I review the pros and cons of the Keto Diet and if it leads to weight loss.
I wasn’t planning on writing about the ketogenic diet but that all changed with my recent YouTube video. My girl Abby Langer and I found a hilarious Reddit thread that shared some keto-followers favourite “strange but delicious” keto-friendly meals and snacks. Let’s just say, it was extreme. I was by no means under the impression that everyone on the Keto diet ate that shit. I get why some viewers on youtube maybe thought that and they got PISSED. Like, viciously pissed.
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I decided to share what I ACTUALLY think on all things keto. I want to give you a comprehensive review of the diet so there’s no confusion. At the end of the day, ‘haters gon hate’ but at least I can sleep at night knowing I’ve done my due diligence in whole heartedly giving you all the necessary information around this diet.
Let’s dive in.
What Is the Keto Diet?
If you haven’t already jumped on the keto diet bandwagon, I’ll give you a brief introduction. Basically, the ketogenic diet is a super high in fat (65-75% of your diet is fat), a super low carbohydrate (<5% of your diet) and moderate in protein (15-20% of your diet). Surely, not the most balanced of diets considering Health Canada your diet should contain 10-35% of protein, 45-65% of carbohydrate and 20-35% of fat. So how to you meet that skewed macronutrient distribution? Well, you load up on keto diet staples like meat, fish, butter eggs, cheese, heavy cream, oils, nuts, avocados, seeds and low carb green vegetables. And you cut out all your go-to carb sources like grains, rice, beans, potatoes, sweets, milk, cereals, and fruits. These kinds of restrictive diets tend to make nutrition professionals like dietitians run for the hills but I’m going to give it my honest unbiased account.
dietitian’s keto diet review
Dos and Don’ts of a Keto Diet
Dos: Most proteins are fair game with a keto diet, however it is encouraged to enjoy organic, grass-fed or pasture-raised meats. On a keto diet you can enjoy a variety of protein sources such as whole eggs, fatty fish like salmon, seafood, organ meats, steaks, pork, poultry and more.
Don’ts: While the majority of proteins are okay in a keto diet, any meats or protein sources with added sugars is a no no.
OILS AND ADDED FATS
Dos: Fat makes up a huge part of the keto diet because it’s basically your main fuel. That is why it is encouraged to choose organic and grass-fed whenever possible. Excellent fat sources include olive oil, mayonnaise, coconut oil, butter, lard and other non-hydrogenated or unprocessed oils.
Don’ts: As long as there are no added sugars to the fat source, most fats are fair game.
NUTS AND SEEDS
Dos: Nuts and seeds are the best snack to fuel your day on a keto diet. Excellent sources include almond butter, flax seeds, macadamia nuts, brazil nuts and pecans.
Don’ts: Nuts covered in sugar are a no no.
Dos: Enjoy all of the cheese you would like on a keto diet. On top of that other great dairy sources include whole milk, full fat Greek yogurt and cream.
Don’ts: Avoid yogurts and creamers that are sweetened because they can quickly add to your overall carb count for the day.
FRUITS AND VEGGIES
Dos: To avoid constipation, load up on low carb veggies like kale, spinach, cabbage, mushrooms, green beans and green bell peppers. Some lower sugar fruit options include blueberries, blackberries and raspberries, but eat them sparingly.
Don’ts: Since fruits are high in sugar and carbs, they are usually a no go except for the few mentioned above. Fruits that are usually avoided on a keto diet include oranges, grapes, mangos, apples, papaya, pineapple, bananas, dried fruit and fruit concentrates. Avoid highly starchy vegetables like potatoes, corn, parsnips and yams.
Don’ts: All grains, even whole grains, should be avoided on a keto diet. A high intake of carbs will interfere with ketosis.
BEANS AND LEGUMES
Don’ts: Due to their high starch content, beans and legumes should be avoided.
What is Ketosis?
Ketosis is natural and normal, though arguably not optimal.
