Medically reviewed by Shahzadi Devje, Registered Dietitian (RD) & Certified Diabetes Educator (CDE)
Here at Desi~licious RD Inc. I believe that you should have access to the best available evidence to help guide your dietary choices. In light of emerging research and a change to clinical practice guidelines, both in Canada and the US — I have updated this article.
You've probably heard of the ketogenic diet – or "keto." It's been rising in popularity as a means to lose weight and keep blood sugar levels in check. In this comprehensive guide, we address the pros and cons of the ketogenic diet.
Eating a healthy, balanced diet is one way to keep your blood sugar and insulin levels within a healthy range, especially for Type 2 diabetes. Most dietary guidelines recommend limiting sugary foods and reducing portion sizes of carbohydrate-rich food, like bread and pasta, which also increase your blood sugars.
If you have Type 2 Diabetes and are struggling to maintain normal blood sugars, you may find yourself wondering which foods are safe to eat and whether you'll be able to ever eat sweets or carbohydrates again!
With so many seemingly compelling health claims in the media these days – you know the ones with testimonials to the tune of "I've lost 15 lbs in 2 weeks doing keto and my sugars are below 6 mmol/L", naturally you may be tempted to try the keto diet for yourself.
Before we dive in and break it down, let's recognize reduced-calorie, low-glycemic index, high-protein, Mediterranean and DASH (Dietary Approaches to Stop Hypertension) Diets have also shown to result in weight loss and improved heart disease risk factors. They, too, are effective at lowering blood sugars and reducing the need for diabetes medications.
What is the Ketogenic Diet?
If you're wondering what keto's main rules are, it's a very low carbohydrate, high-fat diet. Your ketogenic diet plate includes mostly fat (about 80% of total calories), some protein (about 15% of total calories), and minimal carbohydrate (around 5%).
How Many Carbs On The Keto Diet Can I Eat?
Typically, the keto diet carb limit is less than 50 grams of total carbohydrates daily. In fact, it can even stretch to as low as 20 grams a day.
Ketogenic diet food list examples include:
High carbohydrate foods, like grains (bread, cereal, pasta, rice, oats, etc.), potatoes, beans, milk (dairy), sweets, and most fruits, are eliminated or rigorously limited on a ketogenic diet.
If this sounds restrictive, it's because it is!
Although the ketogenic diet may seem trendy, it was originally created in the 1920s to help manage seizures in epilepsy patients.
How To Get Into KETOSIS?
In normal human metabolism, glucose from carbohydrate-containing foods, like grains, beans, potatoes, and fruit, is the main energy source for your body. It's also the preferred energy source for your brain.
When you eat lots of fat, with little to no carbohydrates, this prompts your body to switch to a type of metabolism called 'ketosis.'
In ketosis, dietary fat and stored body fat are broken down and converted into ketones by the liver. Ketones are then used for energy instead of glucose.
What Are The Pros And Cons Of The Ketogenic Diet?
PRO: Weight Loss
Since your fat stores are broken down in ketosis, those who follow a very low carbohydrate keto diet indeed experience rapid weight loss. Several studies have found participants who follow a keto diet experienced greater weight loss than those following low-fat diets.
PRO: Reduced Triglycerides, Blood Pressure & May Change LDL particles
In addition to weight loss, many studies have found that following a keto diet reduces triglycerides and diastolic blood pressure. Yes, these are crucial factors in determining your risk of heart disease.
When it comes to the ketogenic diet and cholesterol research, an increase in HDL (High-Density Lipoprotein) and LDL (Low-Density Lipoprotein) cholesterol has been reported in keto dieters. While you might think that LDL is all "bad" and leads to heart disease — it's not that simple.
Aside from the total amount of LDL cholesterol being of concern, it's also the type and size of the LDL particle. Research indicates that those whose LDL particles are predominantly small and dense have a significantly greater heart disease risk. In contrast, the large and fluffy type of LDL may actually be protective. It's a similar story with HDL cholesterol. Commonly perceived as the "good" cholesterol, HDL acts as a scavenger and removes the harmful LDL cholesterol by transporting it to the liver for processing. But what we're finding out is that the size of the HDL particle size is significant.
This research indicates that women with larger HDL particles had a higher risk of atherosclerosis than those with smaller HDL particles.
Regarding the weight loss studies cited above, I could not find information on the ketogenic diet's effect on LDL and HDL particle subclasses. However, this study showed that a low carb ketogenic-type diet results in a shift from small dense LDL to large and buoyant LDL — which could lower cardiovascular risk. But, this was a small study, and I struggled to find robust evidence.
