Is the Emsculpt treatment 'wasted' if you are dieting? Would someone on a big calorie deficit not really benefit from it?

Emsculpt will build muscle mass and reduce fat in patients who are dieting.  The treatment will add to the benefits of your diet, exercise, and weight loss program.  Good luck and be well.Dr. PEncino, CA

Emsculpt is performing supramaximal involuntary contractions which is different than what you can do at the gym.  The body cannot mimic this on its own.  Physical movements through exercise are voluntary contractions. So you are actually getting even more of a benefit than working out.  Emsculpt will be especially effective if you are already active and dieting.  Best of luck!

The Emsculpt treatment is not wasted on someone who is dieting...in fact, the two work very nicely together. 
As you have probably read, the treatment itself is akin to getting 20K crunches (for the abdomen) in a half-hour session. The natural process that results from the treatment will reduce the fat in this area. Add in a well-planned diet and the effectiveness will only increase. The key here is ensuring that your diet is 'well-planned' and contains an adequate amount of protein for the building of muscle. As always, consult with a dietitian before starting on a diet that involves a significant caloric deficit. 
One patient that has utilized our Emsculpt treatment following a significant weightless using a high-protein, low carb, low calorie approach (800-1000 calories a day) has reported excellent results - particularly in fitting into clothing. In a three week period he indicated clothing fitting much better in the midsection as "abs had tightened up nicely" for him. 
Best of luck and thanks for your question.

Your muscles respond to the hyper stimulation from Emsculpt to grow, so as long as you have some calorie reserves in your body your daily dietary intake is not going to affect the results.
As I have treated patients over the last six months many patients have come to the same view as you and just think of this as hyperexercising since they couldn't do 20,000 ab crunches by themselves let alone in thirty minutes. That alone makes it worth it. 
Next comes the question of maintenance. If it really is just like exercising what do you have to do to maintain the benefits. Well obviously you have to be back in the gym but some of my patients have chosen a maintenance package of Emsculpt instead which is fine too because ultimately what burns fat is muscle. That's why weight training is much better for weight loss than aerobic exercising.