Should you count calories on a low-carb or keto diet?
- What are calories?
- How many calories do carbs, protein, and fat provide?
- Calories count, but they are not the whole story
- Counting calories: yes or no?
What are calories?
A calorie is a unit of energy that your body uses to perform hundreds of tasks. These include voluntary movements like walking, running, and jumping, as well as involuntary ones like breathing, circulating blood throughout your system, and maintaining normal body temperature.
Your body needs a certain number of calories just to keep these involuntary processes going. This is referred to as your basal metabolic rate, or BMR. Your BMR is influenced by many factors, including your age, gender, body composition, and genetics.
You require additional calories for physical activity, including walking. Overall, the more active you are, the more calories you’ll need.
How many calories do carbs, protein, and fat provide?
Each macronutrient provides a specific amount of calories:
- Carbs: 4 calories per gram
- Protein: 4 calories per gram
- Fat: 9 calories per gram
Protein is generally considered the most satiating macronutrient, but it’s mostly used for cell repair, maintenance and growth. Thus protein intake is mostly important in order to fill your body’s protein needs. Protein is not very effective as a fuel (i.e. as calories). Excess protein has to first be converted to glucose in the liver, in order to be used as fuel. Eating protein in excess of your body’s needs is not necessarily a good thing, and it can reduce the effect of a strict low-carb diet. Learn more
Pure fats and oils get 100% of their calories from fat. However, the calories in most foods are a combination of carbs, protein, and fat.
For instance, although eggs are considered a protein food, the majority of their calories actually come from fat. For example, two large eggs provide 146 calories:
- 4 calories from carbs (1 gram) (2%)
- 52 calories from protein (13 grams) (34%)
- 90 calories from fat (10 grams) (64%)
Calories count, but they are not the whole story
Generally speaking, if you take in more calories than your body needs over a longer time period, the extra calories will be stored as fat.1 Similarly, if you take in fewer calories than needed over a longer time period, your body will release its fat stores, and you will lose weight.
However, there is far more to weight regulation than just monitoring calories in vs. calories out. Indeed, most members of the human race appears to have regulated their weight effectively for millennia, before anyone even knew what a calorie was.
The modern obesity epidemic appears to be an unprecedented phenomenon, and it coincides with an ever-increased focus on counting calories. Correlation is not causation, so it would obviously be wrong to say that obesity is caused by counting calories. However, counting calories appears to be, at best, an imperfect aid to weight control. So what is really going on?
Hormones play a large role in influencing appetite, fullness, and fat storage. And research suggests that low-carb and keto meals may trigger hormones that lead to a natural reduction in calorie intake, especially in those who are overweight or insulin resistant.2
In one study, overweight people consumed a breakfast of eggs or a bagel. Although each meal contained an identical amount of calories, the group that consumed the egg breakfast stayed full longer and ate fewer calories at lunch than the bagel group did.3
Additionally, your insulin level – and how sensitive your body is to insulin – influence whether you store or burn calories. Researchers have shown that impaired insulin response following weight loss reduces metabolic rate and drives weight regain. However, lowering carb intake may help to counteract this effect.4 What’s more, when it comes to weight loss, low-carb diets regularly outperform low-calorie diets, even in studies where the low-carb dieters are not counting their calories.5
In a 2004 study, overweight and obese adults consumed a low-fat diet and a low-carb diet for one week each. Both diets were designed to reduce each person’s calorie intake by 500 calories per day. However, people lost more weight and body fat after the low-carb week than the low-fat week – even though the men averaged higher calorie intake during the low-carb phase.6
Clearly, calories are only one factor involved in weight regulation.
Video: Doctors answer
Dr. Naiman: Yes, weight loss is all about… No, weigh loss is definitely not about calories. And I have a zillion patients who’ve gone on low calorie diets. And you can lose weight that way and you will immediately regain it. And we have plenty of studies that document this. So weight loss is not all about calories.
Dr. Eenfeldt: Isn’t weight loss all about calories?
Dr. Brukner: Well, so they’ve tried to convince us for the last 30 years. But calories in, calories out has been the philosophy of the 30 years. But, you know, you’re going to tell me that 100 cal from a piece of salmon is exactly the same as 100 cal from candy, or chocolate, or ice cream…
I mean that doesn’t make any sense at all, does it? So I mean calories in, calories out has been disproved. I mean there are calories from differences that have markedly different effects. And until we get rid of this whole calories in…
It’s been a disaster this calories in, calories out. I mean look at the effect. Since we have adopted that philosophy we have worldwide epidemics of obesity, diabetes, faKy liver and so on… It’s been a disaster and the sooner we forget about it… It’s sort of an attractive concept, you know, what you bring in, what you take out… But unfortunately it doesn’t work.
Dr. Eenfeldt: Isn’t weight loss all about calories?
Dr. Westman: Well, I think calories matter. The energy balance equation where we talk about energy in… calories in, calories out isn’t a good construct to help guide people… It’s more complicated than counting the calories on a label, for example.
Because the calories are handled differently depending on what type of calorie it is, based on the metabolism for that individual calorie. But I think that it’s pretty clear that when people are losing weight, they are eating fewer calories than they were before.
And then of course if the weight loss program that they are doing changes the metabolic rate, that’s another factor you have to take into account. But I think it’s fair to say that a low-carbohydrate diet isn’t magical. It follows the rules of science that we understand, having to do with energy balance and the calories.
So when I teach the low-carb diet, I don’t talk about calories. We don’t have to teach calories, but people are still eating fewer calories in general. That’s, you know, not the case for everyone. That’s the role for the practitioner to help people troubleshoot those situations.
Counting calories: yes or no?
At Diet Doctor, we don’t recommend counting calories. First of all, it’s impossible to know exactly how many calories you’re getting from a specific food, let alone precisely what your body will do with those calories. It’s far more important to choose foods that promote the release of hormones that reduce hunger, help keep you satisfied, and make it easier to achieve a healthy weight.
Focus on whole foods that contain high-quality protein, healthy fat, and nutrient-dense fibrous carbs, especially vegetables.
And if you are really struggling to lose weight, stay away from high-calorie, high-reward foods that are easy to overindulge in, even if they are low in carbohydrates. Classic examples of such foods are cheese and nuts.
Rather than counting calories, make all of your calories count by eating nourishing, well-balanced low-carb meals.
Over a shorter period, calories can be stored as glycogen (carbohydrates). However, the maximum amount that can be stored is highly limited – only enough to last a day or two. ↩
You can find a large number of such studies here: