Updated: Oct 14
So you're contemplating jumping onboard the 'Ketogenic' diet?
Before we proceed any further, one must always remember:
Any Diet works so long as you are in a Caloric Deficit!
🏼The ketogenic diet will severely restrict your carbohydrate intake.🏼
How restricted are we talking? To quickly highlight a few restrictions of the 'Ketogenic' diet, this will usually mean no more traditional: 🚫 Beer 🚫 Pizza 🚫 Cake
🚫 Cupcakes 🚫 Ice Cream
🚫 Jelly 🚫 Fruit
🚫 Juice 🚫 Candy 🚫 Pasta 🚫 Oatmeal 🚫 Rice 🚫 Bread
🚫 French Fries
🚫 Cereal etc. Basically to be in Keto, you will want Carbohydrates to be very very minimal!
Any significant quantity of carbohydrate/sugar that can be converted to glucose/glycogen in the system is a no.
So if you DO NOT particularly enjoy high fat foods (cream, cheese, eggs, avocado, nuts and seeds etc.), but you love sweet, high carb foods, a ketogenic diet is NOT going to yield positive results.
Furthermore you will need to sustain this dietary lifestyle for good or you may run the risk of time wasting, losing money whilst increasing the likelihood of binge eating!
Now that we've covered some of the cliff notes on Keto, lets explore some of the biochemical adaptations that take place and how to truly become keto-adapted!
WHAT IS KETO?
The ketogenic (keto) diet represents possibly the most extreme application of carbohydrate restriction. To put it simply you are using dietary fat (ketones) as an alternate fuel source as opposed to carbohydrates (glucose/glycogen).
As a simple rule of thumb, keto dieters will most often consume 70-80% of calories from fat, while restricting protein (15-25%) and carbohydrate (<5-10%) intake.
The premise of the diet is that restriction of carbohydrate (and, to some degree, protein) increases reliance on fat for energy, and increases the production and utilization of ketones as a fuel source...
Roughly 50g - 100g of glucose is required to prevent you being in ketosis (high levels of ketones in the body) . To be in true 'Ketosis' you'll need to be consuming sub -50g Carbohydrates per day...
If protein or carbohydrate intake are too high, you’ll likely maintain some reliance on carbohydrate, and ketones will not be produced in sufficient quantities.
From a biochemical perspective, the body adapts by enhancing its ability to derive energy from fat and ketones, whilst its reliance on carbohydrate for energy is reduced.
All elicited extreme viewpoints aside, what is keto actually good for?
Well, some really cool things happen when these biochemical adaptations take place and you become keto-adapted.
There is evidence of some seizure disorders that are caused by faulty carbohydrate metabolism in the brain. When these patients go keto, their brains learn to use ketones instead of carbs for energy, and the frequency and severity of their seizures are dramatically reduced .
In fact, the brain essentially becomes immune to hypoglycemia (low blood sugar) — even at blood glucose levels that would typically put someone into a coma, individuals who are keto-adapted from prolonged fasting are totally fine .
When it comes to body composition, there are some nice benefits as well. Most notably, ketogenic diets seem to reliably reduce appetite  due to the high dietary fat satiety factor.
^From a practical standpoint, it’s also very easy to avoid grazing or snacking when you’re on keto because of this.
An intriguing component of keto is its potential effects on exercise performance...
For most Endurance athletes running out of stored carbohydrate (glycogen/glucose) is one of the primary performance killers they face.
For strength and physique athletes, issues arise even before even running out of fuel as evidence has shown that glycogen depletion happens in a non-uniform manner, with preferential depletion occurring near the sarcoplasmic reticulum .
This is problematic, as the sarcoplasmic reticulum is a huge regulator of the muscle’s ability to create force. So if you're a strength athlete, performance in the gym will generally tank and get worse first before getting any better!
IF we adapt to a keto diet, the adjustment period to keto and performance generally takes weeks...but once we've adapted, you will undoubtedly use more fat (ketones) for energy, and less carbohydrate .
