Are the dangers of low carb diets unfounded propaganda or genuine health risks?
In this article we examine ketogenic diets and their impact on cholesterol levels.
The “keto diets are bad for cholesterol” argument has raged on for years and caused a lot of controversy (mainly due to the Atkins diet), but do they really raise cholesterol or is it a myth that refuses to die?
We look at the scientific studies on keto diets and cholesterol levels to establish if this is one of the dangers of low carb diets that’s true.
It’s generally accepted that high fat diets raise cholesterol levels which increases the risk of heart problems.
As the keto diet is a high fat diet the general assumption is that it will cause high cholesterol. On the face of it this sounds reasonable but a keto diet is different to the high fat diet of your “Regular Joe” (e.g. fries, pizza, etc) so we need to look to science to provide the answers.
Need some help understanding cholesterol?
Scientific studies are the best place to draw our conclusions; however, the scientists themselves are not always consistent in their methods. This is why you will often studies that contradict each other
Pro-keto gurus will spin the studies in their favour and keto detractors will always cite this as one of the dangers of low carb diets. I simply intend to refer you to the key studies and try to help you decide for yourself.
The Original Keto Studies
When keto diets were first studied, they did in fact report an increase in cholesterol. This is probably where the “keto raises cholesterol” mantra originated.
In this study, one of the original studies (1981) that monitored the impact of a ketogenic diet on cholesterol levels. It is often cited as proof of the increase in cholesterol associated with keto diets.
The effect of a high energy, low carbohydrate (ketogenic) diet on serum levels of lipids and lipoproteins was studied in two normal individuals.
- There was a marked rise of total cholesterol
- HDL Cholesterol (good cholesterol) levels remained the same
- LDL Cholesterol (bad cholesterol) levels returned to normal once the diet ended
The second study which is regularly referenced is this one from 1974 which looked at the change in cholesterol levels during a diet called the Stillman diet which is similar to a keto diet it is protein and fat dominant.
The cholesterol levels of 12 healthy volunteers were monitored which they followed the diet. They followed the diet for between 3 and 17 days (average of 7.6 days)
- Total cholesterol levels increased in every case
- The high levels of cholesterol in the blood (hypercholesterolemia) presents potential risks, particularly in people with existing heart problems
The Newer Keto Studies
Based on the original studies it would be a fair assumption that ketogenic diets increase cholesterol and that this validates cholesterol as one of the dangers of low carb diets.
However, this notion was challenged by a number of later studies which contradicted the findings of the original studies.
In this study from 2004, scientists compared a low fat, low cholesterol diet with a standard ketogenic diet.
120 overweight individuals who already had high cholesterol levels (hyperlipidemia) were monitored.
One group followed a low carbohydrate diet (less than 20g daily) plus supplementation and exercise whilst the second group followed a low fat diet (less than 30% fat) whilst in a calorie deficit plus exercise.
The scientists measured body weight, body composition, cholesterol levels and tolerability.
- A greater proportion of the low carb diet group completed the study (76%) compared to only 57% of the low fat group
- After 24 weeks weight loss was greater in the low carb group
- The low carb groups total cholesterol levels decreased more than the low fat group
- The low carb groups HDL cholesterol (good cholesterol) levels increased more than the low fat group
- LDL cholesterol (bad cholesterol)levels did not increase in either group
This demonstrates that during active weight loss, the ketogenic diet showed a greater decrease of total cholesterol levels and a greater increase in HDL levels compared to the low fat diet.
A second study from 2006 looked at the long term effects of ketogenic diets in obese individuals with high cholesterol.
In this study, the 66 people selected to participate had high cholesterol levels. They were put on a keto diet and monitored over 56 weeks.
- The body weight and body mass index of both groups decreased significantly.
- The level of total cholesterol, LDL cholesterol, triglycerides and blood glucose decreased significantly in both groups.
- HDL Cholesterol increased significantly in both groups after the diet ended
A possible reason for the conflicting results is that the newer studies used obese individuals and as weight loss itself can reduce cholesterol levels, it’s hard to know whether the diet or the weight loss caused the change.
In reality, the majority of people interested in ketogenic diets are interested in losing weight so it could be argued that cholesterol levels will fall regardless.
However, I know a number of people will still be sceptical since there are no absolute conclusions that can be drawn on the dangers of low carb diets based on the studies conducted to date.
That said, there are millions of dieters around the world who follow this type of diet and experience no ill effects (I am one myself) so it all comes down to your personal preferences.
Ketogenic diets are an effective way to lose weight so there is an obvious appeal despite the potential side affects. If you’re still unsure about the dangers of low carb diets such as keto, then these tips will help to ensure you minimise any risks:
- Use ketogenic diets temporarily – When you want to lose fat and retain muscle use keto and then go back to a more “balanced” diet afterwards. This helps reduce the potential dangers of low carb diets like keto.
- Better Fat Sources – Half the fun of keto is the food choices, hamburgers and bacon taste great but they’re processed which is never as good as natural foods. Nuts, avocados, fish and animal fats are all natural and are far better choices.
- Cholesterol Level Checks – If you are genuinely concerned about the dangers of low carb diets despite reading this article you can always check your cholesterol levels. You can have your blood lipid levels monitored before and during the diet. If there are any negative results improve the fat sources (above) first, if this doesn’t improve things then end the diet immediately.