“Calories in, calories out” is a popular concept that suggests that as long as you burn more calories than you consume, you will lose weight. But is it really that simple?
For decades, this concept has been the go-to for weight loss advice. It’s the foundation of many diets and fitness programs. But despite its popularity, many people struggle to lose weight despite religiously reducing calories and watching how much they eat.
The “calories in, calories out” concept is oversimplified and flawed. There are many factors that influence weight loss, and reducing it to a simple equation ignores the complexity of our bodies and the science of weight loss. In this article, I will explore why this approach doesn’t work and what you can do instead to achieve sustainable weight loss.
What Calories Actually Are?
Calories — or joules — are a way to measure heat energy. Heat energy is how energetic the electrons in something, like water, are. This energy gets transferred between electrons using electromagnetic waves called photons, which don’t weigh anything. We feel this energy transfer as heat.
Calories are not the same thing as the physical work our body does. While calories are a measure of energy, our body’s processes are more complex than converting heat energy to body energy.
The measurement of heat energy is appropriate for use in fields like physics and chemistry. However, regarding the complex biochemical digestion your human body performs on food, using calories is not representative of reality.
So, calories might make sense when talking about heating up water or calculating energy in physics and chemistry. But when it comes to the complex biochemical digestion in our bodies, the calorie has nothing to do with any of that.
The Origins of Calorie Counting
Decades ago, some scientists sought to describe how we use energy in our food. They started using the concept of calories in this regard. They would put food in a small oven called a bomb calorimeter, burn the food, and determine how much the water surrounding the oven heated up. This process may be suitable for burning bacon or bread in a tiny oven, but it doesn’t correlate with how your body processes the food you consume.
They used this method to come up with data for various foods like bacon, avocado, and bread. Soon, we had detailed charts and graphs about the calories in different foods.
Your body doesn’t burn calories — let alone has no idea what a calorie is — and it doesn’t definitely count them. Each macronutrient (fat, protein, and carbohydrates) is digested and metabolized using different biochemical pathways, none of which involve calories.
Energy Conversion Limitations
I’d like to emphasize that calories are explicitly a measurement of heat energy. While there’s a mathematical way to convert one form of energy to another, it requires an actual mechanism to transfer energy from one form to another in the real world.
The human body cannot collect heat and use it for metabolic processes. Heat is expressed through the energetic state of electrons and their transferring of energy through photons, but we cannot collect these photons for metabolic processes.
We’re often told that “calories in, calories out” is a good tool for predicting weight changes over time. However, controlling calorie intake doesn’t mean controlling energy intake. When controlling the amount of food eaten, we’re actually controlling the mass that goes into the body. The only thing that affects weight is the balance of mass in and mass out.
Moreover, estimating how much energy we genuinely expend during activities and basal metabolic rate is almost impossible. Calories in and calories out remain to be an unreliable way of determining one’s weight changes.
Mass vs Energy
When we talk about controlling our body weight, it’s important to understand the difference between mass and energy in our body.
Our bodies can’t use heat energy, i.e., calories (photons), for fuel. When we control how much we eat, we’re really controlling how much mass we put in our bodies.
When we eat less food, we put less stuff (mass) into our bodies, which can help us lose weight. What matters for our weight is the balance between the mass we put in and the mass we use up. This means that our weight is influenced by how much mass we keep in our body, not by how much heat energy we absorb or release.
Instead of counting calories, we should focus on controlling the amount (mass) of food we eat.
Inaccuracies in Calorie Estimates
As our weight is affected by how much mass we put in and how much we use up, this means that using calorie estimates to measure how much energy is in our food is inaccurate.
So, the common estimates of 9 calories per gram of fat, 4 per gram of carbohydrate, 4 per gram of protein, and 7 per gram of alcohol aren’t very precise. This is because everyone’s body processes food differently, and the actual energy we get from food can vary depending on many things.
Just think of type 1 diabetics: if they don’t take insulin, they can eat whatever they can, as much as they can, without gaining a single ounce of weight (but they’ll get tons of other health problems). For them, it’s definitely not calories in, calories out. Hormones play a much bigger role in weight management than calories.
I can also give an example of myself: I fasted for 7 days, only consuming water and calorie-free electrolytes. During the 7 days, I didn’t lose a single ounce of weight even though I didn’t get a single calorie in my system.
Thermic Effects of Food
Did you know that different macronutrients have different thermic effects? This means that different types of food require different amounts of energy to digest and process. This is called the thermic effect of food (TEF).
The thermic effect of food is the increase in metabolic rate that occurs after eating. Age, physical activity, meal timing, etc., may also play roles in TEF, but the macronutrients also play an important role as different macronutrients have different thermic effects:
- Protein: Protein has the highest thermic effect of all the macronutrients, meaning that it takes more energy to digest protein than it does to digest carbohydrates or fats. According to some studies, protein can increase energy expenditure by up to 30%.
