The present invention provides a method and a dietary composition for prevention and regulation of obesity capable of obtaining efficacy such as required appetite suppression or satiety by having a positive effect on concentrations of neurotransmitters such as serotonin, dopamine, and norepinephrine, and GLP-1 which are the principle of a mechanism of appetite inhibitory drugs without prescription of medicines (Phentermine, Prozac, Saxenda, etc.) and further being used as an alternative diet and supplying a protein that is the most lack ingredient during diet. The dietary composition includes tryptophan, which is one amino acid, tyrosine, which is the other amino acid, arginine, which is another amino acid, and a whey protein as active ingredients.