Decreased muscle mass is a constant in overweight or obese people, due to low-quality diets that lack fruits and vegetables, whole grains and legumes and contain excessive amounts of added sugar and saturated fatty acids, compared to unsaturated fatty acids. Profile that is conducive to the development of weight gain and chronic non-communicable diseases (NCDs). Thus, in this context we have studies that suggest diets with calorie restriction and rich in proteins, as capable of weight loss and at the same time improve the dietary profile, reduce the loss of lean mass and emergence of NCDs.
Given this, data from the literature show that weight loss between 5% and 10% can prevent chronic diseases, and when this is associated with a higher protein intake it has been extensively linked to a healthy body weight, as well as the benefits already listed earlier. In addition, it has been shown that dietary protein contributes to nutrient adequacy in the general population.
On the other hand, evidence shows that a better quality diet it has health benefits and that is associated with less weight gain, or greater weight loss. That is, there is a greater incentive for the intake of fruits, vegetables, whole grains and protein foods rich in fiber and unsaturated fats. As well, it discourages the intake of saturated fatty acids, refined grains, added sugar and sodium.
With this, the study discussed here sought to research whether a higher protein intake during weight loss and a better quality of diet would be associated with an attenuation of lean mass loss compared to a lower protein intake. Therefore, 207 overweight or obese adults were examined before and during 6 months of calorie restriction with approximately 10 dietary records per person. In which, the quality of the diet was evaluated by means of the Healthy Eating Index in 2 groups: lower (LP) and higher (HP) protein intake.
Protein, Calorie Restriction and Diet
A higher quality diet is associated with weight loss, in large part this can be explained by higher intake of fiber, fruits and vegetables and controlled portion sizes. Consistent with this data, the results of the study in question showed an improvement in diet quality during calorie restriction (CR) compared to baseline. In addition, a higher protein intake during calorie restriction has been shown to contribute to health-related benefits, which can be attributed to a higher protein intake, as well as to the change in eating patterns caused by the change in protein intake.
Overall, the results found show that individuals who had a higher protein intake (79 g/d), compared to lower protein intake (58 g/d), during calorie restriction had a greater improvement in diet quality.. Moreover, in addition to the change in protein intake in the HP group compared to the LP group, it resulted not only in higher total protein and dairy scores, but also higher intake of dark green vegetables and reduced intake of refined grains and added sugar.
Dietary Protein Distribution and Muscle Mass
Another important finding is that individuals who had a higher protein intake during CR lost less muscle mass. than those who consumed lower protein intake. In other words, the LP and HP groups consumed 58 and 79 g/d of protein, and had a muscle mass change of -1.0 and -0.6 kg, respectively. Therefore, when 2 levels of protein intake were examined, a trend towards greater loss of lean body mass was observed in the LP group.
In line with these data, in a study of older adults, self-selected protein intake was examined over 3 years in 2,066 individuals who were not undergoing a weight loss process. In this study, the levels of protein consumed were 55 g/d compared to 79 g/d, and the change in lean body mass was -0.9 kg and -0.5 kg in the 2 groups, respectively.
Briefly, the researchers of the study discussed here suggest that a higher dietary protein of about 80 g/d (or 1 g/kg/d) preserves muscle mass compared to a normal protein intake of ~60 g/d (or 0.8 g/kg/d). This may be especially important to consider in women and elderly populations who are more likely to consume inadequate dietary proteins.
Protein Quality and Muscle Mass
Data show that during the reduction of energy intake, lean protein sources, especially birds, were responsible for a significant proportion of the variation in the alteration of body muscle mass during the weight loss process.
In addition, a higher intake of protein from lean animal and plant sources, with dietary advice to support weight loss, may contribute to a healthier eating pattern, as indicated by a lower consumption of refined grains and added sugar and a higher consumption of green vegetables. It is worth mentioning that in both groups of protein HP and LP the intake of saturated fatty acids was 23 g/d at the beginning and decreased to 17 g/d in both groups of protein during caloric restriction.
In conclusion, the data found show that a moderately higher intake of protein during CR improves diet quality and attenuates lean mass loss.. In addition, the quality of the diet was improved due to the consumption of low-fat protein sources, higher intake of green vegetables and reduced intake of refined grains.
Clinical practice
Clinically, moderately higher protein intake (1.0 g/kg/d) at 20% of energy intake can be encouraged for successful weight loss, to improve diet quality, and to mitigate loss of lean body mass.
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