Bowl of keto diet friendly foods

Keto Diet Pros and Cons: A Registered Dietitian’s Perspective

If you have ever looked into diet plans for weight loss, you have probably come across the keto diet at some point. A lot of people are curious about the potential benefits of following this diet, but they don’t really know where to look. 

And if you have diabetes, there are unique challenges to consider with a very low carb meal plan like the keto diet. If you are someone living with type 2 diabetes and you want to know about the keto diet pros and cons, you are in the right place. Read on!

In this post, we will discuss how the keto diet works and the benefits and risks of the keto diet for someone with diabetes. We will also review other options that you may want to consider before jumping full force into a drastic diet change.

Brief History of the Keto Diet

Although it may seem like the keto diet is a relatively new fad, physicians have used very low carb diets for over a century in the treatment of various disorders. Treatment of seizures in epilepsy, for example (1). 

The keto diet has become a trending topic in recent years as a quick solution for dramatic weight loss. These days, it seems like everybody and their mother is following the keto diet.

What is the Keto Diet?

So what is this magic meal plan? The keto diet, also known as a ketogenic diet, is a very low carbohydrate, high fat eating pattern. 

All of the foods that we eat are made up of three different macronutrients or macros (building blocks of food that give us calories). These are carbs, fat, and protein. 

In a normal, healthy diet, the USDA Dietary Guidelines for Americans 2020-2025 recommend 45-65% of calories to come from carbs and 20-35% of calories from fat.

In contrast to this, a very low-carbohydrate diet like the keto diet is typically as low as 5-10% of calories from carbs and as high as 75% of calories from fat (2). 

And this pattern is technically a modified keto diet. The macronutrient distribution for the classic keto diet is even more strict! More like 4% from carbs and 90% from fat (1).

Macronutrient distribution of keto diets vs USDA recommendations

How does it work?

Now that we know the basics of what a ketogenic diet looks like, how does it work to promote quick weight loss? We need to first understand the body’s normal process for getting energy from our food.

Every cell in your body prefers to use carbs for energy. If there are carbs present in your diet, your body will use them first.

But what happens to that process when you essentially eliminate carbs from your diet? Well, your body has to find another way of obtaining energy. 

Humans are generally very good at surviving. So, in the absence of carbs, your body learns to start breaking down fat in search for an alternate source of energy. A byproduct of this process is called ketones, or ketone bodies. And these ketones are now used as a new source of energy (3). 

Once your body has switched over to fat as its primary energy source, it is said that you are in a state of ketosis. This is because of the ketones that your body is producing.

In order to stay in ketosis, the ratio of fat to protein to carbs must remain consistent or your body can easily switch back to using carbs for energy. Remember, your body prefers carbs.

Before we get into the keto diet pros and cons, I want to quickly point out the difference between nutritional ketosis and diabetic ketoacidosis. 

Nutritional ketosis is when you force your body to use ketones instead of glucose by changing the macros that you put into your body (more fat, less carbs). This process increases the amount of ketones in the blood by a very small amount.

Diabetic ketoacidosis (DKA) can happen in people with diabetes who begin using ketones for fuel as a result of high blood sugar levels and the inability to use the glucose for energy. This reaction can cause very high amounts of ketones in the blood and can be dangerous (2).

WARNING: Drugs in the medication class SGLT2 inhibitors (Invokana, Farxiga, Jardiance, etc.) have been associated with a risk of DKA without significantly high blood sugar. This makes it more difficult to recognize.

Several cases have been connected to starting the keto diet (4, 5). If you are currently taking one of these medications, it is critical to discuss with your doctor before starting a very low carbohydrate diet.

Keto Diet Pros and Cons

Keto diet pros and cons


Quick Weight Loss

This is by far the most well-known benefit of the ketogenic diet. And it is true that many people see a significant drop in their weight after getting their body into ketosis. 

Researchers aren’t entirely sure what the cause of this is, but often cutting out carbs can cause a quick loss of water weight. Glycogen (the storage form of carbohydrates) holds on to water. So when you force your body to get rid of your stores and start using fat for energy, you also lose a good amount of water. 

The bad news about this is you are likely to gain some of that weight back if and when you decide to return to a normal diet plan (2)

Improved Insulin Resistance

Improved insulin resistance is a very appealing advantage to the keto diet for people with diabetes. By drastically reducing your intake of carbs, you are also taking some of the stress off your body’s blood sugar regulation system (7).

If your pancreas is no longer producing adequate insulin, eliminating carbs can allow your pancreas to rest and potentially regain some of its function.

When it comes to insulin resistance, the weight loss that comes along with the keto diet can help your body use your insulin better and therefore lower your blood sugars.

However, the pancreas and insulin is not the only body system that is involved in hyperglycemia (high blood sugar). Researchers have discovered up to eleven different processes that don’t work as well as they should in someone with diabetes.

Better Food Choices

It is entirely possible to technically follow the keto meal plan, while eating an unhealthy diet. However, if done correctly, the keto diet does have the potential to improve the nutrition of your food choices. 

You will most likely cut out a lot of processed foods. And the restrictions involved in the keto diet encourage home-cooked meals, since it can be difficult to eat at a restaurant when you eliminate most of your carbohydrate foods.

Meal Satisfaction

Now this one might be a bit of a surprise to you. Many people have noticed that they are more satisfied at their meals when following a very low carb, high fat meal plan. 

Fat takes longer to digest than carbs, meaning it will fill you up faster and stay in your system for longer. This has been found to prevent overeating and eliminate cravings, likely contributing to weight loss.

