If you’re confused about whether calorie counting is effective, you’re not alone.
Some insist that counting calories is useful because they believe losing weight boils down to the concept of calories in versus calories out.
Meanwhile, others believe that calorie counting is outdated, does not work, and often leaves people heavier than when they started.
Both sides claim their ideas are backed by science, which only makes matters more confusing.
This article takes a critical look at the evidence to determine whether counting calories works.
What is a calorie?
A calorie is defined as the amount of heat energy needed to raise the temperature of 1 gram of water by 1°C.
Calories are normally used to describe the amount of energy your body gets from what you eat and drink.
Calories can also be used to describe the amount of energy your body needs to perform physical tasks including:
- maintaining your heartbeat
The amount of energy that foods provide is normally recorded in thousands of calories, or kilocalories (kcal).
For instance, one carrot generally provides you with 25,000 calories or 25 kcal. On the other hand, running on the treadmill for 30 minutes generally requires you to use 300,000 calories or 300 kcal.
However, because “kilocalories” is an awkward word to use, people often use the term “calories” instead.
For this article, the common term “calorie” will be used to describe kilocalories (kcal).
Summary: Calories are used to describe the energy your body gets from foods or expends on various activities.
How does your body use calories?
If you’re wondering why calories matter, it’s important to understand how your body uses them.
It begins with what you eat. Food and beverages are where your body gets the calories it needs to function. Those calories come from one of the three macronutrients:
- carbohydrates, also referred to as carbs
During digestion, your body breaks down the foods you eat into smaller units.
These subunits can either be used to build your tissues or to provide your body with the energy it needs to meet its immediate needs.
The amount of energy your body gets from the subunits depends on where they come from:
- Carbs: 4 calories per gram
- Protein: 4 calories per gram
- Fat: 9 calories per gram
- Alcohol: 7 calories per gram
Your body uses the calories produced from metabolizing these nutrients to power three main processes, which are listed below.
Your body will use most calories to perform basic functions, such as providing energy to your:
- nervous system
The amount of energy required to support these functions is referred to as your basal metabolic rate (BMR). This is sometimes referred to as Resting Metabolic Rate (RMR) because it effectively refers to the calories your body expends in a resting state for basic survival. BMR (or RMR) makes up the largest proportion of your total daily energy requirements.
Your body will use part of the calories you consume to help you digest and metabolize the foods you eat.
This is known as the thermic effect of food (TEF), and it varies based on the foods you eat. For instance, protein requires slightly more energy to be digested, whereas fat requires the least.
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About 10 percent of the calories you get from a meal will be used to support the TEF.
The remainder of the calories you get from foods fuel your physical activity.
This includes both your everyday tasks and your workouts. Therefore, the total number of calories needed to cover this category can vary greatly from day to day and person to person.
Summary: Your body gets calories from the foods you eat and uses them to fuel basal metabolic rate, digestion, and physical activity.
You need a calorie deficit to lose weight
Once your body’s immediate energy needs are met, any excess energy is stored for future use.
Some of it is stored as glycogen (carbohydrate) in your muscles and liver, and the rest of it will be stored as fat.
Therefore, if you eat more calories than your body needs, you will gain weight, mostly from fat.
On the other hand, if the calories you get from your diet are insufficient to cover your immediate needs, your body is forced to draw on its energy stores to compensate.
This state, known as being in a “calorie deficit” is what causes you to lose weight, mostly from your body fat. But keep in mind when too excessive calorie deficit occurs from dietary restrictions or heavy exercise, your body will also pull from protein stores —breakdown of muscle—in addition to burning body fat for fuel.
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This calorie balance concept has been proven time and time again and persists whether your calories come from carbs, fat, or protein.
Summary: To lose weight, you always need to burn more calories than you eat. This can occur through a combination of exercise and eating a balanced diet and food in moderation.
Not all calories are created equal
The seemingly simple question of whether calories from fat, protein, and carbs are different is controversial since it depends on how you look at it.
Just like inches and pounds, calories are a unit of measurement.