PROTEIN AND KETO
Ok, so before we proceed to settle into a cushy keto diet, there is still one remaining macronutrient factor, protein.
For individuals whom sincerely LOVE protein, they will quickly find difficulty adhering to the 15-25% restriction on Keto. One of the reasons why the Keto breakdown involves 70-80% of calories from fat, 15-25% from Protein and 5-10% from carbohydrate is to mitigate the excess of protein amino acids.
Although not a significant source of energy for most activities, protein can be broken down into its constituent amino acids by various metabolic processes. Any sudden onset of excessive amino acids must either be converted into other storage products or oxidized as a fuel source.
Therefore, in theory, the excess ingested protein could, through the process of gluconeogenesis, produce glucose.
The process of converting glucose to glycogen is called 'glycogenesis'. The liver has the highest glycogen content of all the tissues in the body and, in fact, can convert many of the end products of digestion (i.e. noncarbohydrate sources) into glycogen—a process called 'gluconeogenesis'.
This would mean that 100 g of extra protein could produce +/-50 g of glucose kicking you out of Ketosis!
What the studies show is that high protein diets cause more fat loss compared to normal or low protein diets when calories are equal between the diets . Furthermore, a high protein diet has been shown to be superior to normal/low protein diets in maintaining muscle mass and improving body composition during a diet.
These studies also showed that normal/low protein diets caused muscle loss during a calorie deficit while a high protein diet effectively maintained muscle mass and improved body composition!
Thus, if your diet has a substantial amount of energy coming from protein. The benefits in fat and ketone utilization will come at a cost if not accounted for.
CARBOHYDRATES VS KETO
Ok, so by now we should have a relatively good idea of some of the nutritional adjustments that need to be made to successfully be in Ketosis.
But what if we compare it to a balanced or plant based diet?
According to a 2007 study from Arizona state university, 2 groups of dieters were placed on the same iso-caloric diet equating protein and calories. However one diet group followed 'Keto' whilst the other diet group applied a moderate carbohydrate / fat model.
The study demonstrated the 'thermogenic' benefits of the Keto diet due to the higher protein intake as opposed to the standard higher fat intake of a keto diet.
Both groups in the end lost the same amount weight and bf%. However whilst Health markers were very similar in both groups, there were several noted adverse metabolic and emotional effects from the keto focused group.
This aligned with further past research conducted by Dr Kevin Hall (also funded by NuSi - a pro Keto group) demonstrated that fat loss was the same between a keto and non-keto diet when calories were controlled.
Note: for the record, ^this was also a metabolic ward study which is highly tightly controlled with every calorie fed meal being provided for by the university and accounted for.
Another recent review comparing low fat:high carb (plant based🌿) vs keto (animal based🥩) found almost equal outcomes on appetite suppression and weight loss.
Whilst the plant based high glycemic containing diet experienced significant increases in glucose & insulin levels. They also experienced decreased levels of spontaneous energy (calorie) intake contradicting the outcome predictions.
The results of the study further contrasted the carbohydrate insulin model of obesity where high carbohydrate diets increase hunger alongside elevated insulin, whereas this study does not support.
Fat oxidation aka 'burning' vs Fat loss?
High Dietary Fat vs High Carbohydrate diets are often compared in an effort to distinguish which is beneficially superior for weight management.
When compared, there's evidence of a high fat diet allowing you to oxidize more fat vs a high carbohydrate diet causing less fat oxidation when they are used as fuel.
Whilst higher dietary fat consumption causes more fat oxidation vs high carbohydrate, this also does not necessarily result in fat loss. High dietary fat diets will oxidize more fat but also store more bodyfat.
A high carbohydrate diet whilst causing less fat oxidation will also result in less bodyfat storage (1-2% approx) when compared to a high dietary fat diet.
Fat loss and Fat oxidation aren't always mutually exclusive.
It is the overall energy (calorie) balance that is the overall determinant whether or not we will successfully lose, maintain or gain bodyfat.
Lastly, a recent meta-analysis also demonstrated of the summation of most studies showing no difference in energy expenditure or fat loss between low fat vs low carb diets.