Potential Treatment for Health Conditions

I mentioned earlier that the keto diet was originally developed as a treatment for epilepsy (1). This is the main medical condition that the keto diet is officially recommended for, but new research is being conducted all the time! 

Studies suggest that a very low carb, high fat diet may have protective benefits in conditions like multiple sclerosis, cancer treatments, autism spectrum disorders, Alzheimer’s dementia, and even Parkinson’s (2). 


Sure, there are several very intriguing benefits to the keto diet, but let’s not forget to examine the potential risks.


One of the biggest cons from a Registered Dietitian’s perspective is that this super strict meal plan is not sustainable. 

My goal when I work with clients is to help find a meal pattern that you can keep up long term. Sure all of the benefits sound really great, but what good will they do you if you quit after a few weeks and gain the weight back? 

It is hard enough to follow any meal plan, but the keto diet is especially hard to maintain in order to remain in ketosis.

Risk of Hypoglycemia

The keto diet also comes with a risk of hypoglycemia (low blood sugar) for people who have diabetes (2). You are especially at risk if you are taking any medications that lower your blood sugar. These would include insulin or a category of medications called sulfonylureas (ie. Glipizide, Glimepiride, or Glyburide). 

When you take a medication that actively removes sugar from your blood, and you don’t replenish that sugar, it could be dangerous.

Nutrient Deficiencies

Again, from a Registered Dietitian’s standpoint, nutrient deficiencies are a huge concern with the keto diet. Any meal plan that cuts out entire food groups is likely to leave you missing vitamins and minerals. And the ketogenic diet essentially cuts out all fruit and grains, as well as some dairy and protein sources. 

Just think about all of the nutrients that you could be missing. Some common deficiencies are vitamin A, vitamin C, phosphorus, magnesium, and the B vitamins (8).

Food Obsession

This con may not be a risk for everybody, but people who are prone to obsessing over their food choices would probably not do well on the keto diet. 

Because it is so strict, this meal plan requires constant consideration of the type and amount of the foods that you are consuming. This can easily lead to food obsession and various forms of eating disorders.

Heart Health

By nature, the keto diet is high in fat. However, there are healthier fats and less healthy fats. If most of your fat is coming from animal products like red meats, you will be consuming a large amount of saturated fats (AKA unhealthy fats).

The reason saturated fats can be considered unhealthy is that they can lead to high LDL cholesterol (“bad” cholesterol), low HDL (“good” cholesterol), and an increased risk of heart disease (9). 

Kidney Health

Because the keto diet results in the production of ketone bodies, these ketones also need to be eliminated after they are used for energy. This is the job of the kidneys. 

Any time you have excess amounts of something in your blood, it creates extra work for your kidneys as they try to process it out. The kidneys can also be at risk due to dehydration that can happen as your body eliminates your stored carbohydrates. Remember that glycogen holds on to water.  

There have also been some reported cases of kidney stones as a result of following the keto diet (10).

Gut health

The gastrointestinal tract (GI tract) can also be impacted by a drastic diet change like the keto diet. 

Many people experience altered bowel movements: diarrhea due to the increased fat intake and constipation due to the lack of fiber-filled foods. Neither one of these is good for gut health. 

In addition, eliminating fresh fruits and whole grains removes much of the prebiotics in our diet (insoluble fiber that our good gut bacteria feeds on). This can lead to an imbalance of “good” to “bad” gut bacteria (6).

Final Thoughts

If you are considering following this diet, it is important that you weigh all of the keto diet pros and cons before making a decision. It’s always best to consult with your doctor before starting any new meal plan. They can help you determine if there are any medical concerns that you may be at risk for.

Recommendations From a Registered Dietitian

Personally, I don’t usually recommend the keto diet for most people because I would rather you to consume a balanced diet and enjoy foods from all food groups. I prefer the philosophy of best-selling author, Michael Pollan: “Eat food, not too much, mostly plants.” 

There are many other diet plans out there that have had good results for weight loss and blood sugar control without the super strict elimination of several food groups.

A couple of my favorite meal patterns are the Mediterranean Diet and a whole foods plant based diet. These both have good balance and focus on choosing fresh fruits and veggies, high fiber grains, lean proteins, and heart healthy fats.

If You Decide to Follow the Keto Diet

However, if you do decide to go ahead with the keto diet after considering all of the pros and cons, there are a few things someone with diabetes should consider:

Do it properly. 

By this, I mean make sure that you are choosing healthy, nutritious foods that are nourishing your body. Don’t just survive on fried foods and bacon. 

Include plenty of fresh veggies, legumes, nuts and seeds, and other heart healthy fats. These foods will give you vital nutrition that you might otherwise be missing.

Monitor blood sugar closely.

Cutting out carbs can put you at risk of low blood sugar. But removing your body’s preferred energy source could also trick your liver into producing more glucose. Read more about this potential increase in hepatic glucose production here.

You may need to check your blood sugar more often when following the keto diet to monitor how your body is reacting. For tips on strategically monitoring your blood sugar, try checking in pairs.

Consider a short term diet change.

If you follow the keto diet for a short time period (4-6 months), you can gain the benefits of weight loss without restricting your nutrition long-term. 

Consider a transition back to a low to moderate carb diet. You will want to gradually reintroduce carbs back into your diet in order to avoid gaining the weight back as your body comes out of ketosis.

Just be aware that there is little research on the risks or benefits of following the keto diet long term.

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