EVAL-AD5940BIOZ measurement data comes in nearly discrete magnitude steps

Hello,

I'm performing test measurements with the EVAL-AD5940 BIOZ 4-wire BIA. However the measurement data most of the time oscillates between different neraly discrete magnitudes (see attached images). I tried to change some settings of the EVAL board but the stepping effect is always present. I want to monitor fast changes of the impedance which is impossible when the changes are always fixed in magnitude. 

I used following settings for the measurements displayed in the figures:

  .bParaChanged = bFALSE,
  .SeqStartAddr = 0,
  .MaxSeqLen = 0,
  
  .SeqStartAddrCal = 0,
  .MaxSeqLenCal = 0,

  .ReDoRtiaCal = bFALSE,
  .SysClkFreq = 32000000.0,
  .WuptClkFreq = 32000.0,
  .AdcClkFreq = 32000000.0,
  .BiaODR = 20.0,
  .NumOfData = -1,
  .RcalVal = 10000.0,

  .PwrMod = AFEPWR_HP,
  .HstiaRtiaSel = HSTIARTIA_5K,
  .CtiaSel = 16,
  .ExcitBufGain = EXCITBUFGAIN_2,
  .HsDacGain = HSDACGAIN_1,
  .HsDacUpdateRate = 5,
  .DacVoltPP = 800.0,

  .SinFreq = 80000.0,

  .ADCPgaGain = ADCPGA_1,
  .ADCSinc3Osr = ADCSINC3OSR_2,
  .ADCSinc2Osr = ADCSINC2OSR_22,
   
  .DftNum = DFTNUM_4,
  .DftSrc = DFTSRC_SINC3,
  .HanWinEn = bTRUE,

  .SweepCfg.SweepEn = bFALSE,
  .SweepCfg.SweepStart = 10000,
  .SweepCfg.SweepStop = 150000.0,
  .SweepCfg.SweepPoints = 100,
  .SweepCfg.SweepLog = bTRUE,
  .SweepCfg.SweepIndex = 0,

  .FifoThresh = 4,
  .BIAInited = bFALSE,
  .StopRequired = bFALSE,
  .MeasSeqCycleCount = 0,

What could I change to solve this issue?

Thank you for your help!

Bjoern