**2. Background**

After a thorough bibliographic query including the terms "Metabolomics" or "Metabonomics" and "Mass Spectrometry" or "Nuclear Magnetic Resonance" and "Anorexia Nervosa", we found 72 records. Only studies that performed metabolomics (either targeted or untargeted, by NMR or MS) of human samples of AN patients from the last 10 years were included. Thirteen studies were therefore selected for the narrative review and they are summarized in Table 1.

Four studies out of thirteen employed a targeted metabolomics approach: only [47–50]. Other studies used a combined targeted and untargeted metabolomics approach in their analyses [51–54]. Most of the studies included used MS for the instrumental analysis. Prochazkova et al. used a combination of NMR and MS for metabolite identification and quantification [54]. Salehi et al. performed serum profiling of AN samples by 1H NMR [55].

All the included studies were performed on young adult human females. All the studies performed, with the exception of one, were based on case vs. control analyses, comparing a healthy control group to AN patients. However, ten of them also included patients after treatment, either in the short-term, the long-term, or fully recovered patients [47–49,52–58]. Bulant et al. studied the evolution of the steroid profile of hospitalized women with anorexia nervosa with no control group [50]. One study also performed a timeline analysis including fasting and postprandial samples [56]. Four studies specified that the patients had the restricting type of AN [47,48,51,54]. Moreover, two studies included AN-R and AN-BP patients and established comparisons between them and the healthy controls [37,49]. Three more studies identified both types of AN in their patients, but they did not perform any differential analysis between them [57,58].

Regarding the type of sample analyzed, plasma/serum samples were selected in nine studies [47–53,55,56], and fecal samples from AN patients were analyzed in the rest of the investigations [37,54,57,58].

**Table 1.**

Metabolomics

 studies on AN in human.

**Table 1.** *Cont.*

**Table 1.** *Cont.*