Our bodies run well on glucose (carbs)–they give us the necessary energy we need to function on a daily basis. When our body doesn’t get enough glucose (either because we’re cutting carbs too low, OR we haven’t eaten in too long), our body kind of freaks out and looks for other forms of energy to satisfy that role. That’s where the fat comes in. Without carbs, our insulin levels drop and fat is released from our cells. The fat overwhelms the liver which turns it into ketones, our body’s second choice to carbs for energy.
So, to confirm. Yes, your brain CAN function without carbs, but carbs are still your brains favourite good and some brain cells can only use glucose for fuel.
Ketoacidosis in Diabetes
It’s important we distinguish between the process of ketoacidosis seen in type 1 diabetes and this ketosis that so many people on the keto diet are striving for. If someone with diabetes lacks enough insulin and/or does not eat enough carbohydrates, they risk entering a state known as ketoacidosis. For those with uncontrolled diabetes, this can increase the levels of ketones in the blood, increasing the acidity of the blood, and potentially leading to a coma or even death. In ketosis for a healthy individual, the level of ketones in the blood never reaches these crazy high levels so it’s generally safe for the average healthy individual.
Bottom line: Ketosis is not ketoacidosis and is generally safe for most healthy people.
Keto Diet History
So where did the ketogenic diet come from? Interestingly enough, this fad diet didn’t spark from a celebrity endorsement or some guy missing a medical license. There’s evidence of the keto diet being used back in the early 1920s to treat severe childhood epilepsy and it’s still being used today for that purpose. Research suggests that the production of ketones may influence neurotransmitter activity in neurons allowing for a reduction in seizure attacks.
A recent Cochrane Review demonstrated a 30-40% reduction in seizures compared with non-keto diet controls. One thing to keep in mind, however (which is a theme when discussing the keto diet) is that it’s generally difficult to adhere to and difficult to tolerate for a lot of people. In other words, people go on it and then come off it pretty damn quick.
Once the medical community acknowledged the keto diet’s effectiveness in reducing seizure episodes, they decided to look further and study its impact on neurological diseases in general. Neurological diseases share a common problem – a deficiency in energy production. Ketones provide that energy for normal brain cell metabolism, and may even be a more efficient when the body is in starvation mode. When patients were put on the keto diet, the number of mitochondria (energy powerhouse) in brain cells increased. Ketones may also act as an antioxidant by inhibiting the formation of reactive oxidant species, which is why they may have promising effects in the treatment of certain cancers in conjunction with chemotherapy.
A 2017 mice study from the University of California found that a ketogenic diet (90% of calories from fat) lead to an increased life span, memory and motor function. Researchers observed a 13% increase in median life span when compared to a high carb diet.
Really exciting stuff, actually. Let’s look at a few other specific neurological diseases and the impact of the keto diet there.
In a study, Alzheimer’s patients fed with a ketogenic diet experienced improvements in their symptoms, which again may be due to the improved mitochondrial function. In another study, patients with Alzheimer’s were given a drug with ketones and after 90 days, they experienced improvements in cognitive function.
In a pilot study, five out of seven patients trialed a keto diet for 28 days and showed marked reduction in physical symptoms. Parkinson’s attacks our human nervous system, partially as a result of an abnormal accumulation of a protein called alpha-synuclein. Research suggests that a ketogenic diet may reduce the associated cognitive and motor symptoms.Obviously, we need more research here but its an exciting finding.
This also may be too premature, but an animal study found that the keto diet delayed motor neuron death and showed MS improvements, however it did not increase the life span of the subjects. In an exciting 2016 study, the ketogenic diet improved the quality of life, physical health and mental health of patients living with MS.
Cardiovascular Health vs keto reviews
What about heart health and the keto diet? Previous older schools of nutrition would purport that a diet rich in fats (specifically saturated fats) would be detrimental for heart health. However, more recent research suggests that saturated fat is not as bad as previously believed. There is actually a tiny little bit of evidence that a keto diet may improve triglyceride, HDL and LDL levels. Like here and here. An even more recent study found that a keto diet improved triglyceride, HDL and LDL levels. We’ll definitely have to wait to see how that research unfolds.
