The Mathematics of Weight Loss: The Illusion of Simplicity

In a world obsessed with quick fixes and fast diets, understanding the fundamental equation of weight management can be empowering. The key lies in the relationship between calories consumed and calories burned, a concept often oversimplified or misunderstood. In this post, we dive into the practical aspects of this equation, shedding light on the common misconceptions surrounding weight loss.

The Caloric Balance Equation:

Let’s begin by presenting a straightforward equation that dictates weight changes: calories absorbed - calories spent. If the result is greater than zero, it means weight gain; less than zero implies weight loss, and zero denotes no change in weight. While the equation seems simple, the nuances lie in the variables involved.

To illustrate this concept with a practical example, let’s consider a common goal: losing 5 kg of fat before summer. Each kilogram of body fat roughly equals 7500 kcal. By maintaining a daily energy deficit of 250 kcal, achievable through small adjustments in diet or exercise, one could lose a kilogram in about a month. To put it into perspective, 250 kcal is akin to a slice of pizza, or two cans of cola, or three slices of cheese, or an apple and a banana.

Despite the apparent simplicity of the weight loss concept, many find themselves struggling. The reason behind this struggle lies in the individual variability of the equation's terms and their interdependence.

At any time, the brain plays with the terms of this equation in the attempt of maintaining balance. The brain plays a pivotal role in adjusting calorie intake and expenditure to keep the equation in check.

Again let’s use a practical example. When a person goes on a diet (negative calorie balance) they in fact mean to minimize the calorie intake term of the equation, assuming that the calorie expenditure term should stay the same. Nothing is less true. The brain reacts to the decrease in calorie intake and tries to reestablish balance. It does so in two main ways: it triggers hunger to promote calorie intake (the person feel hungry) and it decreases calorie expenditure to buffer the calorie deficit (the person feels tired). Of course each person's metabolism is unique, influenced by factors such as age, genetics, and lifestyle and the entity of this reaction will be different in different individuals.

Nevertheless, understanding the complexity of the caloric balance equation allows individuals to be more informed decision-makers in their health journey.

Read more about this topic in “Planet Fat”, a comprehensive book on why we get fat, why we should not feel guilty about it and what we can do about it. The book's central theme revolves around increasing awareness and knowledge to help people make informed choices suited to their unique circumstances.