John,

Have you checked your thyroid function?  You can do this by simply taking
your temperature before getting our of bed in the morning.  Monitor your
temp. for a few mornings.  If the average is below 98 degrees this could
indicate a sluggish thyroid, which would cause weight loss to stop.

Do you exercise?  If your over 35 yrs. old, resistance training can help
maintain Lean muscle mass, resulting in higher metabolic rate.  Resistance
training can also stimulate proper hormonal balance.  Remember, weight gain
is not always fat gain.  Has your Body fat % changed at all during the months
of your weight plateau?

I believe "periodic" changes in your diet is healthy.  If you continue the
same diet regime, the body will "adapt".  Increasing your carb levels to Zone
ratios or perhaps above for a week or two, may allow your body do "un-adapt"
allowing you to realize new weight loss when you resume a low carb diet.  The
principles of "periodization" and "adaption" are sound scientific concepts
that are utilized successfully by strength athletes all the time.  To get
stronger, an athlete can't constantly increase weight loads.  If he does, he
will eventually overtrain, which results in strength plateaus and injuries.
 If the athlete uses the same amount of weight all the time, then the body
"adapts", resulting in no strength gains.  What's needed is a cyle of heavy
resistance followed by a period of lighter or less intense work that allows
the body to rest and recover before more intense work is started again.

I believe we can apply these concepts to diet in order for us to achieve
goals of optimal weight, health, and variety/enjoyment in what we eat.

Try to stay positive.  Be willing to experiment.  Hope this helps. Good Luck!

Ed Campbell, DC,CSCS