Type 2 Diabetes vs ketogenic diet review
There have been many attempts at studying the link between type 2 diabetes and the keto diet. In one study, a strict low-carbohydrate diet was administered in obese patients with type 2 diabetes. After 14 days of being on the diet, the glucose levels of participants normalized. Their hemoglobin A1C decreased from 7.3% to 6.8% and insulin sensitivity improved by 75%. Some of this study’s limitations include the short duration, the small sample size and the weak control group. In another study, 84 obese patients with type 2 diabetes were randomized to either a low-carbohydrate keto diet or a low-glycemic reduced calorie diet. At the end of the study, both groups experienced improvements in glycemic control. However the low carb keto group had greater improvements in hemoglobin A1c and higher HDL levels compared to the low-glycemic group.
A more recent 2017 study in the journal of Nutrition and Diabetes found that a low carbohydrate ketogenic diet for 12 months led to greater reductions in HbA1c and body weight. These results suggest that low carbohydrate interventions may be effective at improving glucose control.
Cancer vs keto diet review
There is exciting research on the role of a keto diet as a form of treatment for cancer. In one study, the use of a keto diet on patients with advanced cancer was deemed safe, and some evidence suggested it played a role in stabilizing the disease or resulting partial remission. In another study, the keto diet was used as a form of therapy for patients with malignant brain cancer. The study found that the keto diet may carry anti-tumor effects when administered in experimental animal and human brain tumors. The researchers believe this may be due to the reduction in calories. This reduces the circulating glucose needed for tumor growth. It is still unsure whether a keto diet per se plays a role in this or simply calorie restriction. All of this is to say that the research is preliminary, however still promising.
Sports Performance vs ketosis review
In the sports nutrition field, we discuss the importance of timing carbohydrate and fluid intake on improving sports performance. For some time now, research has been looking at the role of very low carbohydrate diets on sports performance. Trailblazers in keto and sports performance research like Dr. Stephen Phinney have been conducting studies in this area since the 80s. In one of his studies, the glycogen stores of cyclists on a keto diet were not completely depleted and lipid oxidation was increased. Researchers concluded that the body was able to adapt to the lack of carbohydrates and preserve what was needed to use the fat as fuel. However, based on the VO2 max breath test, since the body was attempting to preserve the carbohydrate during the exercise, it appears that the intensity of the exercise was limited.
In a more recent study, off-road cyclists following a keto diet experienced small improvements, but still not significant enough to make strong conclusions.
The only difficulty with some of these studies is that they tend to have small sample sizes, like this one that only has five cyclist participants and the data was largely skewed by the fact that only ONE cyclist experienced a large enhancement of exercise capacity after the keto diet. Their studies also tend to be short term. Back in 2014, Phinney and scientist Tim Noakes wrote an editorial that stated that in the past 31 years, there have only been a handful of studies measuring sports performance and low carb diets. Out of a total of 11, only 3 found exercise improvements.
Recently a large study was released which contains a collection of 200+ keto and carbohydrate studies. Pretty big deal. Part 1 of the series looked at the ketogenic diet’s impact on body fat, muscle mass, strength and endurance.
what the research says
Studies found greater lean body mass loss in individuals following a ketogenic diet. However, since lean body mass contains water, glycogen and muscle protein, it was hard to determine whether lean body mass in the studies meant a loss in muscle protein or water and glycogen.
Studies found that endurance performance, whether it was anaerobic or aerobic was impaired or maintained with a ketogenic diet. Majority of studies used in this review had small sample sizes, no control group or were very short in duration. Because of this, it is still unclear whether endurance performance is enhanced or impaired with a ketogenic diet.
The majority of the studies found that there was no statistically significant difference between the groups when it came to strength performance. Having said that, researchers had a tough time comparing the diets since protein and total energy were not matched.
To date, no studies have evaluated the long term effects of the keto diet on sports performance. That does not mean that the keto diet won’t be effective. For now we don’t yet have the evidence to draw strong enough conclusions to call it standard best practice.