It turns out that this small study noted improvements in lipid subclasses in both the "reduced carbohydrate" and "reduced fat" groups. Additionally, this 6-month randomized controlled trial in diabetes and metabolic syndrome patients showed no difference between a low carbohydrate diet and a conventional diet on lipoprotein subclasses or inflammation markers.
PRO: Less Hunger & Controlled Appetite
Besides body fat stores breaking down, weight loss on a ketogenic diet occurs for a couple of different reasons:
- Participants in several research studies reported feeling less hungry and eating less food overall, likely because fat and protein fill you up more than carbohydrates do.
- High amounts of ketones in your body may also suppress the hormones responsible for controlling appetite.
PRO: May Improve Blood Sugars
Several studies have found that a very low carbohydrate "keto-style" diet promotes a more significant reduction in blood sugars (as measured by HbA1C) and triglyceride levels. We've also seen more weight loss when compared to other diets.
Updated recommendations from the American Diabetes Asociation (ADA) state, "...research indicates that low-carbohydrate eating plans may result in improved glycemia and have the potential to reduce antihyperglycemic medications for individuals with type 2 diabetes."
The studies reviewed by ADA dropped the carbohydrate intake of participants to less than 40 grams per day to induce nutritional ketosis. In another non-randomized, controlled study, participants limited their carbohydrate intake to fewer than 30 grams per day. This appeared to be highly effective in improving blood sugar control and weight loss in adults with type 2 diabetes while significantly decreasing medication use. Patients underwent continued nutrition counselling and medical assistance.
Changes in blood sugar levels can occur quickly on a ketogenic diet. If you're taking blood sugar-lowering medication, it's important to work with a healthcare professional and Dietitian while on the diet to make sure your levels don't drop too much – as this can be just as dangerous as being too high.
While quick weight loss and lowered blood sugar levels may sound very appealing to you, there are some concerns about the keto diet's safety and sustainability.
Keto Diet Cons:
CON: May increase the risk of death — from any cause
This 2018 study of 24,825 participants of the US National Health and Nutrition Examination Survey (NHANES) revealed a negative link between low carbohydrate diets and total and cause-specific death, based on individual data and pooled results of previous studies over a decade. Professor Banach, the study author, said, "The findings suggest that low carbohydrate diets are unsafe and should not be recommended."
The study divided Americans into four quartiles, from lowest- to highest-carb diets. They noticed that participants in the bottom 25% — the ones who ate hardly any carbohydrates, had a 32% greater risk of death from any cause than those with the highest intakes of carbohydrates.
Additionally, the low-carb bunch had a 51% higher risk of death from heart disease and a 35% increased risk of dying from cancer relative to the top 25% of carb eaters.
And it didn't stop there.
The data was then compared with dietary data of 447,506 people worldwide and observed that on the whole, those on low carb diets had a 15% higher risk of dying. Interestingly, those who ate a moderate amount of carbohydrates were more likely to live longer than low-carb or high-carb dieters.
CON: Hurts The Environment
Typically the ketogenic diet is heavy on animal fats and protein, which can have adverse environmental impacts. We know that meat products are the most significant source of methane, which influences global warming. According to the World Resources Institute, dairy products and poultry don't contribute nearly enough greenhouse gas emissions as red meat. Still, they are detrimental to the environment than plant-based items such as lentils and beans. Dairy is ranked as "medium" regarding its impact on greenhouse gas emissions, which add to climate change.
But let's not forget that even plant foods can harm the environment. For example, palm oil, a high-fat source permitted on keto, has caused rainforests' deforestation worldwide.
CON: Benefits May Be Temporary
Most of the studies on the ketogenic diet follow small groups of participants for a few weeks or months, meaning the long-term effects of eating high fat and low carb diet are largely unknown. One study found weight loss from a ketogenic diet seemed to plateau after one year.
CON: Highly Restrictive
A ketogenic diet limits the types of foods you can eat, which might make it hard to stick to. Avoiding carbohydrate foods may leave you feeling like you're missing out at mealtimes and create anxiety around eating. As you've likely experienced, this can be very emotionally draining. Generally speaking, for most people, restricting carbs means boosting their intake of meat and other proteins while relinquishing important high-fibre, carb-rich foods like beans, carrots, bananas, lentils and chickpeas.
CON: Not Enough Nutrient-Dense Foods
Avoiding fruit, some vegetables, grains and legumes on the keto diet mean you might be lacking fibre, key vitamins and minerals, and missing out on important inflammation-fighting antioxidants.
