If I may, you need to improve the clarity of your writing.

Don't know how many people feel despair(ed) when they see the figure of himself themselves in (the) mirror, perhaps in that moment they all may regret one thing, which (that is) responsible for gaining weight too quick is  (:) eating too much and too frequent(ly). (H)however, in my opinion, people shouldn't just blame himself lack of (themselves for lacking) self-discipline, (and) some of experts (who) provide misleading information also should take the responsibility (be held accountable).

Health expert(s) often advise people need (to eat) meals 3 times per day, otherwise your body may be in danger, but they forget one thing that (a) human's body just (is) like a machine (that) only can (only) handle certain level of fuel, any attempting  of over filling  (to overfill) could cause engine failure(s), (and) that is why people have various heart disease(s), diabetes and other diseases.

A recent news reported, (delete comma) (that) a female worker who got buried over 17 days without food was still fine except felt (feeling) weak. (W)what this story tells us is human's digest system is much stronger than we thought and we should give our body (bodies) a chance to dig (tap into) the potential for the purpose of cleaning up the internal systems.