are among the most useful foods on keto. You rarely eat them whole, but their juice and zest add brightness to water, dressings, marinades, fish and vegetables for very few carbs. Our guide to keto salad dressings uses them often, and our article on lemon water covers the claims made about it.
Oranges and grapefruit on keto
A whole orange or half a grapefruit can fit on a more relaxed low-carb diet, but on strict keto they use up a lot of your allowance. Options:
- Use a few segments in a salad rather than eating a whole fruit.
- Add zest, which has strong flavor and almost no carbs, to dressings, yogurt or baking.
- Choose berries instead if you want fruit. Our list of low-carb fruits compares options.
- Avoid juice. Orange and grapefruit juice are concentrated sugar without the fiber of the whole fruit.
Benefits of citrus
Citrus fruits are excellent sources of vitamin C, which the NHS says helps protect cells, keeps skin, blood vessels, bones and cartilage healthy, and helps wounds heal. Adults need 40 mg a day in the UK, and an orange provides more than that. On keto, when many fruits are limited, vitamin C can run low, so lemons, limes and low-carb vegetables such as peppers and broccoli help fill the gap. Our guide to nutrient deficiencies on keto explains which other nutrients to watch.
Citrus also contains citrate, which helps prevent some kinds of kidney stones. Adding lemon juice to water is one of the tips the NHS gives for preventing kidney stones, which are more common on long-term keto. Our guide to keto and kidney stones explains more.
Grapefruit and medicines
Grapefruit and grapefruit juice can change how your body processes some medicines, so that too much or too little of the drug stays in your system. The FDA lists some statins used to lower cholesterol, such as simvastatin and atorvastatin, and some blood pressure medicines among the drugs affected. If you take any regular medicine, check the leaflet or ask your pharmacist before eating grapefruit. Seville oranges, pomelos and some other citrus fruits can have similar effects. Our guide to grapefruit benefits covers this in more detail.
Keto-friendly ways to use citrus
- Lemon or lime water, hot or cold, with mint or cucumber.
- Salad dressings: lemon juice, olive oil, mustard and herbs.
- Marinades for fish and chicken: lime, garlic and chili, or lemon, oregano and olive oil.
- Finishing vegetables: a squeeze of lemon over roasted broccoli, green beans or asparagus.
- Zest in baking: lemon zest in almond flour muffins or a keto cheesecake. Our keto cheesecake uses it.
- Citrus salads in moderation: a few grapefruit segments with avocado and rocket.
What about pomegranate?
Pomegranate, often pictured with citrus, isn’t citrus and is higher in carbs, with around 19 g per 100 g of seeds. A tablespoon of seeds sprinkled over a salad adds color for a few grams of carbs. Our guide to pomegranate benefits explains more.
A citrus-friendly keto day
| Meal | Where the citrus goes |
|---|---|
| Breakfast | Scrambled eggs with spinach, and hot water with a slice of lemon |
| Lunch | Tuna salad with avocado, cucumber and a lemon and olive oil dressing |
| Snack | A few grapefruit segments with a handful of almonds, if your carb budget allows |
| Dinner | Salmon baked with lime, garlic and chili, served with green beans |
Using lemon and lime this way adds flavor and some vitamin C for just a few grams of carbohydrate across the whole day. If you want a whole orange or half a grapefruit, plan it into your daily total and balance it with lower-carb meals elsewhere. Our guide on how to calculate net carbs explains how to fit it in.
Common questions
Does lemon juice help on keto?
It doesn’t speed up fat loss or ketosis, but it’s a useful low-carb way to flavor water, food and dressings, and it adds a little vitamin C and citrate.
Does lemon water break ketosis?
No. A squeeze of lemon in water adds only about 1 g of carbs.
Are clementines and mandarins keto?
They’re similar to oranges in carbs per 100 g, but smaller. One small clementine has roughly 8 g of net carbs, so it may fit occasionally on a less strict low-carb diet.
Is orange zest keto?
Yes. You use so little that it adds almost no carbs.
Safety note: Keto isn’t suitable for everyone. If you have diabetes, kidney or liver disease, take regular medication, or are pregnant or breastfeeding, talk to your doctor before cutting carbs this far (why it matters).
This article is general information, not medical advice. Talk to your doctor or a registered dietitian before making big changes to how you eat, especially if you have a health condition, take regular medication, or are pregnant or breastfeeding.
