Why Calories in vs. Calories Out FAILS

Happy Friday and welcome back! I am super excited to talk about this topic as there are SO many discussions and opinions about it. Hope you enjoy reading and definitely share your story with calories below 🙂

I have been confronted with calories a lot when I was into fitness and during and after my fitness competition shows I used to track my calories. And for years I was convinced that calories in vs calories out is the key to being healthy! But damn I learned a lot since then. So let me ask you: Do you believe that a 100kcal chocolate bar and a 100kcal banana are equally healthy ??

What is the calories in vs. calories out theory?

The calories in vs. calories out theory is known commonly in the health and fitness industry as IIFYM (if it fits your macros), a way of eating that solely focuses on how many calories are consumed and how many are metabolized through exercise.

However, other than IIFYM, the majority of diets you see in the health and fitness industry are based on the same calories in vs. calories out theory.

This theory argues that if you intake more energy (through food) than you expend (through exercise and daily movement), you will gain weight. If you intake less energy than you expend, you will lose weight. It’s all about energy balance.

But why does it fail?

In June 2011, Barry Popkin and Kiyan Duffey, doctors at the University of North Carolina at Chapel Hill, made a startling discovery. They discovered that the number of calories consumed per person per day increased by 570 calories between 1977 and 2006. So if the calories in = calories out theory were true, it would mean if an average person consumes 570 more calories per day, then the average person should have gained 476 pounds since 2006, right? But we know that can’t be true.

We should think about our weight in terms of biology, not math. If we drink more, we urinate more. If we inhale more, we exhale more. When we eat more, our body burns more. It is proven that people who eat more have a higher metabolic rate. And this advantage is not solely theirs because you can also improve your metabolism or “heal” it after chronic dieting or an eating disorder when you start to eat enough calories. Your metabolism is suppressed by dieting and restriction, and that’s why you may gain weight initially when you start to eat more, but you will drop the excess weight when the damage from your past bad eating habits is repaired and your bodily functions – hormones, hunger cues, metabolism – are back to normal.

Just as the body knows how to breathe unconsciously, it knows how to keep our weight within a normal range.

We just have to follow our hunger cues and not mess with the system by dieting, restricting calories or foods, or trying to “burn off calories.” If your body is healthy and not riddled with a history of disordered eating habits, it easily stays at its set-point weight without you having to think about it…or calculate if you can or cannot eat that cookie today and how many steps you have to take to burn it off.

Studies show traditional calorie-counting approaches failing 95.4 percent of the time.

This “burn more when we eat more” behavior explains how we’ve gained dramatically less than what would be predicted by calorie math. The “burn less when we eat less” behavior explains why studies show traditional calorie-counting approaches failing 95.4 percent of the time – and often provoking even greater rebound weight gain. When we put these two biologic behaviors together, we can see why every weight-loss study ever conducted shows that when people are given a surplus or shortage of calories, they never gain or lose the mathematically anticipated amount of fat. The body just doesn’t work that way.

Carbohydrates are sugars that come in two main forms — simple and complex — depending on its chemical structure. Sugars can be categorized as single sugars (monosaccharides), including glucose, fructose and galactose, or double sugars (disaccharides) which include sucrose, lactose and maltose. Fructose is the sugar you find in fruit, sucrose the table sugar you put in your coffee and glucose is found in carbohydrates like breads and pasta once they are broken down. The chemical molecules of the glucose, fructose and sucrose found in high fructose corn syrup (HFCS) are the exact same chemical molecules as the ones found in fruit. But they are metabolized differently by the body, which makes all the difference. Glucose is metabolized by all of your body’s tissues whereas fructose can only be metabolized by the liver.

The less people ate, the more body fat they had.

According to the calories in calories, calories out theory, we should lose weight if we just eat a little bit less, right?

Here’s another study conducted at Harvard involving 67,272 people. The researchers divided this large sample into five groups according to the number of calories they ate and found that the fewer people ate, the more body fat they had. People who weighed more ate far fewer calories than people who weighed less naturally – these people simply burned more calories. So this study clearly shows that lowering your calories does not matter in terms of your weight. If you slow down your metabolism by dieting and lose muscle tissue, it’s a sure way to eat less and weigh even more in the long run.

