Use of an agent which comprises, as an active ingredient, an amino acids mixture, wherein the ratio of the amino acids is from 2 to 15 moles threonine, from 4 to 30 moles of proline, from 7 to 20 moles of glycine, from 4 to 8 moles of valine, from 3 to 9 moles of isoleucine, from 2 to 12 moles of leucine, from 1 to 9 moles of tyrosine, from 0.5 to 5 moles of phenylalanine, from 5 to 11 moles oflysine, from 0.1 to 5 moles of aspartic acid, from 0.1 to 5 moles of serine, from 0.1 to 4 moles of glutamic acid, from 0.1 to 12 moles of alanine, from 0.1 to 5 moles of methionine, from 0.1 to 5 moles of histidine and from 0.1 to 5 moles of arginine, in the manufacture of a composition for prevention of obesity by increasing body temperature.
