Encouraging your body to surrender excess water and waste matter is really beneficial, but it is extra exercise for the kidneys and the colon, and like exercising any muscle, it should be built up slowly. I do not believe that prolonged periods of diarrhoea can be good for you because it is dehydrating, you lose beneficial minerals and it often gives you gripping pains. Diabetics are advised to consult their doctors or dieticians before changing their diet, but juicing mainly vegetables and diluting the juices with water has helped a lot of diabetics. Most fruit and vegetables have a high water content, which makes them possible to juice. Vegetable juices made from carrots, swedes, parsnips, make very good bases for blends.
Carrots are very neutral and taste completely different from expectation.
All fruits, especially apples, oxidise quickly and lose all their nutrients, I believe it is best to drink juice within 5 minutes of making. For Christmas I juice pineapple, kiwi and papaya mid morning to give us all an appetite before luncheon. Not only does it taste delicious, but it's also good for digestion. Pineapple is the only known source of Bromelain, a natural anti-inflammatory agent good for arthritic joints. Always try and wash your juicer straight after using it.