There are, however, some foods where the caloric expenditure to process them is a little higher than the calories they provide the system. The clear example is water, especially ice-cold water. The body needs to warm it up before absorbing it, leading to a small caloric debt. Foods with very high water content, such as celery, also have this tiny catabolic effect. But the nutritional value of water and celery are not high enough to properly sustain an organism, so relying solely on these foods to lose weight can lead to serious health complications.
Total RNA was isolated from cells by the TRIzol reagent (Thermo Fisher Scientific) according to manufacturer's instructions. The concentration of extracted RNA was determined using NanoDrop spectrophotometer. For miRNA RT reaction, 1 μg of total RNA was first converted into cDNA by Superscript III reverse transcriptase (Invitrogen), in which miRNA-specific stem-looped RT primers were used. RT reaction was done under the following condition: 16°C for 30 min, followed by 50 cycles of 20°C for 30 s, 42°C for 30 s and 50°C for 1 s. The enzyme was then inactivated at 70°C for 10 min. For mRNA, 1 μg of total RNA was used as templates to synthesize first-strand cDNA using oligo-dT primers. RT reaction was carried out at 42°C for 90 min and then 70°C for 15 min. For the quantitative determination of the reversely transcribed products, real-time PCR was performed on an Applied Biosystems 7500 Fast PCR System (Foster City, CA, USA) using the standard SYBR green method under the following condition: 95°C for 10 min, followed by 40 cycles of 95°C for 15 s and 60°C for 1 min. For expression analysis, the Ct values of mRNA targets and miRNA were first normalized respectively to those of the eukaryotic translation elongation factor 1 alpha 1 (EEF1A1) and U6 genes in the same samples. The resulting ∆Ct was further utilized to assess the relative gene expression between different experimental groups, with the data presented as fold change to control. Sequences of primers used in real-time PCR assay are listed in Table S1 .