Rachel Gregory is a Board-Certified Nutritionist specializing in the science/application of the ketogenic diet for weight loss, performance and overall health
Conventional science tells us fruit is a nutritious, essential part of any balanced diet — but is this the case when you’re following keto?
Fruit contains natural sugars and can be healthy in moderation, but it can still be problematic when it comes to keto and fat loss.
In this article, we will discuss how fruit affects your body, the difference between certain types of fruit and why fruit may halt weight loss.
Fruit is often portrayed as “nature’s candy.” Fruit is packed with sugar, and like most regular candy, it will spike blood glucose (or blood sugar) levels when consumed.
Spiking blood sugar levels is the primary situation we want to avoid on the ketogenic diet.
Spiked blood sugar levels causes your body to release insulin. Here’s why that’s trouble:
Insulin is known as the “fat storage” hormone. Insulin tells your body to store (or hold onto) body fat. In ketosis, we want to break fat down and use it for energy. If your blood sugar levels continuously spike and drop (or stay elevated), your insulin will do the same.
When blood sugar spikes, insulin spikes in response, therefore halting fat burning potential and preventing ketone production. Not good.
Fruits are packed with sugar. Sugar, of course, is the carbohydrate you most want to avoid on a ketogenic diet.
In addition to its addictive, disease-promoting effects, sugar consumption causes an immediate spike in blood sugar. This leads to excessive cravings and can immediately halt fat burning — everything you’re trying to avoid on keto.
Research shows that sugar can trigger reward-and-craving areas in the brain — comparable to the effect of addictive drugs. Evidence even suggests sugar can be more addicting than cocaine[*].
Obviously, processed sugars and carbohydrates play the biggest role in this addiction. But could nature’s candy be triggering some addictive properties as well?
Currently, research is lacking in this area. As far as fruit and keto go, the main challenge is finding fruits with the lowest sugar and carbohydrate content.
Fruits high in sugar — such as apples, bananas, mangos, peaches, and watermelon — are best avoided on the keto diet. Dried fruits and fruit juice, with their enormously high sugar content, should be cut out as well.
Although you have to limit your fruit intake to remain in ketosis, this doesn’t mean all fruit is forbidden.
The key is watching your net carbs for the day, and not exceeding your daily allowance. To stay in ketosis, your daily carb count should be roughly 5-10% of your daily calorie intake. This typically equates to about 25-30 grams of net carbs per day (or less than 50 grams of total carbs per day).
Net carbs are calculated by subtracting fiber from the total carbs (Total Carbs – Fiber = Net Carbs).
The reason you count net carbs on keto is that dietary fiber has no impact on blood glucose levels. It’s non-digestible, meaning it won’t spike insulin or kick you out of ketosis.
Note that it’s incredibly important to test your ketone levels any time you’re introducing carbohydrate-laden foods into your diet. That way you’ll find out how the new changes affect your ketone levels.
This may come as a surprise to you, but there is one fruit you can generously on keto:
Yep, you read that right. Avocado is a fruit, not a vegetable. Actually, it’s the lowest-carb fruit there is.
With an incredible amount of nutrients (including healthy fats, vitamins, minerals, fiber, protein, antioxidants and phytonutrients) avocados are an amazing superfood.
There’s a common misconception that avocados should be avoided due to their high carb content. However, the ratio of carbs, fiber, fat, protein and other nutrients make avocados a keto superfood.
See for yourself and check out the nutrition facts below.
½ of a Medium Sized Avocado (~ 70 grams)[*]:
- 112 calories
- 10g fat
- 6g carbs
- 5g fiber
- 1g net carb
- 1.4g protein
The benefits of consuming avocados include:
- Improved heart health
- Healthy skin, eye and hair
- Lower risk for metabolic syndrome
- Aid in weight loss
- Cancer prevention
- Better digestive health
- Hormonal balance
- Protection against insulin resistance and diabetes.
So don’t be shy! Stock up on those avocados and make sure you’re getting a healthy dose of the best keto fruit out there.
Tip: Buy avocados in bulk when they’re on sale and keep them in your refrigerator to prevent them from going bad. They’ll last for weeks in the ice box.
Other Keto-Friendly Fruits
Although a bit higher in sugar, another low carb fruit you can consume on keto is berries.
