Effective means of managing weight include:

 Eh some of these things are objective and may vary between authorities, such as using food as a reward. Controlling portions/ consuming less calories is certainly one of the answers. Fad diets aren't effective long term so that's probably not an answer. Limiting snacks depends on the person and their schedule, as long as calories are kept reasonable and from healthy sources snacks are fine.

Inaccuracy is a disadvantage