Are Potatoes Keto? How to Eat Potatoes on the Keto Diet

Potatoes are a root vegetable or tuber. On the plant, it is the underground energy storage organ. Potatoes can be found in the wild and domesticated for cultivation around 7,000 - 10,000 years ago. There is a vast biodiversity of potatoes with 5,000 known species.

The general serving size for a potato is a medium potato weighing 213 grams. The water content is approximately 82% (174 grams) and total calories for this serving size is 147 kcal.

One medium potato (213g) is made up of 90% of the calories from carbohydrates and contains 28 grams net carbs. Total carbohydrates is 34 grams with 5 grams of fiber, 2.45 grams of total sugar and 0.72 grams as fructose.

Potatoes are not considered keto friendly. But is also very low in fructose and has a fair amount of fiber.

A medium potato contains around 4 grams of protein and only a quarter gram of fat. Although quite low in protein and fat, potatoes do have some nutritional value as they are a good source of Vitamin C, Folate, Vitamin B1, B2, B3, B5 and B6. They are also a good source of magnesium, phosphorus, iron, potassium, copper and manganese, making them a good source of vitamins and minerals when compared to other high carb foods.

The body requires vitamins and minerals to convert our food into fuel that our bodies can use and so foods that have these vitamins and minerals can be considered nutritious since they provide these nutrients and don't drain our own stores. Potatoes consisting of mostly carbohydrates require the use of Vitamin B1, B2, B3, B5 and magnesium to convert into fuel we can use. Since potatoes also provide these nutrients, it is a good food choice when we are looking to include some carbs in our diet.

Vitamin C is a strong antioxidant

Firstly, a deficiency in Vitamin C causes a famous condition called scurvy which starts subtly, but can lead to depression, confusion, internal bleeding of muscles and joints, infection, shortness of breath, fever and many other symptoms. This happens rarely nowadays and usually from a diet of highly refined and processed foods.

Vitamin C has important functions in the body, primarily as a cofactor for enzyme reactions such as for the production of norepinephrine, collagen and carnitine. It also acts as an important antioxidant in cells and plasma which work to prevent damage to DNA, protein, fats and low density lipoproteins (LDL). As a result of this, it helps prevent and lower inflammation in the body.

Vitamin B6 allows our body to use protein

Vitamin B6 is an essential nutrient that we must obtain from diet since we cannot synthesize it ourselves. Vitamin B6 is the generic name and it includes different forms. In animal foods, B6 comes in the form named pyridoxal 5′-phosphate (PLP) and is known to be more bioavailable to humans since this is also the active form in the body. The form obtained from plants is pyridoxine 5′-phosphate which is inactive in the human body and the liver takes an extra step to convert it into a usable form. Vitamin B6 serves as a cofactor for 150 enzymes in the human body which mainly involve protein reactions which degrade and synthesize amino acids.

In studies, a low Vitamin B6 status in the body is associated with increased inflammation and lower immune function. Although deficiency is rare in developed countries, low circulating Vitamin B6 is generally reported in users of oral contraceptives, certain drugs such as antacids and anti-inflammatory drugs, in smokers, people with celiacs disease and diabetes.

Potassium is essential all the cells in our body

Potassium works together with sodium to create a gradient for cell membranes in all cells which is critical to proper cell function. Not very much is known about the bioavailability of potassium other than it is 90% excreted in the urine, 10% in the feces and minor amounts in sweat. Potassium levels and intake affects people with high blood pressure, utilization and control of glucose in all people. An obvious symptom of low potassium in the body is muscles cramps during exercise.

In a relevant study of different potato foods comparing non-fried white potatoes, french fries and a potassium supplement, they found that all sources were equally good sources of potassium (r).

The general rule of thumb to reduce antinutrients in potatoes is to peel the potatoes and cook them. High heat will generally destroy a lot of the antinutrients. Soak or boil potatoes to allow the antinutrients to leech out into the water.

Lectins may irritate and damage the gut

Potatoes are high in lectins which are concentrated in the peel. They are proteins found in all animals, plants and microorganisms. In terms of food, plant lectins are considered to be an antinutrient due to their toxicity and their ability to prevent the body from absorbing certain nutrients. Although there are still many unknowns about how lectins work, at a certain amount they can damage the gut wall causing inflammation and produce symptoms of diarrhea and vomiting. A famous lectin found in our wheat is gluten. For potatoes, the best way to minimize ingestion of lectins is the remove the peel.

Oxalates may lead to kidney stones and mineral deficiency

Potatoes are high in oxalate and a medium potato contains approximately 59mg of oxalate. Oxalates bind with minerals such as calcium and magnesium which can accumulate in organs and form crystals. Kidney stones are the most common occurrence of this but oxalate crystals can be found in many other organs such as the thyroid. The body will handle most of the ingested oxalates and only about 2% to 10% is absorbed. However, with all the high oxalate foods that we can eat everyday, it is very easy to eat enough oxalates which cause their accumulation in the body. Sally Norton, MPH has a great presentation about oxalates for those who want to further understand the risks with oxalate consumption

Phytates prevent mineral absorption

A medium potato contains approximately 100mg of phytates. Although potatoes only contain a moderate amount of phytates, it is easy to eat a lot of potatoes which add up. Cooking potatoes well, will reduce the amount of phytates. Phytates are found in most plant foods and they bind strongly to minerals such as iron, zinc, and calcium. When phytic acid is bound to these minerals in the gut, it prevents absorption making it inaccessible to us. High doses of phytates from food can have a profound effect, preventing up to 82% absorption of those minerals from the given meal (r).

