If foods defrost on the way Home and you re-freeze them in a domestic freezer, large ice crystals will form and can rupture cell membranes in the food allowing nutrients to escape.

But unlike the laser treatments, which exploit biochemical pathways to create pores in the fat cell, they generate mechanical forces that rupture these cells.

When cells and viruses are cooled, their membranes often change suddenly - similar to the way water molecules reorganize during freezing - and this can rupture the membrane and kill the cell.