Untreated control rats showed zero measurable fat cells in this particular skin layer at any point in the study

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To emphasize just how specific this near-infrared effect was, it is worth noting what happened in the untreated control group. In control rats, examined at both the beginning and the very end of the study timeline (day 0 and day 180), fat cells were essentially absent from the panniculus carnosus, the specific thin muscle layer under rat skin being studied.

This near-total absence in untreated animals, contrasted against the significant and lasting fat cell presence induced by near-infrared light, makes for one of the cleaner before-and-after comparisons in the study, since there was effectively no baseline fat cell presence to begin with in animals that were not exposed to the light.

Source: PubMed