What effect does bad food really have?

So, I've been back on track with my eating the past week and I'm starting to feel so much better all around.  It made me start to think about how food really affects your body.  Of course we all know that we should eat healthy foods that provide our body with necessary nutrients, but does it physically change our bodies that quickly or is it just mental?  The first week I went off the wagon and ate crappy foods I felt okay, but definitely not good.  I felt fat and gross, but that was to be expected along with the fun bloating due to overabundance of food I was eating.  I have always been hard on myself so I chalked it up to poor choices and my mind taking over and making me feel bad for being so dumb and eliminating all of my hard work I put in getting into good shape.  That didn't stop me though and I continued with the nachos, mexican food, burgers, and everything else I could get my fat little hands on.  But what happened sort of surprised me...I would sporadically get waves of nausea during the second week.  It wasn't too bad, but I've never been one to throw up, even through 2 pregnancies with absolutely no morning sickness.  Hmmm am I on to something here?  Nothing else had changed: work, kids, school, and life in general were all the same.  I told myself it was nothing  and apparently a little bit of nausea can't keep my inner fat girl away.  So I continued with my horrendous eating and then I started having headaches and I didn't want to do anything in the evenings except eat, duh!  This was a wake up call.  All of this in only 3 weeks?  Really?  At this point, I knew it wasn't me just mentally beating myself up.  Just think about it...all of these physical symptoms from 3 weeks of bad choices.  What happens in a month, a year, or a lifetime?  If these little things can happen so quickly think about when I was younger and all I did was poor horrible food and a crazy amount of alcohol into my body.  Wow, the memories...This was a little bit of a wake up call for me.  I don't want to feel bad, fat, or not feel like playing with my kiddos.  I want to have energy.  So yeah a cheat meal here or there will keep the fatty in me satisfied, but lots of them will harm my body, make me feel like shit, and take away hours, days, or even years of my life.  I will not let food dictate my entire life or determine my or my kids happiness.  We all need healthy and happy families so choose food to fuel your body.