As far as I know AFAIK, meal-replacement powders have one of two expected uses. <br><br>First is as a diet aid. In this category the attempt is to provide sufficient nutrition combined with insufficient calories. Or the more creative provide nutrition that is extremely weak in a specific area depending upon the dieting theory being attempted. They may contain no protien or no carbohydrates or no fats depending upon the approach.<br><br>Second as a body building supplement. These often overload the balance in favor of the nutrition needed to repair muscles that have been over-worked. This may be a better option if you plan on being on the move but it still doesn't fit. The type of work done during body building is mostly anaerobic while the work done hiking is mostly aerobic.<br><br>This having been said I carry both mainstay rations and some more readily available diet meal-replacement food bars that are rather tasty. They are the calorie reduced type of diet theory and as such provide a decent balance of vitamins and protien. I supplement calories from available carbo sources from hard candy to potatoes and anything in-between. I wouldn't want to live exclusively on them because of the lack of fiber. I have lived on them for a few days on occasions when I am simply too busy and broke to stop for a burger. (this actually happens to me). Payday usually saves me from this fate within a week so I haven't tried anything longer. I have never had any luck actually losing weight this way since I will double up on the food bars in order to quench the hunger. I always keep some in store for the lean / busy times.<br><br>I would avoid using the body-building types or the types that endorse an unbalanced nutrition scheme. Calorie restriction isn't that good during a stressful time either but it is easier to compensate for by carrying sugar or fat. sugar is perhaps easier to carry but fat is much greater calories for same weight by a factor of 9 I think.