Can calorie counting help you lose weight?
The short answer is:
But calorie counting is not the exact science that many people believe it to be. It works for reasons you might not expect.
To understand why let’s start with the basics…
What is a calorie?
The amount of energy in an item of food or drink is measured in calories.
To maintain our weight, the amount of energy we put into our bodies must be the same as the amount of energy we use through normal bodily functions and physical activity.
As the first Law of Thermodynamics states:
In a closed system, energy can neither be created nor destroyed, it can only be changed from one form to another.
In other words:
Because energy from food and drink cannot simply disappear, if we consume more calories than our body needs then we will gain weight and if we consume less then we will lose weight.
Is a calorie always a calorie?
Given this fact, you might expect that losing weight is simply a matter of tracking the number of calories we consume and the number of calories we burn and ensuring there is a deficit.
This is otherwise known as ‘calories in’ vs ‘calories out’.
But both the ‘calories in’ and ‘calories out’ sides of the equation have flaws that can make calorie counting wildly inaccurate.
On the ‘calories in’ side:
- Calorie counts are imprecise. The calorie counts on food labels are averages. Research shows that the true calorie content of what you’re eating is often significantly higher or lower.
- We don’t absorb all of the calories we consume. Some calories pass through us undigested, and this varies from food to food. Moreover, our own individual gut bacteria can increase or decrease the calories we absorb.
- How you prepare food changes its calorie load. Cooking your food generally makes more of the calories available for absorption and food labels don’t always reflect that.
- People are bad at estimating portion sizes. Studies show that people mismeasure portions about two-thirds of the time, so it’s easy to consume more calories than we intend to.
And on the ‘calories out’ side:
- Devices that estimate calorie burn are imprecise. Consumer fitness trackers are off by about 30% for total daily calorie expenditure and between 9% and 23% for aerobic exercise.
- Individuals burn calories uniquely and variably. Hormones, genes, and sleep all affect our energy expenditure.
- What and how much you eat influences how many calories you burn. When you eat 100 calories of protein, for example, 20-30% of those calories will be burned via digestion meaning only 70-80 calories ‘count’ (for carbs it is 5-10% and for fats it is 0-3%).
- Your weight history influences how many calories you burn. If you’ve ever been overweight or obese then your metabolic rate may be lower than equations predict due to something called adaptive thermogenesis.
So why bother counting calories?
Given that calorie counting can be so inaccurate, you might be thinking that it’s a waste of time.
And yet, study after study shows that those who count calories lose more weight than those who don’t. A meta-analysis from 2014 found that weight loss programs incorporating calorie counting led participants to lose around 7 pounds (3.3 kg) more than those that did not.
While calorie counting might not be an exact science, it clearly still works.
There are three likely reasons why:
- It’s eye-opening. Studies show that people are bad at estimating how many calories are in their food. Even dieticians get it wrong. Even if they’re not perfect, food tracking apps provide more reliable information on how many calories you are consuming.
- It gives you a reference point. Despite its lack of precision, being aware of what you eat through tracking 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.
- It provides accountability. Keeping track of what you eat can help you monitor your daily choices and motivate you to continue progressing toward your goals.
The bottom line
In order to lose weight, you need to consume fewer calories than you burn.
And while far from an exact science, calorie counting is still the best tool to help you get your food intake into the right ballpark.
It helps you understand your current dietary habits and provides a baseline from which you can make adjustments.
But it’s not something you need to do forever.
Calorie counting is best thought of as a tool to ‘calibrate’ your food intake. Once you have a feel for how many calories certain foods contain and how much you should be eating you can stop calorie counting and return to it a few months later to ‘recalibrate’.
Images
1. Photo by Artur Łuczka per Unsplash