What is the aim of nutrigenetics? Can it really help?

The aim of all dietary advice is to establish good eating habits permanently because good health in later life depends a great deal on how earlier life is lived.

Small changes, even apparently insignificant changes, can make a big difference over 10-20 years. For example the caloric excess per day required to gain 15 Kg from age 20 to age 40 is only 10 calories, which is just half a spoonful of sugar extra per day!