I have been hearing a lot about isagenix for losing weight and for giving the body total nutrition. Is it safe?

Hard to say. Though most fad diets are generally useless for long term weight loss. Most of them do not work, and if they do, you usually will not be able to keep the weight off after you stop it. The best for weight loss continues to be dieting and exercise. Bariatric surgery is a last resort at this time, but is becoming more common.
Good question. It depends what you are using it for, it depends how you are using it. Everyone is individual and its hard to give a blanket statement saying it is safe for everyone. Some people have special metabolic issues- for example - where they dont make or tolerate certain forms of folate (folic acid), (folic acid) Isogenix has folate (folic acid). You should consult your doctor and review your medical history before starting to take it.