I get the sense that you are trying too much all at once.
1. Do not try to quit smoking + drastically change your diet at
the same time. Focus on your diet first while cutting down on your
cigarette smoking gradually.
If you can do both successfully, then you have my respect.
Otherwise, focus on one challenge head-on, and tackle the other
challenge gradually.
2. Do not skip any meals, be it breakfast, lunch, or dinner.
Otherwise, as others have pointed out, if you skimp on the earlier
meals, you tend to overcompensate for dinner (which is all the more
worse since your metabolism is at its lowest then).
Think about it.... what you ate for dinner is more than what I
ate for the whole day!
3. Healthy eating does not mean you must turn vegan overnight or
must give up all red meat. It's all about making healthier choices,
such as braised chicken instead of fried chicken, fish instead of
pork, or asking the chai png auntie for more veggies.
4. If you tend to snack, buy those little packets of California
raisins or cranberries. Snacking on fruit is far more preferable to
snacking on chocolates and other junk.
