The ketogenic diet is famed for being a high fat, very low carb diet. Today it’s mostly used by those wanting to lose weight. The emphasis is on eating fewer carbs to lose weight. But with calories being the leading driver towards weight, that leads to the question; do calories matter on keto?
Yes, they do. On any diet, this principle always holds true. It doesn’t matter if it’s keto, calorie counting, whole 30, low fat, fasting or clean eating. The common denominator between every diet is, they cause you to eat fewer calories than your body burns. In the same way if you spend more than you earn, you go into debt. If you drive faster than the speed limit, you’d still be speeding. These are all laws that can’t be bypassed.
Does that mean Keto is useless? No not at all. Keto has its place, but before you butter your coffee, lets see how it can help your weight loss and how it may make things harder.
What is keto?
There are various variations of the keto diet, however for this I will mainly discuss the standard keto diet and protein keto diet.
Standard ketogenic diet (SKD): This is a very low-carbohydrate with moderate-protein and high-fat diet. It typically contains 70 per cent fat, 20 per cent protein and only 10 per cent carbohydrates.(Mohan & Shilpa, 2018) (1)
High-protein ketogenic diet (HPKD): This diet includes more protein and the ratio around 60 per cent fat, 35 per cent protein and five per cent carbohydrates but as can be seen, it is still a very high fat diet.(Mohan & Shilpa, 2018) (1)
As you can see it’s a very low carbohydrate diet. Carbohydrates are usually kept to under 50g per day and in some cases under 20g a day. The diet emphasises the use of fat for fuel instead.
By going very low carb, what happens is; the body stops using glucose as its main source of fuel. Instead, it uses ketones, hence the name Ketogenic diet.
Is keto effective?
You may be thinking that all sounds well and good, but still, do calories matter on keto?
Historically Keto was found in 1924, as a tool to control epilepsy. However in the last few years, there has been a lot of evidence following a low carb ketogenic diet, has helped people lose weight and even put diabetes into remission. (2)
In fact a lot of studies show, when compared to a low calorie diet, people on keto do tend to lose more compared to those on a low fat diet.
A study done in 2004, showed those on the Keto diet lost on average 9.4kg of fat over 24 weeks. Those on the low-fat diet only lost 4.8kg. The keto group also had more people complete, the study, showing better adherence. (3)
Another study in 2012, compared Keto to a standard low calorie diet. After a year the Keto group lost on average 19.9kg of weight and the low calorie group lost 7kg.
As you can see, Keto definitely works for weight loss. So why would I still claim calories are still the most important element?
What are calories?
Calories are the units of energy we use for fuel. All the food we eat contains calories and the energy we burn is in calories.
The amount of heat needed to raise the temperature of one gram of water one degree celsiusCollins dictionary
Carbohydrates, fats and proteins all contain different amounts of calories, per gram.
|Macronutrient||Calories per gram|
The body burns a certain number of calories per day, depending on lots of factors. You eat a certain number of calories per day.
- If you eat the same, your weight stays the same
- If you eat less, you lose weight
- If you eat more, you gain weight
This is the ONLY way, body weight can be controlled. (4)
My calorie calculator, is a good place to find out how many calories you burn per day.
Why Keto works?
Despite it being calories, that’s causing weight loss, that doesn’t mean Keto is completely useless. There are reasons why Keto is making people eat less calories, easier compared to other diets.
Glycogen water manipulation
When we eat carbohydrates, it gets used as energy in the blood and brain. What doesn’t get used, gets stored as glycogen in the muscle and liver. Then when we are low on carbs, glycogen will get broken down and used as fuel.
Well, when you go on the Keto diet after a day or two. All your glycogen gets used up. You’re not eating carbs, so nothing is getting stored.
Why does this matter? Well for every gram of glycogen in your body, it carries 3 grams of water. The average person stores 600g of glycogen in the body. (5) So when the glycogen is gone, they lose 2.4kg, which is 5.3 lbs.
So before losing any body fat, you’ve already lost 5.3lbs of weight. This is why people on Keto lose a lot of weight fast, it’s not fat, it’s water. As soon as you eat carbs again, you’ll gain that weight back.
But, it does come with a positive. Whether you know if it’s the glycogen or not. Seeing a big drop in weight, cause a massive dose of motivation. When people are motivated, whether for false reasons or not, they are more likely to stick with the diet.
Although classic keto is supposed to be low protein, a lot of people and studies tend to use the high protein keto diet. Why is the significant you may ask?
Well, protein is very beneficial when it comes to weight loss.
- It’s the most satiating macronutrient
- It has the highest thermic effect on food
Compared to fat and carbs, protein has been shown to be the most filling macronutrient. That’s why bodybuilders swear by high protein diets. Lots of modern data is suggesting people eat more protein to control their appetite too. Protein stimulates certain hormones, that help keep us full. (6)
When we eat, our body burns calories to break down our food. When we eat protein, 15-30% of the calories get burnt, during digestion. For carbs, it’s 5-10% and for fat, it’s 0-3%. (7)
|Macronutrient||Percentage of calories burnt during digestion|
A lot of people think, that the diet is magic. But in reality, it’s that the diet, is super simple. Remove a whole food group and you subsequently eat a lot less calories.
