They can. For example, spicy food puts strain on your digestion system, and this makes you uncomfortable and even without knowing, your body and brain become stressed. Unhealthy food causes sleeplessness and this can lead to stress. Alcohol consumption can also lead to stress and so does smoking. Aerated drinks and junk foods can give you sudden sugar spikes and this can lead to stress. Hence, if you have been indulging in these activities, you should urgently go for a stress test.