Weight Loss vs ketogenic diet review
Most people are use this diet for rapid weight loss (surprise, surprise). Let’s take a look at what the literature says.
First of all, I can’t deny the fact that people will lose weight on a keto diet. Here’s why. First of all, you’re eliminating a major food group. When you do that, you limit your food options and most likely your food intake, so it’s not rocket science that you’ll likely lose weight. Second, most people on a low carb diet tend to increase their protein intake in the absence of carbs and there is some evidence that consuming higher amounts of protein may have some weight loss benefits. The large recent study mentioned above also looked at fat loss and found that individuals following a keto diet lost about the same weight as individuals following a different diet when they ate the SAME amount of calories. However, the studies found that individuals on the keto diet tended to lose body weight quicker.
why you lose weight on a keto diet
Here’s why. The reason the keto diet leads to rapid weight loss is due to the loss of water weight. One of the concerns with the keto diet is the loss of muscle mass and the depletion of glycogen stores. Glycogen, which stores our glucose, also stores water, so when stores are depleted, we flush out excess water. In other words, that rapid weight loss isn’t fat, it’s just water.
The keto diet also has an impact on our hormonal levels. Many studies have looked at whether the state of ketosis suppresses our appetite through the actions of leptin and ghrelin. A 2013 study found that after patients lost weight on a keto diet, our hunger hormone (ghrelin) was altered and suppressed. A systematic review also concluded that the state of ketosis appears to be a plausible explanation for the suppression of appetite. So this the keto diet may be good for dieters who can’t stand the discomfort of hunger. Finally, the keto diet also may have an impact on our stress hormone, cortisol. This was demonstrated in a Harvard study where the keto diet resulted in an increase in cortisol in individuals following a very low carb keto diet. High levels of cortisol is associated with insulin resistance, cardiovascular disease and may promote fat accumulation.
So we got the short term effects, but what about long term impacts of the Keto Diet?
So one study looked at the long-term effects of a keto diet in obese patients and after 24 weeks, patients lost weight, reduced their total cholesterol, LDL, triglycerides and increased their HDL. Another study conducted on 132 obese patients found that the low carb (keto) group lost more weight than the low fat group while improving biomarkers like decreased triglycerides, improved insulin sensitivity, and decreased fasting glucose. This all was confirmed in a 2013 meta-analysis, 13 RCTs (1,569 participants) found that patients assigned to a very low carbohydrate diet resulted in greater weight loss compared to those assigned to a low-fat diet.
There are also studies suggesting that long term carbohydrate restriction diets may result in fast short term weight loss. The caveat is that these people gain it all back in the long term. An RCT put 63 individuals on a low-fat diet or a low carb diet, and the study found the low carb dieters lost more weight compared to the low fat group by month 3 and 6, but that the weight loss evened out by month 12. This was confirmed by a Meta-analysis which found that while low-carbers lost more weight than low-fat dieters but the differences disappeared by the one year mark.
diets don’t work
One thing we know about diets and weight loss is that they don’t work. I’ve written about this in depth with regards to the participants on the Biggest Loser. This was evident in a study analyzing 31 long term studies on dieting, which found 2/3 of dieters put back the weight they lost. Other research has reported the failure rate may be as high as 95%. Any diet that is restrictive and unrealistic may be nearly impossible to sustain.
While the keto diet may result in weight loss, what are the dangers of doing this long term?
Potential keto diet danger
Loss of Muscle Mass
A huge concern with the keto diet is the maintenance and potential loss of muscle mass. Many people will just think: hey, dummy, then just eat more protein. Some research has shown that even if your protein intake remains constant, a low carb diet may promote muscle loss.