Like avocados, berries are loaded with antioxidants, vitamins and minerals while still being lower in carbs and high in fiber.
Berries have been shown to reduce inflammation, improve blood sugar, reduce insulin responses and even protect against diseases[*].
Consuming berries (such as raspberries, blueberries, strawberries and blackberries) in small amounts can allow you to stay in ketosis while still getting your fruit fix.
Here are the carb and fiber counts for berries (per 1 cup serving):
- Blackberries: 14g of total carbs, 7g of sugar, 8g of fiber and 6g of net carbs
- Raspberries: 15g of total carbs, 5g of sugar, 8g of fiber and 7g of net carbs.
- Strawberries: 11g of total carbs, 7g of sugar, 3g of fiber and 8g of net carbs
- Blueberries: 21g of total carbs, 15g of sugar, 4g of fiber and 17g of net carbs
Make sure you keep track and don’t go too crazy with berries, can hinder your fat-burning goals.
Besides its ability to prevent entering ketosis, fruit can negatively impact weight loss and your ability to develop healthy habits.
#1: Fruit and Hunger/Cravings
Not only does fruit spike blood sugar, it causes a rapid decline in blood sugar levels (just like most carbohydrates).
When you eat fruit as a standalone snack, you’ll probably feel full for half an hour. After that, hunger sets in again. This is because fruit doesn’t have enough fat or protein to keep you satiated.
Although fruit does contain fiber to keep cravings a bay, it’s usually not enough to prevent the inevitable blood sugar crash. Once that blood sugar starts crashing, the hunger and cravings begin to surface again.
Rinse and repeat.
#2: Fruit and Potential For Overeating
Aside from the blood-sugar issue, fruit contains a special sugar called fructose.
Did you ever bring home a container of grapes or pineapple, ate a few pieces, and suddenly the entire container was gone?
You’re not alone.
The combination of sneaky fructose with blood sugar spikes (and following dips) is a recipe for disaster. This inadvertently prevents weight loss for many people.
#3: Fruit and Bloating
Fruit doesn’t just mess with your mind — it can mess with your stomach.
Fructose is known to cause bloating by being inefficiently absorbed by the small intestine. This leads to gas and abdominal discomfort — something quite frustrating for someone trying to lose those extra pounds.
Due to agricultural advancements, fruit is grown to larger size today than in previous decades. Therefore, our generation consumes more fructose than our grandparents did.
Which is just another reason why it can cause more harm than good for your weight loss efforts.
#4: Fruit and Nutrition
We’ve all heard the saying: “An apple a day keeps the doctor away.” But is this really the case?
Many people believe fruit is a health food and therefore it doesn’t matter how much you eat. Er, not quite.
In moderate amounts fruit can be healthy, providing you with antioxidants, vitamins and minerals. But, when you consume excessive amounts of fruit, it adds up.
Too much fruit prevents entering ketosis. The excess fructose, spikes in blood sugar and unwanted bloat will hinder your body from using ketones as fuel.
But wait, aren’t fruits high in vitamins and minerals?
Yes, fruits have quite a few health benefits, most notably their high volume of essential vitamins and minerals. And yes, it is very important to get enough of these in your diet. But no, fruit isn’t your only option.
Follow this keto-friendly food list to get your daily dose of vitamins and minerals:
- Keto-friendly non-starchy vegetables
- 100% grass-fed meats
- Nutrient dense poultry and seafood
- Properly made greens powders
These foods come highly recommended on keto (or any low carb diet, for that matter). They provide everything you need to increase your health and prevent disease — without causing unnecessary spikes in blood sugar and insulin levels.
One meta-analysis looked at fruit and vegetable consumption in relation to breast cancer risk. Findings showed vegetable consumption was associated with a reduced risk of breast cancer, but not fruit[*].
Focus on getting the majority of your vitamins and minerals from keto-friendly sources to keep your body in fat-burning mode. Satisfy any sweet cravings with lower carb options, like a handful of berries, when needed. Enjoy avocados (the best keto fruit) generously.
Here’s one last tip for you. If you’re curious on how fruit affects you, test your blood glucose (blood sugar) levels after consuming a serving. If your blood sugar goes high and/or low within the next five hours, this indicates you’re sensitive to that particular fruit and should probably avoid it.