Fruit and the Keto Diet: Is it OK to Eat Fruit?
Is fruit and the keto diet compatible? Lots of people see fruit as healthy – they’re full of nutrients, they’re low in fat (which non-keto followers mistakenly believe is a good thing) and they’re high in fiber. For these reasons, many are tempted to give fruit a pass. But is this correct? Is it OK to eat fruit on the keto diet?
The thing is, fruit is a carbohydrate and it can knock you out of ketosis quite easily. Ketones – the fuel source that underlies the keto diet – is made in the liver. So, anything that impacts the liver is going to have a dramatic effect on our ketone production. Fructose – one of the main sugars found in fruit – is mainly metabolised in the liver. We’ll come back to this shortly, but let’s get some basic concepts right at the beginning.
Fruit and the keto diet: the problem with fructose
Broadly speaking we consume two different types of carbohydrates: glucose (typically from starchy foods) and fructose (from fruit). Glucose is used by practically every cell in your body, whether you’re in ketosis or not. Fructose however can only be metabolised in the liver. Fructose cannot be used by every cell in the body. What does this mean? Since fructose cannot be used by your entire body, it’s typically stored as fat in the body. (Glucose on the other hand is a near-universal energy source and can be burned up readily). So, fruit can make you fat. But that’s not the only problem with fruit.
When you eat glucose, it takes a smaller toll on your liver as all cells in your body can metabolise glucose. However, when you consume fructose, your liver is doing all the work to process it and this process ends up with the liver storing a lot of glycogen (a substance deposited in bodily tissues as a store of carbohydrates).
Fructose sabotages ketosis
Glycogen is stored differently in the body: in muscle tissue and in the liver. Liver glycogen stores are used to maintain normal levels of glucose in the blood. Muscle glucose is used for energy, to fuel activity.
Ketosis can only happen when your liver glycogen is used up. If you’re always refilling your liver glycogen by eating fruit, you will never get into ketosis. In some ways, eating fruit is more counterproductive to getting into ketosis than eating regular carbs since ketosis needs liver glycogen to be exhausted (not so much muscle glycogen). Eating fruit stops ketosis production more than regular carbs.
So, when it comes to the fruit and the keto diet are there any fruits you can eat? The good news is that, yes, there are some fruits that are keto-compatible so long as you only eat them in moderation. Let’s count them down.
What fruits can you have on the keto diet?
Fruit and the keto diet #1: Avocados
Yes, yes, avocado is a fat but it’s still a fruit and it does contain fructose. It’s recommended you only eat one avocado a day.
Avocados actually have two times the potassium than a banana. Potassium – and other electrolytes such as sodium and magnesium – are very important when you’re on the keto diet as you can lose electrolytes quite quickly when you’re starting keto. So, it’s important to keep these levels topped up (especially if you want to avoid the keto flu)
Avocados are loaded with vitamins A, C, K, E and B5. Vitamin B5 is important for correct adrenal function – important if you’re suffering from low energy levels.
Avocados are also loaded with anti-inflammatory fats. (All disease is linked to inflammation, so this is a great benefit).
Fruit and the keto diet #2: Berries
Blueberries, blackberries, raspberries, strawberries, cranberries – they’re all acceptable on the keto diet. Berries have a low glycemic load (how much the food will raise a person’s blood glucose level after eating it) and are relatively low in fructose. They are also high in antioxidants and polyphenols (plant compounds that have numerous health benefits including boosting digestion and brain health, as well as protect against heart disease, type 2 diabetes, and even certain cancers.)
Blackberries are low in carbs – about 3g of net carbs per 100g of blackberries. Even if you count total carbs, fiber etc. it’s about 15g. You can have about 1/4 cup or 32g of blackberries a day without any problem.
Raspberries are similar to blackberries when it comes to the keto diet. You can have a quarter cup without worrying about coming out of ketosis. (There may be a temporary slow down of your ketone production but your body will quickly overcome this.) Raspberries have the added benefit of decreasing the appetite and increasing satiety. They are great for satisfying sugar cravings.
Strawberries – you can have slightly more strawberries as they have a higher water content. Maybe 1/2 cup but less if you can.
Fruit and the keto diet #3: Pomegranate
The sugar content of pomegranates is moderate. It’s not the lowest but it’s not too high either, approximately 12g of sugar per 65g of pomegranate seeds.
Pomegranate is great if you’re prediabetic or have Type2 diabetes as it helps increase the size of beta cells in the pancreas and help stimulate healthy insulin levels.
Pomegranate also helps boost brain and heart health and reduce the risk of certain cancers as it’s loaded with antioxidants.
Fruit and the keto diet #4: Grapefruit
Grapefruit has been shown to regulate cholesterol.
Grapefruits also contain a special antioxidant that helps improve insulin sensitivity and helps helps the liver burn fat instead of storing it.
A study showed that grapefruit can lower blood sugar levels as well as drugs such as metformin which is often prescribed to diabetics. Why take an artificial drug when nature does just as good a job?
Fruit and the keto diet #5: Coconut
Coconut is a fatty fruit. 60% of coconut is MCT (medium chain triglyceride) – a natural oil with tonnes of health benefits. MCT is a great source of energy as it bypasses your liver and quickly enters the bloodstream and your cells’ mitochondria (as all good students know is “the powerhouse of the cell”!)
Coconut contains lauric acid which has antiviral and antimicrobial properties.
Coconut can also improve levels of good cholesterol, HDL and large particle LDL (which is the good part of the otherwise bad cholesterol, LDL).
What fruits should you avoid on the keto diet?
We’ve looked at which fruits are OK on the keto diet. Now, which ones should we avoid? Here they are:
- Dried fruit
Why are these incompatible with a keto diet? They are too high in fructose levels. Remember, fructose can only be metabolised by the liver and by consuming these fruits and their high fructose concentrations, you are putting a strain on the liver which can lead to conditions such as fatty liver disease (which would be more accurately described as sugary liver disease).
Eat the fruit, don’t drink the juice!
Finally, it’s important you eat the fruit and not drink a fruit smoothie or a juice. These are basically sugar water. Yes, they have vitamins and nutrients but their sugar content is crazy high and you’re not benefiting from the fiber. So, give the drinks a miss and stick with only eating the whole fruit.
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