CON: Nearly impossible To Sustain
With the level of restriction and the amount of dietary change required to follow a ketogenic diet, it's not surprising that it's too hard to sustain. This echoes one of the primary reasons the US News and World Report ranked the keto diet as one of the five worst on their list.
CON: Keto Flu
Your body needs some time to adjust when switching from carbs to mostly fat. You might experience uncomfortable side effects, like fatigue, headaches, brain fog, and bad breath. (Yep, it's keto breath smell – think rotting apples, from acetone!)
CON: Could Mean A High Saturated and Trans Fat Intake
Since the focus in a ketogenic diet is on fat, your intake of saturated and trans fats may increase. But, let me point out something that often gets overlooked: eating fried mozzarella sticks is far from a "good healthy fat" choice compared to using a tablespoon of virgin olive oil to saute your veggies.
Try my deliciously easy Grilled Mixed vegetable recipe – the perfect side dish for your meal!
Remember, not all fats are created equal! And eating too many of these types of fats promotes inflammation and increases the risk of heart disease – something people with diabetes are already at an increased risk for.
Whether you decide to try the ketogenic diet or not, enjoying healthy, unsaturated fats from nuts, seeds, avocados, olive oil, and fish are your best bet for a healthy heart.
CON: Risk of Lipotoxicity — Causing Insulin Resistance & Type 2 Diabetes
Did you know that one of the primary causes of insulin resistance – the hallmark of Type 2 Diabetes, is 'lipotoxicity'?
This metabolic syndrome is when there is an accumulation of excess fat in the body's tissues where it shouldn't be – like the liver, heart, pancreas, and muscles. Lipotoxicity, in turn, is thought to be exacerbated by a very high dietary intake of saturated and trans fatty acids — a concept that has been well-documented by Dr. Michael Greger, MD. Therefore, a diet that reduces inflammation and cell damage is key to preventing toxic fat!
Final Thoughts On The Keto Diet For Type 2 Diabetes
It's been shown — time and time again — that you do not need to completely cut out carbs to manage diabetes effectively. And diets that include plenty of plant foods and whole, unprocessed grains, much like in the Mediterranean diet, have been well studied and are linked to increased lifespan and decreased rates of diabetes, heart disease, and cancer.
If you're trying to keep your blood sugar levels in check, simply reducing the number of refined carbohydrates you eat can help immensely. By 'refined,' I mean the processed and packaged varieties, like breakfast cereals, most crackers and pretty much any sugar-laden snack food!
Including plenty of nourishing, nutrient-dense foods, like fruits and vegetables, has many health benefits, including decreased inflammation, preventing constipation, and less heart disease risk.
Although there seems to be a short-term advantage of the ketogenic diet for weight loss, the advantage seems to "shrink" at the one year mark. No significant difference in weight loss was observed at one year between a low carbohydrate diet and a conventionally "healthy, balanced" diet.
There's also insufficient research to make firm conclusions about the ketogenic diet's long-term effects on weight loss and other health parameters. Plus, the long-term safety is yet to be determined.
Let me be clear, though – I don't hate it! But, isn't it interesting how the very foods that have shown time and time again to lead to less diabetes, less heart disease, less cognitive decline, and less cancer are the ones being excluded in the keto diet? The bigger question we should be asking is: does the keto diet confer an advantage over other dietary approaches – specifically aimed at weight loss while managing diabetes? And — can we afford to ignore its impact on the health of our planet?
In my opinion, and based on the current research, I don't think so.
Real people living healthy, happy lives are proof of this, which goes beyond the research. It's real-life – those in the so-called "blue zones" eat unrefined whole grains, healthy fats, high-quality protein, AND they live the longest in the world, not to mention have the least disease.
Diabetes Starter Kit: It's time for a 180
Change the habits that don't serve you and adopt new ones that propel you to health and vitality. In this FREE Starter Kit, I show you exactly what a diabetes-friendly diet looks like and include my tried and tested food tips that have shown to help my diabetes clients stabilize their blood sugars and feel their best – all backed by science.
Shahzadi is an award-winning registered dietitian (RD) regulated by the College of Dietitians of Ontario and certified diabetes educator (CDE), approved by the Canadian Diabetes Educator Certification Board. A YouTuber and notorious foodie, she's dedicated to helping you end your cooking wars, transform your health, and be the best version of yourself! Shahzadi is an on-air nutrition expert for CTV Your Morning and a regular contributor for Global News and other national media outlets.