I understand fat freezing starts at-5. Is it safe to go higher, like -10?

mfountain,
The temperatures used in Coolsculpting have been rigorously evaluated to maximize fat reduction while maintaining a substantial safety margin. Continual temperature monitoring is utilized during the treatment to assure safety. During the treatment the skin reaches about -11 degrees Celsius with the superficial fat getting to about -8 or -9 degrees Celsius and the deeper fat reaching approximately 0 to +4 degrees Celsius. The temperature of the fat is the critical aspect of CoolSculpting to achieve cryolipolysis or fat cell destruction. The special CoolSculpting wipes used on treatment area lowers the freezing point of the skin and allows the skin to withstand the colder temperatures.
Be Well
Dr G - CoolSculpting University East Coast Medical Director

Careful monitoring of the temperatures with constant feedback, ensures that no burns occur. This is unique to CoolSculpt. One of the many reasons to only use Coolsculpting by a officially trained specialist who has been to Coolsculpting University.

CoolSculpting does not actually dip below 0 deg Celsius.  In fact it stays slightly above that.  Negative temperatures would certainly cause damage to fat cells, but it would also cause damage to skin and nerve cells.  The CoolSculpting machine carefully measures skin surface temperatures during the procedure to provide controlled cooling.  This prevents any skin or nerve cell damage.  
Hope this helps,
Dr. Garry K. Kim

The CoolSculpting machines are set at a specific temperature for a specific amount of time to keep the treatment as safe as possible, while still killing the fat cells in the treatment area.  This is something you should have done with a Certified CoolSculpting Specialist and should not be attempted at home. 

I'm not sure where you found the numbers that you used in your question i.e. -5 versus -10, but both of those numbers, whether Fahrenheit or Celsius, are not appropriate. Fat freezes at approximately 4°C and 39°F. There is no ability to set the temperatures lower on the CoolSculpting machines (at least that I'm aware of) and of course the FDA approval was based on the company recommended temperature settings and time of treatment. Overlapping areas that have been treated has been shown to increase effectiveness and we do this frequently in our practice. Dr. Adrienne Stewart MD FAAD

Fat apoptosis (cell death) occurs at a temperature of -10 to -13 degrees Celsius.  You will not get there safely without having a way to protect your skin so I would not recommend you attempt to do this at home.  Find a CoolSculpting Certified Practice and have it done there.  The results are predictable and the procedure is safe.