As many of you know, having seen me grow up at SPORTFORMA—where I still spend much of my time as a volunteer when I am not at university—I am a Pharmacy student.
Recently, I spent a lot of time studying for my Nutritional Physiology exam, one of the university subjects that rigorously explores the mechanisms regulating diet, metabolism, and the body's adaptation to physical activity.
And that is precisely where this reflection stems from.
Between studying and daily life at the gym, I realized how often—especially in fitness—oversimplified, repeated, and sometimes inaccurate information circulates. At the same time, I rediscovered how fascinating it is to truly understand what happens "behind the scenes" of our body: knowledge that anyone practicing sports, or simply taking care of their health, should have access to in a clear, reliable, and understandable way.
This is why I decided to launch a series of articles dedicated to nutrition, aiming to share what I am studying in a simple, practical way that can be applied to the athletic life of all SPORTFORMA members and friends.
To kick things off, I couldn't help but start with one of the most common questions among those who train…
To understand how weight loss works (or how to build lean muscle mass), nutritional science teaches us that everything revolves around one key concept: energy balance. For body weight to remain stable, energy intake (the calories we eat) must equal energy expenditure (the calories we burn).
But what makes up this "energy expenditure"? Physiology shows us that our caloric output is divided into three distinct categories.
Basal Metabolic Rate (The engine that never stops)
The most surprising discovery is that we burn the vast majority of our calories doing... absolutely nothing! Basal Metabolic Rate (BMR) is the amount of energy expended by the body at complete rest while fasting. It keeps us alive by sustaining vital systems and cellular functions: heart activity, breathing, kidney function, liver metabolism, and baseline muscle tone. This quiet engine accounts for 60-75% of our total daily energy expenditure and depends on factors like sex, age, height, and body weight.
Diet-Induced Thermogenesis (DIT)
That's right, eating burns calories! Diet-Induced Thermogenesis (DIT) is the energy our gastrointestinal tract expends to digest, absorb, and metabolize nutrients we consume. This internal processing consumes between 10% and 15% of our daily calories.
Physical Activity (The variable under our control)
Finally, we come to the energy spent moving, walking, and training here at SPORTFORMA. In an average sedentary adult, physical activity represents about 15-30% of total caloric output, but in active athletes, it can reach 3 to 4 times the basal metabolic rate. It is the only component over which we have direct, immediate control to tilt the balance in our favor.
The strict rule of "Fat Reserves"
Our body is a machine designed for survival. If energy intake (food) exceeds energy expenditure (BMR + DIT + Physical Activity), the balance becomes positive: excess energy doesn't disappear; it is converted into fat and stored in the body as reserves, causing weight gain. Conversely, when we create a caloric deficit (eating a balanced diet and exercising regularly), the body is forced to tap into those fat reserves, resulting in weight loss.
I hope this information gives you the right motivation to take on your next workout with a fresh perspective.
See you soon at SPORTFORMA to put all of this into practice together! In the next article, we will answer the question: "Why do we feel hungry or full?" We will discuss the hunger hormones: Ghrelin vs. Leptin, and discover how they trick our brain!
Until next time!
- Gloria Carli — articoli
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Gloria Carli
Gloria Carli è studentessa presso la Facoltà di Farmacia dell’Università di Torino.
Fa parte del Consiglio Direttivo della Sportforma APS, dove, in qualità di volontaria, è impegnata nell’organizzazione, progettazione e coordinamento delle attività.
