if you eat mostly fresh fruits and mix them properly (check out food combining information) you will heal your body the quickest and lose weight the best. I made a thread about this in the Healing section if you are open to reading my lengthy post but it is very important information I shared. You can eat a lot of fruit too and it will just help you lose more weight and get healthier as long as you eat it as we're supposed to.
when unhealthy exercising too much can be bad because exercise creates acids like lactic acid in the body, which when ill the body cannot detoxify it out very well.
but for the best exercises interval training is the quickest way to achieve the lactic acid effect which exercise is generally for and for that you just have to do high volume activity (like running fast or jumping rope or on a trampoline or swimming if you're lucky enough to have access to a nice body of water) for about half a minute (or even 10 seconds if you want to start lower)
and then do low activity (like walking or doing pilates or something) for a minute or two, or half a minute if you want. You can experiment but you really don't have to put forth all that much effort to exercise the body efficiently.
truly most people are just wasting time and taxing the body.. however of course it is wonderful to move the body and various yoga and mindful movements of the body and dance and such have much more effect than mere 'exercise'. if you like certain sports that can be great too especially if you have a person or people you enjoy doing them with.
one specific type of yoga exercises worth checking out is the 5 Tibetan Rites and it may be perfect for you because the rule is to start out slowly and you only do 3 of each exercise for the first days, then move up gradually. with a total of just 21 of each exercise being the goal once you work up to that level but you can take months to do it if you want.
The 5 Tibetan Rites are said to work the entire body and spiritual centers like chakras too
here's one source for information about the 5 rites but there are others you can explore and also youtube demonstration videos
http://www.mkprojects.com/pf_TibetanRites.htm