The ketogenic diet is a low-carbohydrate diet used as a form of treatment for seizures, as well as a diet to promote weight loss. The premise of the diet is to get you in a state of ketosis so that your body uses its own fat cells for energy, instead of glucose. As all-carb foods, fruits aren't a major part of the ketogenic diet, but that doesn't mean you need to cut them out completely. You should, however, be extra cautious about how much fruit you eat. If you're not sure how fruit might fit into your ketogenic diet, consult your doctor or a registered dietitian for help.
Fruit, Carbs and the Ketogenic Diet
The ketogenic diet uses a ratio of fat to carbs to determine the amount of carbs you're allowed to have on the plan. Generally, the ratio is 3 to 4 grams of fat to every 1 gram of carb. For example, if you're following a 1,200 calorie diet, you'd be limited to about 9 to 10 grams of carbs a day, with the rest of the calories coming from fat and protein. Your doctor or dietitian determines the number of calories and carbs you need on your ketogenic diet.
Although fruits are low in calories and rich in vitamins and minerals, all the calories come from carbs. The amount of carbohydrates in fruit varies, but a typical serving, which ranges from 1/2 to 1 cup, contains about 15 grams.
Low-Carb Fruit Choices
Being limited to no more than 10 grams of carbs a day on your ketogenic diet doesn't leave you much room for carb-heavy fruit. But you may be able to fit in some fruit on occasion if you choose those with fewer carbs per serving and are careful when measuring.
Lower carb fruit options include rhubarb, peaches, casaba melon, starfruit, grapefruit and watermelon. One cup, or 122 grams, of raw rhubarb has 5.5 grams of carbs; 1 cup of sliced starfruit, which is 108 grams, has 7.3 grams of carbs; and 1/2 cup of cubed casaba melon, or 85 grams, has 5.6 grams of carbs. Half a small red or pink grapefruit weighing 100 grams has 8.1 grams of carbs. Fresh watermelon is slightly higher in carbs than the casaba melon with 5.8 grams per 1/2-cup diced serving. When comparing serving sizes and carb content, peaches are most carb-dense with 7.4 grams per 1/2 cup serving of the sliced fresh fruit.
Use a gram scale to accurately measure the fruit to keep portions and carb intake within your recommended range.
Fitting in Higher Carb Fruit
You can fit higher carb fruits into your ketogenic diet, but the portion size may be considerably small. Oranges, which are one of the most popular fruits in the United States, according to the U.S. Department of Agriculture, have 21.2 grams of carbs per 1 cup serving of sliced segments. Depending on your daily carb allowance, a 1/2-cup, or 90-gram, serving of fresh sliced oranges would use up your entire day's worth of carbs. Like the orange, apples are also higher in carbs, with 20.6 grams in one small apple with the skin, which is 149 grams total -- you'd need to limit yourself to half or less of an apple to stay in your daily carb range on your ketogenic diet. If you like bananas, you may have to limit yourself to one-third of a small banana, which has 7.7 grams of carbs in a 33 gram measurement serving.
Too Much Fruit
When used as a method for controlling seizures, carb intake is quite strict on the ketogenic diet. Going off the diet, even for one meal, can decrease its effectiveness in helping to control seizures, according to the Epilepsy Foundation.
When a ketogenic diet is used for weight loss, the rules may be less strict. However, ketosis aids in hunger control, and eating too many carbs may bring you out of ketosis and increase hunger. The hunger control may be part of the reason the ketogenic diet is effective at helping people lose weight.