## 4 Effects of Obesity on Micronutrient Deficiency  
The evidence clearly showing the development of micronutrient deficiencies with the progression of obesity comes from animal studies. For example, [PERSON] et al. (2015) found impaired vitamin A transcriptional signaling in murine organs, which advanced with increasing adiposity and fatty liver but normalized with weight loss ([PERSON] et al., 2016), while [PERSON] et al. (2016) showed that Fe storage in murine livers was lowered due to obesity but could be restored by the administration of a low-fat diet ([PERSON] et al., 2016). Prospective studies on the development of micronutrient malnutrition in humans with the advancement of excessive weight gain are lacking; however, many works show that weight loss may affect blood levels of vitamins and minerals. Broadly researched in this respect is vitamin D. A meta-analysis of RCTs and controlled trials without randomization reported that serum 25-hydroxyvitamin D increased with weight reduction by a modest mean difference (MD) of 1.24 ng/mL and 1.94 ng/mL in each group of studies, respectively, with no dose-dependent effects for weight loss ([PERSON] et al., 2016). The status of other nutrients during the treatment of obesity was also looked at. An overview of the results from exemplary trials is gathered in Table 2.  
With weight loss, blood levels of vitamins A, E, C, and B1 were found to decrease ([PERSON] et al., 2016; [PERSON] et al., 2016; [PERSON] et al., 2016), while no appreciable changes in Se and Ca were noted ([PERSON] et al., 2016; [PERSON] et al., 2016). On the other hand, the status of Mg, Fe, and Zn, as well as vitamins B6, B9, and B12, was shown to improve ([PERSON] et al., 2016; [PERSON] et al., 2016; [PERSON] et al., 2016; [PERSON] et al., 2016). The impact of dietary interventions that caused weight loss on the micronutrient status of patients participating in studies listed in Table 2 cannot be ignored since these \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Micronutrient**} & **Mean or Median \% Change within Group** & \multirow{2}{*}{**Studied Group**} & **Mean or Median Weight Loss within Group (kg)** & **Treatment Duration** & **Reference** \\ \hline Serum vit. A & \(-\)22 & Danish \(\hat{}\) adults with & & & \\ \hline Serum vit. E & \(-\)25 & obesity & 12 & 8 weeks & [28] \\ Plasma vit. C & \(-\)27 & American \(\hat{}\) adults with & & & \\  & & obesity & & & \\ \hline Erythrocyte vit. B1 & \(-\)12 & \begin{tabular}{c} Australian \(\hat{}\) adults with \\ T2D 1 and regular levels of \\ vit. B1 in the diet \\ \end{tabular} & 10 & 16 weeks & [30] \\ \hline \hline Plasma vit. B6 & 52 & \begin{tabular}{c} Spanish \(\hat{}\) women with \\ obesity on hypocaloric \\ cereal-based diet \\ \end{tabular} & 3 & 6 weeks & [31] \\ \hline Serum vit. B9 & 217 & Danish \(\hat{}\) adults with & & & \\ \hline Serum vit. B12 & 24 & obesity & 12 & 8 weeks & [28] \\ \hline Serum Mg & 5 & \begin{tabular}{c} Norwegian \(\hat{}\) patients with \\ a BMI in the obese range \\ \end{tabular} & 10 & 8 weeks & [32] \\ \hline Serum Ca & \(<\)\(-\)1 & \begin{tabular}{c} Jordanian \(\hat{}\) women with \\ obesity \\ \end{tabular} & 10 & 3 months & [33] \\ \hline Serum Fe & 35 & \
\begin{tabular}{c} Jordanian \(\hat{}\) women (18–30 \\ years old) \\ \end{tabular} & 7 & 3 months & [34] \\ \hline Serum Se & \(<\)\(-\)1 & Cypriot \(\hat{}\) adults & 1 & 8 weeks & [35] \\ \hline Serum Zn & 10 &
\begin{tabular}{c} Egyptian \(\hat{}\) students on \\ low-carbohydrate diet \\ \end{tabular} & 6 & 40 days & [36] \\ \hline \hline \end{tabular}  
* Type 2 diabetes, \(\hat{}\) denotes patients eligible to participate in the study carried out in this country. Color coding means that there was (dark-grey for decrease and white for increase) or there was not (light-grey) a significant change in the status of the particular nutrient. Data that were sourced out from the studies on the effects of micronutrient supplementation are results for control groups where no supplementation was used.  
\end{table}