Jonathan Bailor, the author of A Calorie Myth: How to Eat More and Exercise Less with The Smarter Science of Slim, writes:

Let’s look at a real-life study: the Women’s Health Initiative, a study that tracked nearly 49,000 women for eight years. Just as in our experiment, the women in one group ate an average of 120 fewer calories a day than the other group. Remember, that adds up to 350,400 fewer calories. How much lighter was the average woman who ate 350,400 fewer calories? The answer: 0.88 pounds. 

That is not a typo. Eating 350,400 FEWER calories had less than 1 percent of the impact predicted by calorie math. Eating less of a traditional Western diet does not cause a long-term fat loss because this approach incorrectly assumes that taking in fewer calories forces our body to burn fat. That has been clinically proved to be false. Eating less does not force us to burn body fat. It forces us to burn fewer calories.
It get’s worse, if we don’t have enough energy, our body burns muscle, not fat. Studies show that up to 70 percent of the non-water weight lost when people are eating less comes from burning muscle – not body fat.

Foods affect our hormones, which can affect how we use or store energy

Ghrelin, the hunger hormone, tells your brain when to eat and when to stop eating. Fructose increases ghrelin levels meaning it stimulates hunger despite satiety, which can not be stimulated by glucose. Glucose produces increases in circulating satiety hormones, making you feel full and to stop eating, whereas fructose does not.

Our bodies burn different amounts of energy during digestion of macronutrients

Within the total amount of calories you burn in a day — known as your total daily energy expenditure (TDEE) — 15 percent accounts for the calories burnt during digestion. This is known as the thermic effect of food (TEF).

Protein has the highest thermic effect of any macronutrient, raising your metabolic rate by up to 30 percent. Carbs have the second highest — 5 to 15 percent are burnt, largely depending on whether they are complex or refined, and fat has the lowest — with less than 5 percent being burnt during metabolism.

We need to count chemicals instead of calories

Processed foods filled with chemicals are known endocrine disruptors — hormonally active agents — meaning they cause hormonal imbalances, increase disease risk and prevent your body from maintaining homeostasis.

As well as this, processed foods are linked to overeating, those on a processed diet eat on average 500 calories more when given the chance to snack outside of meals, compared to the group who ate a wholefood diet of the same macros.

Processed foods are also associated with obesity, type 2 diabetes, cardiovascular disease, high LDL cholesterol, mental health illness, neurological decline and all cause mortality. Even when researchers adjust for calorie intake and other confounders like smoking and exercise activity.


Your low calorie low fat protein bar is worse than eating salmon and rice, even if the salmon and rice is more calories, because the way you METABOLIZE the processed foods is different and will be stored more readily as fat rather than effectively burnt as fuel.

That doesn’t mean you can start gorging on thousands of calories of healthy food to try and lose weight; a deficit is still essential. However, switching out your healthy meals for lower calorie processed alternatives is not a good way to go.

As you can see, there’s a lot more to food than just their caloric density: the way they are metabolized, the hormonal response they stimulate, their glycemic index and so much more. Moreover, it’s clear that calories in vs. calories out isn’t the whole picture, and can’t be relied upon.

My recommendation as a Health Coach

I would recommend you to listen to your body as it knows best when its full. Calorie counting made me lose my sense for my hunger feeling and I was only eating when its time or how ever many calories were on my plan. But also we burn different on different days, we sleep different and we feel different and therefore we need a different amount of calories every day! Learn to listen to your body.

When I work with clients it is our goals to reach a fiber intake of at least 30g/ day and a variety of 30 different natural products containing fiber/ week. Fiber is not metabolized in calories PLUS it is the most important ingredient for holistic health! No matter if you want to lose weight or keep is, fiber is your best friend!

I am now here to help you on your journey to healthy eating habits. No matter what your goal is, I show you how to get there 🙂

As a Health Coach, I am mentoring my clients to create and maintain long-term lifestyle changes to enhance their overall quality of life. In addition to supporting clients with specific goals, I empower my clients to choose health-promoting behaviors that work for them. I raise awareness and offer support as clients move in their own bio-individual ways toward the greater health they want for themselves. My coaching hopefully leads to long-term behavior change, but only because I help my clients do the meaningful work that forms a strong foundation.

How can I help you? Are there any changes you wish for yourself? Is your health the best it could be? You can book your free consultation with me now: