Hi Terry, I just do the Master Cleanse if I'm only doing 10 days, and juice fasting if I go longer. I too can't afford to lose anymore weight, I'm about 110lbs and 43 this year ;-)
However if you read Stanley Burrows book on it or Tom Woodrow (? can't recall off the top of my head) you can do it so you don't lose any weight and if you need to gain weight you will. In fact in Tom's book there is one testimonial I recall from a martial artist who did a long fast (more then the 10 days) and he gained 8 pounds of muscle!!! which he said was no small feat since he only weighted about 140ish pounds (sorry going from memory here).
I never feel as amazing off the cleanse as I do on it.... just like being high! the mental clarity, brain fog disappears, body aches and pains disappear and emotional crap too!!! but a couple days isns't enough ;-( it can take that long just to get past the hump and or headaches etc. for some...takes to about day 6 for serenity and mental clarity to set in for me ;-) i've been doing them off and on over the years in between having my 3 kids ;-)