Monitoring your weight on a regular basis can become frustrating, just step on the scale two days in a row to observe even surprising variations, sometimes in the order of one or two kilogramsThis happens especially after a larger meal, a trip, or a change in your workout routine. However, Not all weight changes are indicative of a real change in body composition.Understanding what lies behind these fluctuations is essential, especially for those who play sports or follow a structured nutritional plan.
The glycogen factor
One of the main factors that contributes to rapid weight fluctuations is muscle and liver glycogenGlycogen is the storage form of carbohydrates in our body and has a well-documented characteristic in literature: for every gram of glycogen stored, about three or four grams of water are retained.
This means that, following a period of carbohydrate loading, body weight can increase rapidly without any increase in fat mass. On the contrary, after prolonged or particularly intense training sessions, glycogen reserves are reduced and with them also the associated water, determining a weight loss that can be observed already in the following hours.
It is important to underline that the ability to store glycogen is highly subjective and depends on factors such as muscle mass, training level and usual diet, making it impossible to quantify with a universal value the change in weight for glycogen that is valid for everyone.
The water balance
Next to glycogen, another key element is water balanceDehydration, even mild, can cause an acute reduction in body weight after physical activity. However, in the following days, the body tends to compensate by retaining fluids, especially if sodium intake is high or if rehydration is inadequate. This mechanism is regulated by hormones such as aldosterone and vasopressin, which modulate the reabsorption of water and sodium at the renal level. Consequently, a phase of dehydration can paradoxically be followed by a temporary weight gain, linked to water retention.
This phenomenon becomes even more evident after particularly rich meals, such as a pizza or a sushi meal with soy sauce, therefore with a high sodium content. The increased salt intake induces greater fluid retention, with an increase in weight that can manifest itself in the following days. Added to this is the fact that large meals, rich in carbohydrates and bulky, also lead to an increase in intestinal content: the weight of the food mass not yet digested and absorbed further contributes to the variation observed on the scale, until the digestive process is complete.
The most intense workouts
Sometimes it can happen that weigh more after an intense workoutIn this case, it is the microtraumas of the muscle fibers that activate repair processes and lead to a temporary increase in capillary permeability, attracting fluids into the tissues.
This can translate into a slight local water retention and an increase in body weight in the days following training, generally limited and transient, with a duration varying from 24 to 72 hours depending on the intensity of the effort and the level of training.
Lifestyle and sleep deprivation
Even factors seemingly unrelated to diet and exercise can influence body weight. Prolonged sedentary behavior, such as during a flight or a workday spent sitting or standing without moving, can promote fluid retention, especially in the lower limbs.
This is related to a reduction in venous and lymphatic return, accentuated in hot conditionsThe result is a feeling of bloating and a temporary weight gain, which tends to resolve within a night or a day with the restoration of movement and normal hydration. To counteract this retention, simple strategies such as walking, changing positions, raising your legs and maintaining good hydration throughout the day.
In weight variations, sleep deprivation plays a sinister roleScientific studies have shown that sleep deprivation alters the release of vasopressin, which affects the regulation of water balance. When we sleep less than six hours, the body tends to retain more fluids, increasing swelling and water retention in the hours that follow.
The menstrual cycle
Finally, it is essential to consider the variations related to the menstrual cycle in womenHormonal fluctuations, particularly estrogen and progesterone, influence fluid balance and sodium regulation.
In the luteal phase (the second half of the menstrual cycle, ed.) and in the days preceding menstruation, it is common to observe an increase in water retention, with weight variations that can reach one or two kilograms. These are also temporary changes that tend to resolve spontaneously with the onset of menstrual flow.
When to weigh yourself?
In light of these considerations, it appears evident that body weight is a dynamic parameter, influenced by numerous factors and often independent of fat massa. For this reason, the interpretation of weight changes always requires careful evaluation.
Observe trends in the medium-long term and step on the scale once a week at most, avoiding days when we know that our weight can be altered by other factors, represents a more reliable approach and consistent with scientific evidence, rather than dwelling on daily fluctuations.