Solanine and Chaconine are natural pesticides

As a member of the nightshade family of vegetables, potatoes are high in glycoalkaloids. These are used by the plant in the stems, leaves and tubers as a defense chemical to kill pests. High doses are toxic to the human body where it interacts with mitochondrial membranes triggering cell damage and even cell death.

Potatoes should be stored in the dark as exposure to light will naturally cause the potatoes to produce solanine and chaconine. When potatoes turn green, this is a good indicator that there are alot of these pesticides present. The chemical is usually concentrated in and close to the peel. Also potatoes will taste bitter when there is a lot of this chemical present.

Green or bitter potatoes should not be eaten. General home cooking methods don’t significantly affect the amount of solanine and chaconine in potatoes. Peeling the potatoes will reduce the amount, but there will still be some in the flesh of the potato.

French fries you have when you go out to eat at restaurants and fast food are definitely unhealthy. This is mainly due to the fries being fried in constantly heated and reused vegetable oils which are high in polyunsaturated fat and are prone to oxidation. Studies have shown that these oils produce high amounts of toxic lipid oxidation products such as acrolein which can also be found in cigarette smoke (r, r).

A healthier way to have french fries would be to cook them in a more heat stable fat such as coconut oil, butter or tallow which are high in saturated fats. Air-frying them may also help reduce the amount of fat oxidized by high heat.

Although one downside to french fries are that when carbs and fats are combined, they become hyperpalatable as it will trigger our brain’s reward centers making it very easy to over consume.

On a ketogenic diet, we are trying to keep insulin low to allow for maximum fat utilization. Potatoes are made up of 90% carbohydrate calories and would cause an insulin spike. A high enough spike would essentially stop ketosis and fatty acid metabolism and cause the body to focus on utilization of glucose. Focus on nutrient dense foods rich in protein and fats for maintaining an optimal hormonal balance while focusing on weight loss.

If you are experiencing some brain fog then you can try avoiding potatoes. Potatoes are a high glycemic index food which will cause a fast and high rise in blood sugar and insulin that the pancreas will release in response. When this happens often times the insulin released will be too much and it will overcompensate by lowering your blood sugar below normal levels and even possibly triggering reactive hypoglycemia. This in turn will cause brain fog while your body fights to stabilize the blood sugar levels.

If you want to eat potatoes but avoid the side effects, you can try the following:

1. Eat a lower quantity of potatoes
2. Take a tablespoon of vinegar in a glass of water before eating the potatoes (r, r, r)
3. Carbohydrates convert into sugar and enter your bloodstream. In order to handle this, your pancreas releases a lot of insulin to bring down the sugar level and more often will bring it down too much causing brain fog. Do glycogen depleting exercise before eating the potatoes or go for a walk after your meal to allow your muscles to better uptake post meal blood sugars (r).
4. Cool the potatoes and eat them cold. Some of the starches in cooled potatoes become resistant starches which act like fiber and cannot be digested (r).
5. Eat the potatoes last, after eating your protein and fats. This will slow down the absorption of starch in the potatoes.

Potatoes are made up of primarily starch which is a carbohydrate. It then breaks down into glucose and converted into glycogen which is stored inside your muscles to provide them with energy. Starchy foods such as potatoes are a good tool to use to quickly replenish muscle glycogen stores.

Avoid potatoes for keto fat adaptation

In the context of the ketogenic diet, after fat adaptation, you muscles can efficiently use both fatty acids and glycogen as fuel. It will then mainly use fatty acids and spare glucose for the most intense movements.

Potatoes can supply some extra energy in the form of glucose for your workout. It is not a good idea to use too much carbohydrates, especially while training to become fat adapted on a keto diet. Fat adaptation allows your body to efficiently metabolize both fatty acids and spare glucose for when and where you need it most. Eating too many carbohydrates will cause your body to lower fat metabolism producing fewer ketones while focusing on glucose metabolism. Being efficient at fat metabolism and glucose metabolism is called metabolic flexibility and provides numerous advantages, making your largest store of energy available to you at all times.

Refill your muscle glycogen stores with potatoes

Once fully fat adapted and have reached your weight goal, feel free to use potatoes to refill your glycogen stores. A good time to do this is generally after a workout, or if you need to, during an extended workout session.

Generally, after a workout, 100 grams or less of carbs is sufficient to refill your glycogen stores. This is still considered low carbohydrate and would most likely stay in ketosis if that is one of your goals.

Do I need carbohydrates to build muscle?

Muscles grow through the activation of muscle protein synthesis which do not require any carbohydrates. This process will use amino acids broken down from protein. Therefore, eating some protein, especially from a highly bioavailable food source such as from meat will increase performance while maximizing muscle building. Although carbohydrates will help in a minor way where insulin is increased causing your muscle cells to take up the amino acids from your food, however, since protein will also cause insulin secretion, carbohydrates become unnecessary.

Eating high glycemic carbs to raise insulin will cause muscle cells to absorb amino acids from the bloodstream leaving less competition for tryptophan to cross the blood brain barrier. This will supply your brain with more tryptophan which will allow your brain to convert it to the serotonin and melatonin your brain needs to regulate mood and sleep. If you are finding it harder to cope with stress during the day, this strategy may help (r, r, r).

Potatoes can be included in a healthy diet when properly prepared and not eaten in excess without exercise. From this article, we have also learnt that they can be used to quickly recover from an intensive workout or improve sleep. However, when we are doing the ketogenic diet for weight loss and keto fat adaptation we should avoid potatoes until we have reached our weight target or when we see that we are efficiently burning fat.