Should you count calories on a low-carb or keto diet?

By Franziska Spritzler, RD, CDE, medical review by Dr. Bret Scher, MD – Updated July 10, 2020  Evidence based

When it comes to weight, calories are often talked about but frequently misunderstood. Indeed, whether counting calories is actually useful for weight loss is debatable. Read on to learn about calories and their role in weight regulation on low-carb and keto diets.

1. What are calories?

2. How many calories do carbs, protein, and fat provide?

3. Calories count, but they are not the whole story

4. The bottom line

What are calories?

A calorie is a unit of energy 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

Even though fat provides more than twice as many calories as carbs,  you may have noticed that it’s much more filling.

Protein is generally considered the most satiating macronutrient, but it’s mostly used for cell repair and muscle maintenance.

It’s not very effective as an energy source because it must first be converted to glucose in the liver in order to be used as fuel. Eating extremely high amounts of protein isn’t necessarily a good thing and may reduce the effect of a strict low-carb diet. Learn more 

Calories from pure fats such as butter, ghee, lard and most oils are 100% 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. 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. Therefore, some contend that calories are all that matter. 

All you have to do to lose weight is reduce calories.

It sounds simple, but it appears humans are more complicated than that.

There’s far more to weight regulation than just monitoring calories in vs. calories out. 

 Indeed, most members of the human race appear to have regulated their weight effectively for millennia, before anyone even knew what a calorie was.

The modern obesity epidemic seems to be an unprecedented phenomenon, and it coincides with an ever-increased focus on counting calories. 

 Correlation is not causation, so it would be wrong to say that counting calories causes obesity. However, at best, counting calories seems to be an imperfect aid to weight control. So what’s really going on? As it turns out, hormonal regulation may be the key.

Hormones play a large role in influencing appetite, fullness, and fat storage. 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.

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.

Additionally, your insulin levels – and how sensitive your body is to insulin – may influence whether you store or burn calories. In people who have lost weight, elevated post-meal insulin levels and a slower metabolism may drive weight regain. However, researchers have found that decreasing carb intake may help counteract these effects.

Calories count, but you don’t have to count them.

– Dr. Eric Westman, MD

What’s more, low-carb diets regularly outperform low-calorie diets for weight loss, even in studies where calories aren’t intentionally counted or restricted during low-carb eating.

For example, 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. Yet the participants lost more weight and body fat during the low-carb week than the low-fat week – even though men in the study averaged slightly higher calorie intake while following low carb.

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While calories are ly important in weight regulation, they are one factor that need to be considered within the context of hormones and human behavior.

Video: Doctors answer

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More Q&A videos with doctors 

Counting calories: yes or no?

Diet Doctor, don’t recommend counting calories. Firstly, 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. We feel it’s far more important to choose foods that promote the release of hunger reducing hormones that help keep you satisfied and make it easier to achieve a healthy weight.

Focus on minimally processed foods that contain high-quality protein, healthy fat, and nutrient-dense fibrous carbs, especially vegetables.

And if you’re 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.

Franziska Spritzler, RD