First, restrictive ketogenic diet is not something you should haphazardly go and try without medical supervision. There is not enough scientific evidence on ketogenic diets and their long term effect on the body.
Originally designed as a medical intervention for serious epilepsy by Dr. Russell Wilder, the ketogenic diet has become the current favorite fat loss tool for a lot of celebrities and a-listers. Maybe it’s the answer to all our fat loss problems. Or maybe it’s just another cycle of the low-carb diet trend. After all, Dr. Atkins’ Diet Revolution low-carb diet book came out in 1972.
What is this ultra low-carbohydrate ketogenic diet all about and is it going to stick around? Or is it going to blow over in a year or two followed by another trend?
What is a ketogenic diet
The ketogenic, or keto diet, involves eating majority of the daily calories from fat sources. All the while keeping protein low to moderate and restricting carbohydrates to a minimum.
Carbohydrates are the body’s preferable source of fuel. And since keto diet doesn’t provide enough carbs to sustain the typical energy levels, the body is forced to become more efficient at turning the fat into energy. In ketogenic diet the liver metabolises the dietary fat into ketone bodies which can be used for the energy for brain and the body.
And if calories are kept at below maintenance while simultaneously restricting carbohydrate intake, ketones can be produced as the body is forced to convert stored fat sources into ketones for energy.
You fall into ketogenic diet category when your total daily carbohydrate intake is below 50 grams.(1) But some people need to drop the daily carbohydrate below 20 grams to get into ketosis. In these ultra-low cases the can be exceeded after eating a one granny smith apple.
A typical list of foods that’s included in ketogenic diet includes:
Non-starchy, above-ground vegetables, e.g. broccoli, brussel sprouts, spinach
Fruits low in carbohydrates, e.g. avocado, berries, lemon, lime
Fats, nuts, seeds, oils and high fat dairy. Some dairy can kick the body out of ketosis when the carbohydrate content is too high.
Low calorie sweeteners, e.g. stevia
Low carbohydrate drinks e.g. black tea and coffee
Ketogenic diet upsides
There is evidence on the benefits of ketogenic diet reducing seizures in children with epilepsy, and the benefits of ketogenic diet on brain tumors.
There are also individual accounts on the benefits in modifying Alzheimer’s disease, Parkinsonism, amyotrophic lateral sclerosis, and possibly post-traumatic brain injury, stroke, and severe hyperactivity.(2) That being said, there are no controlled studies of these conditions reported.
Blood sugar control
In a study comparing low carb ketogenic diet, and a high carb low glycemic diets, the ketogenic diet lead to better improvements in blood sugar control in participants with type 2 diabetes.(3) With this study it’s worth noting that the funding was provided the Robert C. Atkins Foundation.
Ketogenic diet downsides
The main downside is that there is not enough long-term studies to determine the true effects of ketogenic diets. As far as the current research goes, we don’t know enough, yet.
Possibly limits the fibre intake
The ketogenic diet can restrict fibre intake, mainly resistant starch which can improve bowel health and good bacteria. Resistant starch is found in cooked and cooled rice and potatoes and under ripe bananas. All of which are relatively dense in carbohydrates and therefore off-limits when trying to keep the body in ketosis.
It is also possible that limiting most fruit, below-ground vegetables, grains, legumes and pulses intake can lead to constipation.
That being said, there is soluble fibre in above ground vegetables (broccoli, brussel sprouts etc) and avocado. And insoluble fibre can be found in nuts and seeds. These foods can be included in ketogenic diet.
Restrictive and can be challenging to maintain
Ketogenic diet often requires frequent measurements of urine or blood samples to confirm that the body is indeed in ketosis.(4) That, no matter how effective the diet would prove to be, is challenging to maintain for the majority of people.
However, some people thrive on extremely low carbohydrate diets and find it easier to stick with compared to other diet approaches. As with all of the most effective diet approaches it comes down to personal preferences.
Is ketogenic diet more effective for fat loss than other diets?
When comparing ketogenic, low carbohydrate and high carbohydrate diets for fat loss, while keeping the total calories the same across all the diets, there was no significant difference between different approaches.(5)
There is also research stating:“Body fat loss slowed during the KD [ketogenic diet] and coincided with increased protein utilization and loss of fat-free mass.”(6) Meaning that more non-fat weight was lost during the ketogenic diet compared to a high-carbohydrate baseline diet.
So, based on the current research, the ketogenic diet doesn’t seem to be more effective for fat loss when compared to moderate and higher carbohydrate diets.
The final takeaway on ketogenic diets
For the healthy population after fat loss it comes down to eating less calories than your body uses.(7) Whether it’s a low-carbohydrate approach or not.
But although ketogenic diet may not be the “super-solution” for fat loss based on current research, it’s not all negative. Some of the research on ketogenic diets is promising. And we will know more about it and its effects on long-term health as more research emerges.
There will always be people who swear by a certain diet approach. And low-carbohydrate vs high-carbohydrate groups are almost evangelical on their conflicting approaches.
When the diet is based around wholefoods, some people get great results on restrictive carbohydrate diet. Others do just as well on a wholefood high carbohydrate plan. And in both groups there are always outliers who don’t fit into the statistical averages we see in research.
I’ll repeat what I said in the beginning of this post. Restrictive ketogenic diet is not something you should haphazardly go and try without medical supervision. There is not enough scientific evidence on ketogenic diets and their long term effect on the body.
(2) Freeman, John, M (2013) Epilepsy’s Big Fat Answer
(3) Westman et al (2008) The effect of a low-carbohydrate, ketogenic diet versus a low-glycemic index diet on glycemic control in type 2 diabetes mellitus
(4) Payne, N.E., et.al. (2011) The ketogenic and related diets in adolescents and adults–a review.
(5) Hall, Kevin, D., et.al. (2015) Calorie for Calorie, Dietary Fat Restriction Results in More Body Fat Loss than Carbohydrate Restriction in People with Obesity
(6) Hall, Kevin, D., et.al. (2016) Energy expenditure and body composition changes after an isocaloric ketogenic diet in overweight and obese men.