Considering the ketogenic diet? Read and think again

Considering the ketogenic diet? Read and think again

You probably know someone on the “Keto” diet or are tempted by the claims that this special diet helped many people lose weight in just 10 days.

What is this magic diet that everyone talks about? Does it really work? Is it safe?

What is the ketogenic diet?

The keto diet is a low-carb, high-fat plan that promises quick weight loss.

In essence, it causes the body to release ketones into the bloodstream after the body is starved of its preferred energy source – glucose from carbohydrate. This metabolic process is known as ketosis.

Instead of consuming carbohydrates such as grains, this diet typically involves plenty of meat and dairy.

ketogenic diet bacon

This shift from using glucose to breaking down fat as a source of energy could happen after two to four days of consuming fewer than 20-50g of carbohydrates per day.

Roughly speaking, 70-80% of the calories on a keto diet come from fat, 20% from protein, and as little as 5% from carbs.

Because of the heavy restrictions, it is extremely difficult to stick to, as just one potato or slice of bread could exceed an entire day’s carbohydrate allowance.

But putting the practical difficulty aside, the potential dangers are what people should really be aware and concerned about.

Insulin resistance

Free fatty acids result in inflammation, toxic fat breakdown products, and oxidative stress, which are highly detrimental to the essential insulin receptor pathway.

What does it mean? Being on a long-term keto diet puts you at risk for insulin resistance.

ketogenic diet diabetes

See Dr. Micheal Gregor’s article “How a Low-Carb Diet is Metabolically Like Being Obese“.

You might know that insulin resistance is what causes type 2 diabetes, and the consequences of type 2 diabetes are debilitating. If you are not familiar with the topic, watch this video What Causes Insulin Resistance?

In short, as the level of fat rises in your blood, the body’s ability to clear sugar drops. Just hours after eating fatty foods, the amount of fat detected in the blood increases, and insulin sensitivity decreases.

Studies have shown that fat directly inhibits glucose transport and utilization in our muscles, preventing 85% of the glucose being cleared out of the bloodstream.

For someone who is already pre-diabetic or diabetic, the keto diet is extremely dangerous. 

Ketosis can trigger a dangerous condition called ketoacidosis. This is when the body stores up too many ketones, and the blood becomes too acidic, leading to damages to the liver, kidneys, and brain. Ketoacidosis can be fatal if left untreated.

This randomized control trial highlights the importance of wholegrain intake for overweight and type-2 diabetics.

The Keto flu

Many people report feeling sick and weak when switching to a keto diet, a phenomenon known as the “Keto flu“. It can involve nausea, stomachache, cramps, and constipation.

Worst of all, many keto dieters report bad breath, which comes from acetone, a product of ketone metabolism.

ketogenic diet bad breath

Diarrhea is also common on a keto diet, due to a lack of fiber when you remove whole-grain foods such as bread and pasta, as well as vegetables. It can also result from an intolerance to dairy or artificial sweeteners contained in processed foods.

Increased all-cause mortality

A systematic review and meta-analysis of low-carb diet studies reached the conclusion that low-carbohydrate diets are associated with a significantly higher risk of all-cause mortality.

But…surely the keto diet contains more proteins, and wouldn’t that be a good thing?

No. Animal proteins have also been linked to higher mortality.

A study examined the associations of animal and plant protein intake with risk of mortality. This is a huge study consisting of 85,013 women and 46,329 men, tracked over three decades.

The study concluded: “Higher animal protein intake was positively, whereas plant protein was inverse, associated with mortality, especially among individuals with at least one lifestyle risk factors. Substitution of plant protein for animal protein, especially from processed red meat, was associated with lower mortality, suggesting the importance of protein source.

The China Study is another one that revealed increased coronary artery disease mortality rates with animal protein and salt intake, whereas vegetables, plant protein, and legumes are linked with lower mortality rate.

Heart diseases

Low carb diets such as the ketogenic diet affect arteries directly. A review of the best studies on this topic found that low-carb diets impair arterial function, and effectively stiffen people’s arteries.

A new study also reports the same thing: “A dietary pattern characterized by high protein and fat, but low carbohydrate was associated with poorer peripheral small artery function”.

Shockingly, patients with heart diseases who were given a healthy vegetarian diet but later jumped ship to low-carb diets had significantly worsened heart condition, with 40-50% more artery clogging. In the same study, others who continued with the vegetarian diet instead showed a reversal of their heart disease – partially clogged arteries cleared up, with 20% less atherosclerotic plaque!

ketogenic diet heart disease

Read more here “Low Carb Diets Found to Feed Heart Disease“.

Muscle loss and weight regain

You’ll lose weight in the short term of converting to a keto diet, but most of it will be water and muscle loss. This is simply because fat is the last to go during weight loss, any short-term, rapid weight loss most likely has nothing to do with fat loss.

This also means that when you come off the ketogenic diet, you are likely to regain the original weight. And instead of regaining lean muscle, you’re likely to regain fat. The diet may cause lasting effects on your resting metabolic rate, and your long-term weight management.

ketogenic diet muscle loss

Poor athletic performance

More than skeletal muscles, the diet can potentially damage the heart, which is also a muscle. What’s more, high-fat intake unquestionably raises cholesterol levels, a known risk factor for heart diseases.

Because of the excessive acidic ketone production, the body is in a more acidic state, which is known to impair muscle performance and contributes to fatigue.

recent study in the Journal of Sports Medicine and Physical Fitness also reported worse performance of cyclists and runners just after four days on a ketogenic diet. This could be the combined result of an unhealthy acidic environment for muscles, heart and various other organs.


The ketogenic diet may give you rapid weight loss, but what you lose is mostly just water and muscle, which is neither healthy nor sustainable.

Long-term adoption of the ketogenic diet raises the risk for many diseases and mortality risk, doing more harm than good.

Other than health, the over-consumption of meat and dairy also means that this diet is the exact opposite of environmental sustainability.

We encourage you to eat a variety of plant-based foods, including plenty of carbohydrates!

vegan health

Want more information on the keto diet?

Keto Diet: Myths and Facts

9 Nutrition Studies Every Ketogenic Dieter NEEDS To Read

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Have you checked out our comprehensive Vegan Health & Nutrition Resources page? We have a bunch of support materials waiting for you including a dietitian guidebook, lifestyle checklists and assessments, and the best vegan websites we recommend, all for you for FREE.


About the author
healthy vegan palette writer Rainie

Rainie is a health, fitness and nutrition enthusiastic. She studied a bachelor of Biomedical Sciences degree to learn all about the human body and continued to pursue higher research training in a neuroscience laboratory to investigate how the brain develops. Rainie is now using the research skills she learned in the science degree to bring evidence-based nutrition practice to more health-conscious people.