Therefore, purely in terms of weight loss, 100 calories will remain 100 calories regardless of whether they come from an apple or a donut.
However, in terms of health, all calories are not created equal.
It’s important to make the distinction between quantity and quality. Even foods that have the same quantity of calories can be of different nutritional quality and can have very different effects on your health. Furthermore, nutrient-dense foods such as fresh fruits and vegetables are linked to a lower risk of mortality.
In addition to their differing impact on health outcomes, different foods tend to affect your metabolism, hormone levels, hunger, and appetite differently.
For example, eating 100 calories worth of donuts may not diminish your hunger as effectively as eating 100 calories from apples due to the relative amounts of refined carbs, sugar, and fiber in the donuts.
Therefore, a donut may make you more likely to overeat later in the day, preventing you from achieving the calorie deficit needed for weight loss.
Summary: If you’re just looking at whether you’ll lose weight, a calorie is a calorie, and you’ll need to consume fewer calories than you burn. But in terms of health, and other factors that affect weight management such as hormones and appetite, not all calories are created equal.
Why it may seem like calories don‘t matter for weight loss
Biologically speaking, creating a calorie deficit is necessary for weight loss.
Still, many people claim that when you’re trying to lose weight, what you eat is more important than how much you eat.
This claim is generally fueled by studies in which participants on low carb diets appeared to lose more weight than those on high carb diets, despite eating as many or even more total calories.
At first glance, these studies seem to suggest that a calorie deficit is not needed for weight loss. They are often used as proof that calorie counting is useless.
However, several other factors may influence the results of these studies. Plus, low carb diets in addition to being difficult to sustain, evidence does not support them.
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People are bad at estimating what they eat
Many studies rely on self-reported data via participant food diaries rather than direct measurements to determine how many calories people eat or burn through physical activity.
Unfortunately, food and activity journals are not always completely accurate.
Studies report that participants significantly underestimate how much they eat and can underreport their calorie intake by as much as 2,000 calories per day.
Similarly, people tend to overestimate how much they move by up to 72%. This holds even in cases where participants are paid to be accurate.
According to one older study, even dietitians fall short when they’re asked to report their calorie intake accurately, although to a lesser extent than non-nutrition professionals.
Low carb diets are higher in protein and fat
Low carb diets are, by default, higher in protein and fat, which can make you feel fuller.
This helps reduce hunger and appetite and may cause participants on low-carb diets to eat fewer total calories per day.
Protein also requires slightly more energy to digest than carbs and fat, which can contribute to the energy deficit needed for weight loss, at least to a certain extent.
However, the slightly higher number of calories burned during protein digestion is unlikely to make a significant difference to your weight loss, according to some older studies.
Studies often measure weight loss rather than fat loss
Many studies only report the total amount of weight lost, without specifying whether this weight came from the loss of fat, muscle, or water.
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Low carb diets are known to reduce the body’s carb stores. Since carbs are normally stored together with water in your cells, lowering your body’s carb stores inevitably leads to water weight loss.
This may make it appear as though low-carb diets help participants lose fat more quickly than they do.
Studies controlling for these three factors put the myth to rest
To truly settle the debate on whether calories matter for weight loss, look at evidence solely from studies that control for the above three factors.
Such studies consistently show that weight loss always results from people eating fewer calories than they expend. Whether this deficit comes from eating fewer carbs, protein, or fat makes little difference.
Summary: Certain factors help explain why calories can seem irrelevant to weight loss. However, studies controlling for these factors consistently show that a calorie deficit is still needed for weight loss.
Why counting calories generally works
Counting calories is a time-tested way to lose weight.
Many studies show that recording your food intake and physical activity are very effective ways to help lose weight.
A recent review reports that weight loss programs incorporating calorie counting led participants to lose around 7 pounds (3.3 kg) more than those who did not. It seems that the more consistently you record your intake, the better.
For instance, one study involving 272 people found that those who monitored their food intake, physical activity, and body weight more frequently experienced greater weight loss.
