As we have commented in previous posts, body weight is one of the most important factors in performance in endurance sports. A lower body weight will allow us to be more efficient and also reduce stress on our joints. That is why, now that the competitive period is approaching in sports such as triathlon, it is essential to achieve that optimum weight.
Proteins play an important role in body weight. In fact, numerous studies have shown that diets high in protein (1.2-1.6 g / kg / day in the general population and up to 2 g / kg / day in athletes) are more effective for weight loss than those with low content in this macronutrient .
In periods of caloric restriction (that is, when we eat less than we spend) there is a loss of muscle mass, which can have serious consequences for performance. In addition, there is a decrease in our metabolic expenditure, making it increasingly difficult for us to lose weight. It has been observed that diets high in protein could attenuate this decrease in metabolic expenditure by preserving muscle mass . The proteins also have a greater satiating effect than fats or carbohydrates, thus facilitating the caloric deficit. For example, one study  compared the effects of a breakfast with high (35 g of protein) or low (13 g) protein content for 12 weeks. The results showed that the high protein breakfast avoided the gains in fat mass that were observed in the group that consumed a breakfast low in protein. In addition, those who ate more protein breakfast decreased their caloric intake during the day.
Therefore, proteins should play a major role in our diet if we are athletes, but especially if our goal is to keep weight. An optimal intake of this macronutrient (e.g. 25-30 g / meal) will allow us to satisfy our appetite and avoid the loss of muscle mass that accompanies periods of caloric restriction. But can we take an excess of proteins without worrying about gaining body weight? To answer this question, a study published in JAMA  analyzed people who consumed more than they spent for 8 weeks, but some consuming a low-protein diet (5% of total energy), others with a medium content (15%) and others with a high content (25%). The results showed that the group that got that excess of calories through a lower consumption of proteins gained less body weight than the other groups. However, the fat gain was the same in the three groups, the differences in weight being caused by a greater increase in muscle mass (together with a higher metabolic expenditure) in the groups that consumed more protein. In summary, an excessive consumption of
proteins over our energy expenditure can also result in an increase in body weight and fat mass, although normally in these situations the body weight increases due to the greater muscle mass.
1. Leidy HJ, Clifton PM, Astrup A, Wycherley TP, Westerterp-plantenga MS, Luscombe-marsh ND, et al. The role of protein in weight loss and maintenance. Am. J. Clin. Nutr. 2015;101:1320–9.
2. Leidy HJ, Hoertel HA, Douglas SM, Higgins KA, Shafer RS. A high-protein breakfast prevents body fat gain, through reductions in daily intake and hunger, in “breakfast skipping” adolescents. Obesity. 2015;23:1761–4.
3. Bray GA, Smith SR, Rood J, Martin CK, Most M, Brock C, et al. Effect of Dietary Protein Content on Weight Gain, Energy Expenditure, and Body Composition During Overeating. JAMA. 2012;307:47–55.