- Carbohydrates: Carbohydrates have a lower thermic effect than protein, but they still require energy to digest and process. The type of carbohydrate can affect its thermic effect, with high-fiber carbohydrates having a higher effect than low-fiber carbohydrates.
- Fats: Fats have the lowest thermic effect of all the macronutrients, meaning that they require the least amount of energy to digest and process.
Also, in this light, calorie counting doesn’t work as your body needs to work harder to digest and process protein than, for example, fat.
You Don’t Want to Lose Weight, You Want to Lose Body Fat (and Excess Water)
People often say they want to lose weight when in truth, they want to lose fat. When following a low-carb diet, you actually might not lose much weight, especially if you are not obese. However, your body composition changes.
In fact, you lose fat and gain muscle on a low-carb diet, even if you don’t exercise and do weight training.
Moreover, carbs retain water in your body. When you consume carbohydrates, they are broken down into glucose and stored in your liver and muscles as glycogen. For every gram of glycogen stored in the body, approximately 2—3 grams of water are retained.
This is because glycogen is stored in a hydrated form, with each glycogen molecule bound to water molecules. Therefore, when your body stores glycogen, water is also stored along with it, leading to water retention.
Also, inflammatory foods like sugar and vegetable oils can make you retain water. This is called edema. Chances are that if you eat a high-carb inflammatory diet (or a low-carb inflammatory diet whatsoever), your body has more fat and water than it should.
If you eat a super salty meal (especially if it’s salted with table salt, i.e., pure sodium chloride), your body also retains water. A salty meal makes you thirsty because you need to balance your blood pressure by drinking lots of water.
No matter what causes your water retention, it means that you weigh more
When you consider these facts, counting calories doesn’t work for managing your weight because it does not consider the thermic effect of food and water retention from eating carbohydrates, inflammatory foods, or foods salted with table salt.
In conclusion: losing fat (and excess water) rather than weight is a more specific and healthful goal because weight loss can come from various sources, including muscle loss in addition to fat loss. Losing muscle can lead to a decrease in metabolic rate and can make it more difficult to maintain ideal weight over time.
Of course, you also want to get rid of excess water, but you don’t want to get dehydrated. Moreover, losing water weight can be temporary and can be easily regained.
Losing excess fat leads to improved body composition, better health outcomes, and more sustainable weight management over time.
Why Calorie Counting Always Fails: Two Examples
Weight Watchers: The Weight Watchers diet is often promoted as one of the best diets in the world, but it is not the best approach for long-term weight loss. Counting calories is not sustainable, and obesity and being overweight are hormone problems, not calorie problems.
How many people you know have got long-term success with Weight Watchers? I bet you can count them with the fingers of one hand. Weight Watchers is a good business but a bad method to lose weight.
Women’s Health Initiative study: The Women’s Health Initiative study involved thousands of women and compared a group of women who followed a calorie-restricted diet with those who did not. At the end of the study, the women who restricted their calorie intake did not lose any more weight than those who did not.
Both these examples show that counting calories is ineffective for weight loss. Instead, obesity is a hormonal issue that can be addressed by cutting back on carbohydrate consumption. The ketogenic diet and intermittent fasting address the hormone issue by limiting carbohydrate intake, likely to provide better long-term results in weight management and overall health.
- Calories measure heat energy, not how much physical work our body does.
- Our body’s weight is affected by how much stuff (mass) we put in and how much we use up, not just by calories.
- The calorie counts for different foods and how much energy we use daily are inaccurate. This is because our body processes food and uses energy in a more complex way than just counting calories.
- Carbohydrates and inflammatory foods tend to retain water in your body, leading to weight gain.
- Different foods have different thermic effects, meaning they require different amounts of energy to digest and process.
- Reducing carbs and eating a clean low-carb, ketogenic, or carnivore diet to satiety is a much better approach for healthy weight management than calorie counting.
- The ketogenic diet and intermittent fasting address the hormone issue behind weight problems by limiting carbohydrate intake, likely to provide better long-term results in weight management and overall health.
Calories are a measurement of heat energy, but our body can’t use heat energy for energy to keep us alive. Measuring calories works in a lab, but it’s a flawed measurement in the context of a human body, as we are not combustion engines but enormously complex creatures.
Counting calories to predict weight changes is unreliable because it’s difficult to know how much energy we use up during the day. Additionally, calorie counting does not take into account the thermic effect of food and water retention from eating carbohydrates and inflammatory foods, which can lead to misleading weight gain.
Reducing carbs and eating a clean low-carb, ketogenic, or carnivore diet to satiety is a much better approach for healthy weight management than calorie counting.
Videos about the topic:
- Bart Kay, “In 5-Mins or Less – CICO (calories in, calories out)…“
- Jonathan Griffiths (Composition Consultant), “Calories in vs calories out?
- Jason Fung on Keto Kamp, “Does Counting Calories to Lose Weight Work? With Dr Jason Fung”
- Dr. Ken Berry, “Counting Calories is Stupid”