While smoking causes a lot of health issues including predisposition to
diabetes, hypertension, and respiratory disorders including lung carcinoma, it has been linked to cause dyslipidemia. This in turn causes weight loss. Nonetheless there are much healthier ways to do so.
In contrast to what one might think when you quit nicotine, it causes weight gain which is much faster.
Next Steps
I would recommend you to consult a doctor if you're stressed and quit smoking as its easier now whilst you've just started. Its okay to have bad life decisions sometimes but don't let them overpower your will to do the right thing.