I remember looking into the Candida cleanse by Dr. MaCombs and I believe that the two would work together just fine. The Candida thing involves taking a series of supplements which kill the Candida while avoiding sugar in all its forms. The Simmeons diet is far more restricted and there is nothing on it that is outlawed on the Candida diet except for oranges which McCombs says are often infested with different funguses which can inhibit the kill-off of the Candida...so just cross that off your weight loss menu and go with grapefruit instead.
The Candida diet is SIGNIFICANTLY longer. It takes a total of 16 weeks I think. 2/3 of that time you take a supplement to kill off the Candida in your body (esp your in your digestive tract) and the rest of it you take a probiotic which fills your system with good bacteria so that there are not a lot of "free parking spaces" for the Candida to take up residence in.
Candida yeast is a natural part of your digestive homeostasis and the goal is not to elimate it completely...instead your goal is to nuke the mutated "fungal" form which spreads through the body and causes problems and limited the "normal" yeast form to its proper, low level in the intestine. Once this is done there is a lot of "free space" (mentioned above) in the intestine that the yeast form can reproduce in and then mutate back into the fungal form.
This is why the probiotic is so important. You need to fill that free space with the good bacteria which, presumably, you destroyed at some point in the past by taking oral antibiotics. Then, of course, you never take those types of antibiotics again...or if you are so sick you are forced to, you do it in concert with a probiotic.
One of the scary "unknown" things with doing both at the same time has to do with toxins. Your body is going to release a lot of them as it processes your abnormal fat reserves. It will also do the same thing when rooting out the Candida...so you have the potential of having double the toxins running through your system from working these two processes simultaneously.
A key part of the MaCombs plan is sweating in a traditional dry sauna or a new infrared sauna for a good period of time to "sweat out" these toxins. He says it is so crucial to the program that if you are NOT willing to do the sweating then you have not business doing the Candida cleanse. I'd say this goes double if you are doing Simmeons and MaCombs at the same time.