Proportions may be the key….
In a recent study, researchers analyzed data from 38 trials where participants had kept a food diary for 2+ days and the macronutrient portion of their diets were manipulated. Analysis of percent protein in diet versus total energy intake showed that when a person’s diet was decreased from 20% protein to 10% protein, there was a significant increase in non-protein energy consumption and vice versa. Comparison of the log non-protein intake decreased compared to percentage of dietary protein intake (t= -13.1, p<0.0001). Age, study duration and baseline BMI had no impact on dietary percent protein versus non-protein energy intake, but sex, however, did. Men tended to have a higher dietary protein intake as compared to women (t = −5.3, P < 0.0001 female vs. male dietary protein intake). The study also analyzed high protein intake but diets with >20% protein did not show significant correlation to decline in energy consumption. In fact, after dietary protein amounts increased >20.9%, the percent protein intake vs. total energy intake difference was negligible.
According to the authors, maintaining proper proportions of macronutrients is not only important not only for our muscles and cellular building blocks but also to keep overall non-protein (carbohydrate and fat) energy intake down. The authors also noted that the study did not show any great benefit to high protein diets (>20%) which can come with other problems such as kidney failure and/or high cholesterol depending on the protein source.
- Persons who maintain diets with 15-20% protein intake tend to intake less energy from carbohydrates and fats.
- Macronutrient energy intake should be calculated as a percentage of total diet; actual protein amount (i.e. grams) doesn’t matter as much if it is diluted by the amount of carbohydrates and fats.
- Persons who fall in low socioeconomic status and women tend to eat less protein.
Gosby, A. et al. Protein leverage and energy intake. Obesity Reviews (2013)