A study from the Netherlands confirmed these findings. In the study, participants consumed three diets (high carb, moderate carb, low carb) and moderate protein. The study found that those following a low carb diet experienced increased muscle breakdown. This is because when we eat carbohydrates, we produce insulin which promotes muscle growth. This is why athletes depend on carbohydrates (along with protein) to fuel their performance. When we eat carbs, the insulin release “unlocks” our muscles to let the protein in so it can do its job at building our muscles. When we skip carbs all together, muscle glycogen stores get depleted, we lose out on those muscle building opportunities. Forget about high intensity training. A depleted glycogen store also means our workouts will suffer because we just don’t have enough oil left in the tank.
This was a again suggested in the recent review looking at many ketogenic studies. The studies found that there was greater lean body mass loss in the ketogenic groups compared to the other diets being studied.
Keto “Flu” and Bad Breath
Since our body isn’t used to using ketones, we tend to feel flu-like when in ketosis. Lots of brain fog, fatigue, headaches, nausea and poor endurance. You also get bad smelling breath, sweat and pee from the acetone (a byproduct of fat metabolism). Sexy? Not so much. Thankfully, over time, a lot of people report that most of these side effects start to go away.
Constipation is one of the most common onset side effects of following a keto diet. A ten-year study looking at the effects of a keto diet on 48 children found that 65% of the children experienced constipation. A low carb diet means you’re missing out on fibre-rich grains, fruits and certain vegetables.
With the high intake of fat, are we concerned about the high intake of cholesterol? YEP. A study using the keto diet as a form of treatment for epileptic seizures in children found that after 6 months of administering the diet, triglyceride levels increased, total cholesterol levels increased, and HDL and LDL increased. These results suggest that over time, a keto diet may lead to an increased risk of hypercholesterolemia and hypertriglyceridemia. In the same ten-year study, 40% of patients developed hypertriglyceridemia and 29% of patients experienced hypercholesterolemia. So, if heart disease runs in your family, you may want to bow out now.
Strict dietary restriction means we may be missing out on crucial vitamins and minerals. With the keto diet, major minerals that are missed include sodium, potassium and chloride which is why they are typically supplemented with a table salt tablet. Other vitamins that might be missed out on include vitamin D, calcium, magnesium, selenium and zinc. The lack of vitamin D and calcium puts keto dieters at risk for reduced bone health and increased risk for fractures and long term bone diseases.
The Verdict on the Keto Diet
Cutting out a whole food group (or in this case, more than one) is a dietitian’s worse nightmare. First, it makes it a really hard diet to follow. Second, it stresses the hell out of your body and makes it work a lot harder to keep up. In a US News & World Report’s review of 2018 diet, the ketogenic diet came in last place as a sustainable means to weight loss because of its restrictive nature.
the importance of carbohydrates
Carbohydrates make up the life blood of our body’s ability to function. Our body’s need it to run efficiently. Carbs promote muscle growth and endurance in athletes and gives us the energy to get through the day.
We’ve seen the role of a keto diet in neurological diseases and as a form of treatment. The keto diet may also act as a quick fix rapid weight loss tool just like any other restrictive diet. While the risks are likely low if you’re an otherwise healthy individual, I still wouldn’t brush them off as NBD.
More problematic for me is the fact that ANY diet is likely to encourages disordered eating behaviours.
This diet is focuses on how much you can eat and less about the quality of the food you eat. A recent 2018 study found that people who focused on eating plenty of vegetables and whole foods and less on counting calories and limiting food groups, lost a significant amount of weight over the course of a year. This continues to echo the notion that the key to successful weight loss is diet QUALITY and not QUANTITY. And now, there’s research that actually supports that!
I’m a big believer that everything – especially carbs – can be enjoyed in moderation. The best diet is just whatever eating pattern you find most pleasurable that also meets your body’s unique needs. Now I need a summer peach, or a pillowy slice of focaccia, or a mindful bowl of pasta.
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Updated on May 12th, 2020
Abbey Sharp is a Registered Dietitian (RD), regulated by the Ontario College of Dietitians. She is a mom, YouTuber, Blogger, award winning cookbook author, media coach specializing in food and nutrition influencers, and a frequent contributor to national publications like Healthline and on national broadcast TV shows.