When starting a plan with the goal of fat loss, it can be common that there is a large initial weight loss, which causes the person to be motivated and believe that they are losing a lot of fat in such a short time.
This loss can vary from individual to individual, reaching from a measly 1 to 2 kg to an incredible 10 kg or more, in a matter of days or weeks. But what is really going on with this weight loss? Is this all fat? And, of course, the answer is no!
When you lose weight, you can lose not only fat, but mainly water and other fat-free components, such as intramuscular glycogen (the way your body stores the carbohydrates ingested from the diet) and even protein (which makes up your muscle mass). .
Fat loss, on the other hand, boils down to the actual use of calories stored in your adipose tissue (in the form of triacylglycerol) as energy, with no reward for this storage. Here, yes, we have the real loss of body fat and this can only be achieved through a caloric deficit imposed for a medium/long term (ingesting fewer calories than expended).
Returning to weight loss, in view of the extra and intracellular retention capacity of our body, here is the main responsible for weight loss, water, followed by muscle glycogen.
Simply put, we have the capacity to store about 600 grams of glycogen in our body, mainly in the muscles, but also in the liver, brain, heart, erythrocytes, etc. Each gram of glycogen attracts about 3 to 4 grams of water, plus potassium. Doing a quick math, 500 grams of muscle glycogen can generate a total weight of 2.5 kg. This is all part of intracellular retention.
On the other hand, extracellular retention, the one we see between the skin and the muscle, occurs due to the presence of sodium (something normal) and tends to occur more sharply in sedentary people and people with poor diet, due, among other things, to a greater insulin resistance, leading to greater sodium reabsorption in the kidneys and, consequently, increasing extracellular water retention.
Once a person has engaged in a fitness routine at the gym, aerobics and has also followed a lower calorie diet, mostly restricted in carbohydrates, their weight will tend to drop. The greater initial loss will then be due to loss of extracellular retention (through improved insulin sensitivity), in addition to less muscle glycogen formation and, consequently, intracellular water loss.
Fat loss will only occur in the long term. According to the static model, to lose one kilo of fat it is necessary to burn about 7700kcal. Considering a daily caloric deficit of 500kcal, it would take about 15 days to lose one kilo of body fat. However, with physiological adaptations, this fat loss is not linear and tends to decrease over time, requiring a greater caloric deficit to continue losing the same amount of body fat.
In this way, it is possible to understand how it takes time to really lose body fat. The secret, then, is the combination of proper diet, physical activity and, above all, consistency!
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References:
Kreitzman SN, Coxon AY, Szaz KF. Glycogen storage: illusions of easy weight loss, excessive weight regain, and distortions in estimates of body composition. Am J Clin Nutr. 1992 Jul;56(1 Suppl):292S-293S. doi: 10.1093/ajcn/56.1.292S. PMID: 1615908.
Murray B, Rosenbloom C. Fundamentals of glycogen metabolism for coaches and athletes. Nutr Rev. 2018 Apr 1;76(4):243-259. doi: 10.1093/nutrit/nuy001. PMID: 29444266; PMCID: PMC6019055.
Rocchini AP, Katch V, Kveselis D, Moorehead C, Martin M, Lampman R, Gregory M. Insulin and renal sodium retention in obese adolescents. Hypertension. 1989 Oct;14(4):367-74. doi: 10.1161/01.hyp.14.4.367. PMID: 2676858.
Trexler, E.T., Smith-Ryan, A.E. & Norton, L.E. Metabolic adaptation to weight loss: implications for the athlete. J Int Soc Sports Nutr 11, 7 (2014). https://doi.org/10.1186/1550-2783-11-7
This loss can vary from individual to individual, reaching from a measly 1 to 2 kg to an incredible 10 kg or more, in a matter of days or weeks. But what is really going on with this weight loss? Is this all fat? And, of course, the answer is no!
When you lose weight, you can lose not only fat, but mainly water and other fat-free components, such as intramuscular glycogen (the way your body stores the carbohydrates ingested from the diet) and even protein (which makes up your muscle mass). .
Fat loss, on the other hand, boils down to the actual use of calories stored in your adipose tissue (in the form of triacylglycerol) as energy, with no reward for this storage. Here, yes, we have the real loss of body fat and this can only be achieved through a caloric deficit imposed for a medium/long term (ingesting fewer calories than expended).
Returning to weight loss, in view of the extra and intracellular retention capacity of our body, here is the main responsible for weight loss, water, followed by muscle glycogen.
Simply put, we have the capacity to store about 600 grams of glycogen in our body, mainly in the muscles, but also in the liver, brain, heart, erythrocytes, etc. Each gram of glycogen attracts about 3 to 4 grams of water, plus potassium. Doing a quick math, 500 grams of muscle glycogen can generate a total weight of 2.5 kg. This is all part of intracellular retention.
On the other hand, extracellular retention, the one we see between the skin and the muscle, occurs due to the presence of sodium (something normal) and tends to occur more sharply in sedentary people and people with poor diet, due, among other things, to a greater insulin resistance, leading to greater sodium reabsorption in the kidneys and, consequently, increasing extracellular water retention.
Once a person has engaged in a fitness routine at the gym, aerobics and has also followed a lower calorie diet, mostly restricted in carbohydrates, their weight will tend to drop. The greater initial loss will then be due to loss of extracellular retention (through improved insulin sensitivity), in addition to less muscle glycogen formation and, consequently, intracellular water loss.
Fat loss will only occur in the long term. According to the static model, to lose one kilo of fat it is necessary to burn about 7700kcal. Considering a daily caloric deficit of 500kcal, it would take about 15 days to lose one kilo of body fat. However, with physiological adaptations, this fat loss is not linear and tends to decrease over time, requiring a greater caloric deficit to continue losing the same amount of body fat.
In this way, it is possible to understand how it takes time to really lose body fat. The secret, then, is the combination of proper diet, physical activity and, above all, consistency!
--
References:
Kreitzman SN, Coxon AY, Szaz KF. Glycogen storage: illusions of easy weight loss, excessive weight regain, and distortions in estimates of body composition. Am J Clin Nutr. 1992 Jul;56(1 Suppl):292S-293S. doi: 10.1093/ajcn/56.1.292S. PMID: 1615908.
Murray B, Rosenbloom C. Fundamentals of glycogen metabolism for coaches and athletes. Nutr Rev. 2018 Apr 1;76(4):243-259. doi: 10.1093/nutrit/nuy001. PMID: 29444266; PMCID: PMC6019055.
Rocchini AP, Katch V, Kveselis D, Moorehead C, Martin M, Lampman R, Gregory M. Insulin and renal sodium retention in obese adolescents. Hypertension. 1989 Oct;14(4):367-74. doi: 10.1161/01.hyp.14.4.367. PMID: 2676858.
Trexler, E.T., Smith-Ryan, A.E. & Norton, L.E. Metabolic adaptation to weight loss: implications for the athlete. J Int Soc Sports Nutr 11, 7 (2014). https://doi.org/10.1186/1550-2783-11-7