There are three reasons why calorie counting likely works:
- Tracking your calories can help you identify which eating patterns you need to be mindful of to successfully lose weight.
- Despite its lack of precision, being aware through tracking of what you eat can give you an approximate baseline to work from and compare with when you’re trying to reduce the total number of calories you eat per day.
- Finally, keeping track of what you eat can help you monitor your behavior. This may help keep you accountable for the daily choices you make and motivate you to continue progressing toward your goals.
That said, it’s important to note that calorie counting is not a requirement for weight loss.
What matters is your ability to create and sustain the energy deficit needed to lose weight. However, calorie counting can be a useful tool for achieving this energy deficit.
Summary: Counting calories can help you lose weight by bringing awareness to what you eat each day. This can help you identify eating patterns that you may need to modify, keeping you on track to reach your goals.
The best ways to keep track of what you eat
If you’re interested in counting calories, there are several ways to go about it.
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All involve recording what you eat, whether on paper, online or in a mobile app.
According to studies, the method you pick does not matter, so it’s most effective to pick the one you prefer.
Using scales and measuring cups can also be beneficial for helping you measure food portions more accurately.
You might also want to try using the following visual guidelines to estimate your portion sizes. They’re less accurate but useful if you have limited access to a scale or measuring cups:
- 1 cup: a baseball or your closed fist (appropriate for raw or cooked vegetables)
- 3 ounces (90 grams): a deck of cards or the size and thickness of the palm of your hand minus the fingers (appropriate for measuring meat, poultry, and fish)
- 1 tablespoon (15 mL): a lipstick or the size of your thumb (can measure nut spreads)
- 1 teaspoon (5 mL): your fingertip (can be used to measure oils and other fats)
Finally, it’s worth mentioning that counting calories only allows you to evaluate your diet from a quantity perspective. It says very little about the quality of what you eat.
When it comes to health, 100 calories from apples will affect your health differently than 100 calories from donuts.
Therefore, it’s important to avoid picking foods solely based on their calorie content. Instead, make sure you consider their vitamin and mineral content as well.
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You can do this by filling your diet with whole, minimally processed foods, such as fruits, vegetables, whole grains, lean proteins, nuts/seeds, and beans/legumes.
Summary: To count your calories most accurately, use a food journal combined with scales or measuring cups.
Are there downsides to counting calories?
Although tracking your calorie intake can be an effective tool for weight loss, it might not be suitable for everyone.
In particular, it may not be recommended for those with a history of disordered eating, as it could foster an unhealthy relationship with food and worsen symptoms.
According to one study involving 105 people diagnosed with an eating disorder, 75% reported using an online tool to count their calories and 73% noted that they felt this contributed to their eating disorder.
In another study, counting calories and self-weighing more frequently was linked to increased eating-disorder severity among college students.
Several studies have had similar findings, which suggest that weighing your food or using calorie or fitness trackers could contribute to unhealthy eating habits in some people.
Therefore, if you find that counting your calories or tracking your food intake leads to feelings of guilt, shame, or anxiety, it may be best to discontinue these practices.
Practicing intuitive eating, which involves listening to your body and eating when you feel hungry, which may also be a better alternative for those with a history of disordered eating.
Summary: Counting calories could worsen eating-disorder symptoms in some people and contribute to an unhealthy relationship with food.
To lose weight, you need to eat fewer calories than you burn.
Some people can do this without actually counting calories. Others find that counting calories is an effective way to consciously create and maintain this deficit.
Those interested in giving calorie counting a try should keep in mind that not all calories are the same when it comes to impact on health, as well as other factors that affect weight loss such as appetite and hormones.
Therefore, make sure to build your menu around minimally processed, nutrient-rich foods and rather than base your food choices on calories alone.
Additionally, keep in mind that counting calories could contribute to an unhealthy relationship with food, especially for those with a history of eating disorders.
If you find that tracking your calorie intake triggers any negative feelings like guilt or shame, consider other practices instead, such as intuitive eating.
Talk with a healthcare professional to help determine if calorie counting is right for you and your needs.