Immediately after the zombie apocalypse, it won't be just the prepared who will be the survivors, random people will also be survivors. It would not be a rash bet to say that these people will outnumber the prepared. Knowing that state of the general health and fitness of average people nowadays, will these people survive? Will they have no chance at all?
Being overweight not only has the obvious problem of size but breathing difficulties, low fitness levels, diabetes.
Heavy smokers will also have little fitness not to mention suffering withdrawal symptoms.
How many of these people who survive the initial outbreak will even last a week (Not even bringing into the question of fighting off zombies/living rough.)?
I would say that looking after yourself now is far more important than
buying guns and ammo.
More importantly, how are you preparing your body for the ultimate game of survival of the fittest?