PROTEIN CONSUMPTION AND CHANGES IN BODY WEIGHT
As we have discussed in previous posts, body weight is one of the most important factors in endurance sports performance. 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 in sports such as triathlon is approaching, it is important to reach an appropriate performance weight.
Protein plays 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 a low content of this macronutrient [1].
In periods of caloric restriction (i.e. 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 high-protein diets could attenuate that decrease in metabolic expenditure by preserving muscle mass [1]. Proteins also have a greater satiating effect than fats or carbohydrates, thus facilitating caloric deficits. For example, one study [2] compared, over 12 weeks, the effects of a breakfast with high (35 g protein) or low (13 g) protein content. The results showed that the high-protein breakfast avoided the gains in fat mass that were seen in the low-protein breakfast group. In addition, those who ate more protein for breakfast decreased their calorie intake during the day.
Therefore, protein should play a major role in our diet if we are athletes, but especially if our goal is to manage body weight. An optimal intake of this macronutrient (e.g. 25-30 g/meal) will allow us to satiate our appetite and avoid the loss of muscle mass that accompanies periods of caloric restriction. But can we consume excess protein without worrying about gaining body weight?
To answer this question, a study published in JAMA [3] looked at people who consumed more than they spent for 8 weeks, but some ate a low-protein diet (5% of total energy), others had a medium protein diet (15%), and a high-protein diet (25%). The results showed that the group that got that excess calories through lower protein intake gained less body weight than the other groups. However, fat gain was the same in all three groups, with differences in weight being caused by a greater increase in muscle mass (along with higher metabolic expenditure) in the groups that consumed more protein. In summary, an excessive consumption of protein above our energy expenditure can also result in an increase in body weight and fat mass, although normally in these situations part of the increase in body weight is due to greater muscle mass.
References
- 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.
- 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.
- 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.
AUTHOR
Pedro Valenzuela
Researcher in the Physiology Unit of the University of Alcalá and in the Performance Control Unit at the Sports Medicine Center (AEPSAD, CAR of Madrid).
Web: www.fissac.com
