Wolf,
I have a better idea now so it is easier to say something.
Firstly, look in the mirror and tell me the colour of the top of your tongue. This will tell me the state of your digestion.
If you eat the pizza BTW, do yourself a favour and don't eat the cooked cheese. It is indigestible when cooked. You may as well eat rocks. Spread it on after it is cooked.
To bump up your digestion here is some possibles that are inexpensive and easy,
1. get either a copper cup or a copper penny, clean it well with soap or lemon, (the first day) rinse well. Before going to bed, put water in the cup or put the penny in a regular cup with water. Do not use hot water or heat it in the cup. In the morning brush your teeth and use a spoon to gentle scrape off the gunk from the top of your tongue and spit out what's in there. Do not swallow it. Then drink the water.
2. Make high meat this way. Buy say 1/2 to 1 pound of the best quality grassfed organic meat (fish, beef, pork, chicken or whatever else you like) you can afford. Not ground meat. Cut it up into nibble sized pieces, say the size of your thumbnail or less, put it all in a clean jar large enough that it is at the most half full. Make sure the jar has a lid that is not damaged so it does not rust. Put the lid on it. Put it in the fridge and leave it there for 30 days. Air it out once every three days but do it outside cause it will stink.
After 30 days in the fridge, take it outside the house, open it and use a fork or spoon to fish out a piece. Have something to chase it with in case the taste is too strong. Chew it a bit and swallow it. The taste and smell may gross you out so holding your nostril also may help. It doesn't bother me but it grosses out my GF. Women tend to have a heightened sense of smell compared to men.
Air out this jar at least every three days, (not to worry if you are a bit slack here) Have some of this every day or every three days or whatever. The more the merrier. This will do you for quite awhile. What this will do is repopulate your gut with healthy bacteria.
When there is oxygen in the jar the healthy bacteria grow well and it kills the bad bacteria.
3. Before you eat a meal, mix a tiny bit of salt with an equal amount of raw ginger and an equal amount of lemon juice. Have a pinch of this before you eat. Chew it up as well as you can. It will get the digestive juices flowing so you will have better digestion. If you don't have one of these ingredients it will work with the other two,
According to Ayurveda (my experience is in this method) you have acne because your digestion is not optimal and there is food that is not being digested, that makes it's way into the bloodstream and circulates around till it finds a place to settle. When it gets there, it collects and then essentially it rots. The body's immune system kicks in and surrounds this stuff with blood which causes the red appearance and then it attacks the undigested food which is foreign material as far as the body is concerned. After it attacks the Ama (Sanskrit for undigested food) the white blood cells form a pustule.
As far as your weight goes, in order to gain weight you have to get the digestion working properly. Your body type is similar to mine in that you could eat a horse and not gain much.
The best exercise for you is walking and light stretching like Yoga or Pilates or something along those lines.
Poor digestion is the main cause of all disease. (it's not the only but a main cause)
You can also increase digestion by going for a 20 minute walk after your meal. There is lots of things I could suggest but this is plenty for now.