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Global Translational Medicine Mass balance

balance approach, and two separate articles by Arencibia- mass balance approach. Since these diligent researchers
Albite et al. and Manninen , respectively, have been have followed the EBT paradigm, “no adequate explanation
[12]
[7]
published on the subject; hence, it will not be discussed can be given for weight loss differences.” Young et al.
further in this present article. study has not received any substantial criticism. It is
worth noting that they utilized underwater weighing
9. Recent meta-analyses of randomized (i.e., hydrodensitometry) to determine body composition.
and controlled free-living feeding trials This method is more accurate than other widely available
supporting the mass balance approach methods of body composition testing. When performed
properly, underwater weighing may be accurate up to
Feeding trials performed on free-living subjects are always 1.8%–2.8% in comparison with the state-of-the-art
a mixture of effectiveness and compliance. When subjects methods (e.g., magnetic resonance imaging [MRI] and
are randomized to a certain diet, many are often not very computed tomography [CT]).
committed to following the prescribed diet. Usually, the
macronutrient distribution of the compared diets begins 11. Epidemiological data supporting the
to converge at the latest after 1 year. Nevertheless, a couple mass balance approach
of recent meta-analyses on the topic will be reviewed in
this paper. As recently pointed out by Mozaffarian [23] , the data
from the National Health and Nutrition Examination
In a meta-analysis by Choi et al. eight feeding trials Survey (NHANES) have shown no increase in energy
reporting changes in weight-related parameters were consumption or availability over ≥ 20 years, a time period
included in the study . The results indicated that very- during which obesity has steadily increased (see Figure 1
[20]
low-carbohydrate/high-fat diets were significantly more in Mozaffarian [23] ). In fact, the data from NHANES have
effective in reducing body mass than higher carbohydrate suggested a small but statistically significant decline in
control diets; these results are in accordance with the mass energy intake over this period [23] . What about the other
balance approach. As aforementioned, when the energy side of the coin, i.e., energy expenditure? Although there
fraction from dietary fat increases, while energy intake are no similar epidemiological data available on the
is fixed, mass intake decreases due to the significantly matter, high-quality studies utilizing the doubly labeled
higher energy density of fat compared with other energy water (DLW) method have indicated that the total
substrates.
energy expenditure (TEE) of Hadza hunter-gatherers
A recent meta-analysis by Zaki et al. has compared was similar to Westerners and other populations in
the effectiveness between very-low-carbohydrate diets market economies despite their high physical activity
and low-carbohydrate diets . In this comparison, the level [24] . Therefore, it is clear that the main factor causing
[21]
difference in nutrient mass intake was not as significant as the obesity epidemic is increased food intake rather than
in the aforementioned meta-analysis. As can be assumed declined expenditure.
based on the mass balance approach, those who were on If there has been no change in energy intake and
very-low-carbohydrate diets lost slightly more body mass energy consumption, what on earth is causing the obesity
than those on low-carbohydrate diets. There were some epidemic? If we follow the EBT paradigm, this seems
variations in the results, which must be attributed to poor paradoxical; however, from the perspective of the mass
compliance.
balance approach, there is nothing surprising about it.
10. An “old” well-controlled feeding According to nutritional recommendations, people should
experiment supporting the mass balance increase their intake of carbohydrates at the expense of
fat. If such recommendations are followed, the intake of
approach nutrient mass will increase, while the calorie intake remains
In the early seventies, Young et al. compared three diets that the same. The data from NHANES have indicated that
contained the same amount of calories (1,800 kcal/day) and the percentage of calories from carbohydrates increased
protein (115 g/day) but different carbohydrate contents . between 1971–1974 and 1999–2000 from 42.4% to 49.0%
[22]
After 9 weeks on the 30-g, 60-g, and 104-g carbohydrate for men and from 45.4% to 51.6% for women, whereas the
diet, the weight loss was 16.2 kg, 12.8 kg, and 11.9 kg, percentage of calories from fats decreased from 36.9% to
respectively, and fat accounted for 95%, 84%, and 75% 32.8% for men and from 36.1% to 32.8% for women .
[25]
of the weight loss. The authors thus concluded, “Weight Although self-reported dietary intake is subjected to recall
loss, fat loss, and percent of weight loss as fat appeared bias, there is every reason to assume that strongly marketed
to be inversely related to the level of carbohydrate in the nutritional recommendations have produced results in line
isocaloric, isoprotein diets.” This is consistent with the with the goals at the population level.

Volume 2 Issue 1 (2023) 8 https://doi.org/10.36922/gtm.222