However, one interesting finding was where restricting fat produced slightly more fat loss when everything else was equal (~16g more per day body fat loss).
🏼So, if you've made it this far and the science has you convinced otherwise, proceed no further than here...if this is more of a lifestyle change than just looking to drop bf%, lets proceed...🏼
APPLYING THE KETOGENIC DIET
^As per the aforementioned effects of protein and ketosis, we need to be comfortable with permanently restricting protein to a 15-25% ratio before proceeding...
We also know we need to consume 70-80% of calories from fat, 15-25% from protein and the remaining <5-10% from carbohydrates...
We can now calculate what our calorie and macro ratio needs to be for true ketosis.
Note: there are various calorie calculators available online. I have also included a simple version in my Eating for a Purpose eBook.
Using the below caloric example:
2000 kcal / 70% - 80% = 1400 - 1600 kcal (155g - 177g F)
2000 kcal / 15% - 25% = 300 - 500 kcal (75g - 125g P)
2000 kcal / 5% - 10% = 100 - 200 kcal (25g - 50g C)
Note: above Daily Calorie requirements based off of 60kg individual.* Always consult a Dietitian or Nutritionist before embarking on dietary changes.
Keto is fast becoming the polarizing diet subject in the world of health and nutrition. However, what works for one single individual can also be a disaster for another.
Can we achieve Fat loss with Keto? Yes we can.
Can we build muscle on Keto? Probably.
Can we improve our Health biomarkers on Keto? Sure.
Can we get the same result eating carbohydrates? Absolutely.
Whilst those with health concerns are normally advised to follow specific diets, this does not mean the general populace need to also...
If you're ok with some potential LBM (Lean Body Mass) loss and lower protein intake, than Keto may very well work for you...
In truth all popular dieting tools have the premise of offering you the same result. However:
A successful diet is one you can stick to long term!
Make the right choice for YOU.
1,2,3 NSCA – Essentials of Strength Training and Conditioning 3rd Edition. Glycogen, Bioenergetics of Exercise and Training, p33 & p190. Carbohydrate requirements p211. Gluconeogenesis p209.
4. Layman DK, Evans E, Baum JI, Seyler J, Erickson DJ, Boileau RA. Dietary protein and exercise have additive effects on body composition during weight loss in adult women. J Nutr. 2005 Aug;135(8):1903-10.
5, 8. Feinman RD, Fine EJ. Thermodynamics and metabolic advantage of weight loss diets. Metab Syn Relat Dis. 2003. 1:209-219.
6. Brehm BJ, Seeley RJ, Daniels SR, D'Alessio DA. A randomized trial comparing a very low carbohydrate diet and a calorie-restricted low fat diet on body weight and cardiovascular risk factors in healthy women. J Clin Endocrinol Metab. 2003 Apr;88(4):1617-23. https://www.ncbi.nlm.nih.gov/pubmed/12679447
7. Layman DK, Evans E, Baum JI, Seyler J, Erickson DJ, Boileau RA. Dietary protein and exercise have additive effects on body composition during weight loss in adult women. J Nutr. 2005 Aug;135(8):1903-10.
8. Effects of Adherence to a Higher Protein Diet on Weight Loss, Markers of Health, and Functional Capacity in Older Women Participating in a Resistance-Based Exercise Program. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6115985/
9. The American Journal of Clinical Nutrition, Volume 83, Issue 5, 1 May 2006, Pages 1055–1061, https://doi.org/10.1093/ajcn/83.5.1055
10. Effects of a low carbohydrate diet on energy expenditure during weight loss maintenance: randomized trial.
11. Obesity Energetics: Body Weight Regulation and the Effects of Diet Composition
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5568065/ 12. Increasing dietary fat elicits similar changes in fat oxidation and markers of muscle oxidative capacity in lean and obese humans.
13. Obesity Energetics: Body Weight Regulation and the Effects of Diet Composition.https://www.ncbi.nlm.nih.gov/pubmed/28193517
14. Calorie for calorie, dietary fat restriction results in more body fat loss than carbohydrate restriction in people with obesity