Since I went on my first all-body detox, a couple of years ago, I learned how to overcome cravings for sugary foods - which I find give instant energy, but do not sustain. Since then, I pack in huge salads, which greatly improved my skin tone and condition - cracked heels, flaky skin etc and food transit time through the body. At the detox (which was a week under controlled conditions at a lovely Spanish organic farm) we ate no solids, just electrolyte broth, veg juices and gut cleaning herbs. They did not recommend aggressive and risky colonic vacuum cleaners. Just natural methods.
It sure revealed the guck that accumulates in our systems. Even after not eating for 7 days, my guts had emptied the last of the old crap stuck in the corners and dark recesses. So eat your veggies and ease off on putrefying foods, sticky white breads, cakes and stuff that comes in boxes and packets, and bloating, yeasty beer. Nowadays I grow much of my own food. It's easy to forget what real food tastes like. Stick with the good fats - olive oil and neither heated too strongly, which turns good fats into bad.
Anyone wishing to learn how to fully detox could try "Detox International". They really know their stuff. A note: it might seem hard to go without food for a week, but it's actually very easy, so long as you keep up the electrolytes. Though never drink too much water in a day or at any one time - water is toxic in large quantities as it imbalances the electrolyte level in the bloodstream and you can fall down and die.
A further note on detoxing. As the body becomes less burdened with processing food, the organs, skin and fat cells release stored toxins, which can manifest themselves as skin conditions (rashes, patches etc), but consider that a good thing because, it is what is coming out. So work through it and have confidence that a detox is doing you good. After a few days, the toxic effect will disappear and your skin begin to glow and feel great. I did not encounter any skin conditions, probably as I already ate quite healthily and toxins were eliminated normally. After that, put only good fuel in. You don't put crap in the car's gas tank, after all.