What kind of juices may be helpful in a diet for weight loss?

None. Make sure you exercise at least 30 minutes a day, don't skip meals, avoid soda, juice, dairy, alcohol and fried foods. Eat a healthy well balanced diet! also water, organic vegetable broth, green leafy vegetables, natural pickles, apples are great to fill you up so you dont feel hungry and they are very low in calories.
Dilute juice, +fiber. Drinking juice beverages (with or without fiber) can help with weight loss only if they don't increase the total amount of calories eaten per day. For example, mixing water with powdered fiber to make a drink will cause a person to feel fuller and have less appetite (can be helpful). However, mixing fiber with undiluted juice will give a person lots of sugar calories along with fiber (won't help!).