There isn’t too much thinking involved. Unlike counting calories, where you have to monitor, weigh and log food into a phone. With a Keto diet, all you need to do is not eat something if it has carbohydrates.
It also cuts out pretty much any, hyper palatable junk food too. You may have noticed pretty much all easy, high calorie, non nutritious food, is a combination of sugar, fat and salt. These foods stimulate the reward centres in our brain, hence why we tend to eat lots of them.
“It is clear by now that in particular palatable hyper calorie foods, like addictive drugs, may produce powerful changes in the brain reward circuitry that we did not evolve for, leading to overconsumption and weight gain”(Morin et al., 2017)
Well, with keto, these foods are all off-limits. Therefore, it’s a lot tougher to overeat.
Stable blood sugar
A lot of people on the Ketogenic diet, say their appetite is next to non existent at times. I’ve done low carb myself and can attest to that feeling.
A 2005 study showed, diabetics on a low carb diet, dropped their calorie intake spontaneously, by nearly 1000 calories per day.
Though insulin isn’t the stable cause of weight loss or weight gain. When insulin is elevated, when blood sugar is high, it’s thought that can increase appetite. Obviously, when you’re not eating carbs, insulin will always remain stable. Therefore you’re not going to get increased hunger cravings. (8)
So, do calories matter on Keto? Yes, they do, but there’s an argument, doing Keto automatically allows you to eat fewer calories, without being as hungry.
Reasons against keto
Yes, we derived for a lot of people, keto helps people eat fewer calories than they burn. But, it doesn’t make it all sunshine and roses.
Before calories, the most important element of a diet is adherence. It doesn’t matter how good a diet is, if you can’t stick with it, it is useless.
There’s one big problem with Keto. Carbs are delicious. If anything, the majority of our favourite meals contain carbs. If yours doesn’t you’re lying to yourself.
If you have a lot of weight to lose, can you really see yourself doing it six months or a year from now? Can you say you’re going to enjoy this? Are you going to be that person who only eats the cheese and tomato, when you go out for pizza? Are you going to skip, cake on your birthday? Are you skipping roast potatoes on Christmas?
Glucose is the bodies preferred fuel source when exercising. Yes the body can use fat for fuel, but that’s for low intensity exercise such as walking. If you want to hit the gym as good as possible, carbs is what your body needs. I know exercise isn’t needed for weight loss, however regular exercise is great for controlling hunger and helping you sustain a healthy diet.
So you can workout adequately, but it won’t be as enjoyable as it would be if you had some carbs in your system.
May raise blood cholesterol
This isn’t true for all low carb diets. But if you are eating mountains of cheese, putting butter and cream in your coffee and eating lots of meat fat, you be assured, your risk of getting high cholesterol will increase. Saturated fat from animal sources, is linked to high cholesterol. (9) This is not to say these foods should never be eaten, but when a diet is high in fat, it’s likely these foods will be consumed, as they are somewhat pleasurable.
Make sure the majority of your fat comes from unsaturated fats. Your nuts, olive oil, vegetable oils, avocados and nut butter etc. Not only do these foods not increase your risk of high cholesterol, but they also raise your food cholesterol which does wonders for your heart. (10)
No difference in fat loss
This is the kicker. Every study has shown, when a low carb diet and a low fat diet are matched for calories and protein, fat loss is exactly the same. The studies where Keto is better, the calories and protein are not controlled. But when they are fat loss is the same. This shows, it really is calories that matters.
A six-month study in 2004, showed that when calories and protein were matched fat loss was exactly the same. Health markers such as blood lipids and cholesterol also improved in both groups at the same rate. The only difference being the low carb had more food cravings. (11)
Do calories matter on keto? They sure do. You might hear, that you don’t have to count calories on Keto. That is 100% true. But just because you don’t have to count calories, doesn’t mean calories don’t count.
Keto has its place. If you want quick drops in the scale, to get some initial motivation it works great. If you want a diet, that requires little thinking, cuts out most of the foods, that make us gain weight and want to stabilise your appetite, keto may help.
If you like bread and want to push yourself in the gym, you like 99% of the world, may want to reconsider before you go keto.
I’m not saying Keto is good or bad, I’m saying, calories will always matter the most. if Keto means you can eat fewer calories great, but if you like pizza, pasta and cake, think again.
Josh is a Registered Associate Nutritionist, with the Association for Nutrition (AFN). He completed his degree in Nutrition at the University of Roehampton in 2021. He passed with a First Class with Honours.
Josh is also a tutor for up-and-coming Personal Trainers, where he teaches a Level 4 Advanced Nutrition course. This is for Personal Trainers looking to upskill their nutrition knowledge. This is done at Norfolk Health & Fitness.