Most people want to be told what magic foods to eat, or what diet to follow in order to lose weight. They believe that there are certain foods they need to eat in order to lose fat and certain foods they need to avoid to prevent weight gain. You hear it all the time: when people try to lose weight, they try to “eat healthy” and avoid “junk food.” Although doing so is probably a good idea for weight loss, the specific foods you eat are not what dictates whether you gain weight or lose weight.
There are basic scientific principles that dictate weight change. Once you understand the principles that govern whether someone gains or loses weight, it will be easy to understand why people succeed to lose weight on different diets like keto, paleo, low-fat, amongst others; and at the same time, other people fail to lose weight on those same exact diets.
In other words, eating an apple won’t make you lose weight because it’s “healthy,” the same way that eating a piece of candy won’t make you gain weight because it’s “junk food.” The variables that influence weight gain or weight loss are complex. However, they can be summarized into a concept that we call energy balance.
What is energy balance … and how does it relate to fat loss?
Changes in your body weight, whether it’s gaining weight or losing weight, boils down to the concept of energy balance. The reason that all diets can result in weight loss is because of this concept. The funny thing is that even some of the most prominent sources of nutrition information get this basic concept wrong.
Ok, let’s explain what energy balance is and what it’s not.
Your body is a biological system that interacts with an external environment. Your body can acquire energy from its external environment, and it can also release energy. The energy coming into your body comes from the food you eat. One the other hand, the energy leaving your body is the energy that your body uses on a daily basis to keep you alive, regulate your body temperature, and move around. In the simplest of terms, energy balance is the balance between how much energy enters your body, which we call energy intake, and how much energy leaves your body, which we call energy expenditure.
Counting calories for fat loss
The amount of energy coming in or out of the body is usually reported in calories, which is simply a unit of measurement for energy. The same way that meters are a unit of measurement for length, pounds are a unit of measurement for mass, and Fahrenheit is a unit of measurement for temperature; Calories are a unit of measurement for energy. In other words, calories are not an actual physical thing that you find in food, instead, it’s the unit we use to report how much energy is in a particular food.
If your energy intake surpasses your energy expenditure, your body doesn’t just let the excess energy go to waste. Instead, your body will store the excess energy as body fat, which results in weight gain if sustained over a prolonged period of time.
This is what we call being in a positive energy balance.
On the other hand, if your energy intake is less than your energy expenditure, your body has to make up for the difference by tapping into stored energy sources since you’re not getting the sufficient amount of energy you need from your diet. The stored energy mainly comes from stored body fat. Therefore, if you consume less energy than your body expends over a prolonged period of time, you lose weight because your body is “burning up” body fat to meet its energy requirements.
This is what we call being in a negative energy balance.
Lastly, if your energy intake precisely matches your energy expenditure, your body weight will remain stable. That’s it - the concept of energy balance is really that simple!
What about special diets or foods?
As previously mentioned, energy balance is the variable that explains why different diets are effective for weight loss. Whether someone loses weight following a ketogenic diet, intermittent fasting, or literally any other diet, they did so because they created an energy deficit.
In other words, if someone loses weight, it simply means that the total amount of energy they consumed was less than the amount of energy they expended over time, independent of what type of diet they followed.
The exact same logic is true for weight gain, only in reverse. If someone gains weight, it means that the total amount of energy they consumed was more than the amount of energy they expended over time, regardless of what type of foods they ate.
This is why weight gain or weight loss is not determined by the particular foods you eat, but instead by the total amount of energy consumed in comparison to the total amount of energy your body expends.
Using this logic, you can start to understand why comments like “sugar, carbs, or (insert any food here) makes you fat,” actually don’t make any sense. You cannot blame weight gain on one particular food without accounting for how much total energy you are consuming.
A common myth about fat loss, disproved
Some people use the fact that they “don’t eat much” and can’t lose weight as a reason to try and disprove that energy balance isn’t the most important variable dictating weight change. We've even heard people say things like "I only eat 1200 calories per day and can’t lose weight, calories don’t matter."
However, this is fundamentally false.
It could be that this person, for whatever reason, may also have very low energy expenditure (energy leaving the body), which impedes them from losing weight. It could also be that, even though they’re not eating a high volume of food, most of the foods they eat are very energy dense. Therefore, they’re still eating a lot of calories (more than they realize.) Lastly, and most likely, is that they’re tracking their caloric intake incorrectly and they’re actually consuming well above 1200 calories per day.
If someone isn’t losing weight then, by definition, they’re not in a negative energy balance. That does not negate the fact that they may be eating a low volume of food and may still be struggling to lose weight.
Even prominent sources of health information get this concept wrong. In this article from Healthline, a huge source of health-related content, it states that "calories in calories out" is the biggest nutrition myth because it doesn’t account for variables like hormone imbalances and diet quality.
While it’s true that there are many reasons why someone may have low energy expenditure, including being a small person, being physically inactive, as well as having certain medical conditions that influence their body’s energy expenditure, this doesn’t negate energy balance.
Energy balance simply refers to the balance between energy intake and energy expenditure. It is NOT a fixed number of calories.
Let’s use some extreme examples to demonstrate this relationship. If you starve absolutely anyone to death, they will lose weight and waste away independent of their physical activity or hormone concentrations. On the other hand, if absolutely anyone ate like 75 apples per day, they would gain weight because they would be eating approximately 7500 calories, which is a lot of energy from food.
The first example is showing that if you don’t eat, then you waste away because you’re simply not getting any calories from your diet. On the other hand, the second example is showing that even if you eat “healthy foods” like apples, you can gain weight if you have enough of them.
Other important factors for fat loss and energy balance
At this point you should understand the basic fundamentals of energy balance. It’s easy, right?
Eat more calories than you burn, you gain weight.
Eat fewer calories than you burn, you lose weight.
However, the concept of energy balance can be taken a step further by discussing the variables that influence both energy intake and energy expenditure.
Remember how we said earlier that you can’t blame weight gain on any particular food? This is true. However, the foods you eat can influence how much you eat, which in turn influences your energy intake. For example, it’s practically impossible to eat 75 apples because they’re high in fiber and very satiating. You would feel like your stomach is going to explode.
In general, whole unprocessed foods are more filling, nutritious, and less calorie dense than highly processed foods like cake or cookies, which are freaking delicious and easy to overeat. This is why following a “healthy” diet can make weight loss easier. It’s because foods like vegetables, fruits, and lean meats help keep you fuller for longer and they don’t contain as many calories. However, you don’t have to be perfect. Focusing on the 80/20 rule, try to eat whole unprocessed foods about 80% of the time.
There are also many variables that influence energy expenditure including genetics, size, and physical activity. Of these, our physical activity is the one we have the most control over. Living a physically active lifestyle will make it easier to maintain a healthy body weight. We're not just talking about formal exercise, but also getting regular movement throughout the day like walking the dog, taking the stairs at work, and going outside to do some gardening.
The reason eating a healthy diet and moving around helps with weight loss is because of… say it with us... energy balance! Eating a healthy diet and being physically active makes it way easier to be in negative energy balance compared to eating junk food and being sedentary.
Next steps for fat loss
All right, you may be thinking “all this sounds great, but how do I know how many calories I should be eating to lose weight?” This varies by individual. Now that you understand the concept of energy balance, learning how many calories you should be consuming for your physique goal is the next logical step. Click here to learn how to calculate your specific caloric requirements.