The IRS rules for deducting the costs of a weight loss program are set
forth in IRS publication 502 and read as follows:

"You can include in medical expenses amounts you pay to lose weight if it is
a treatment for a specific disease diagnosed by a physician (such as obesity,
hypertension, or heart disease). This includes fees you pay for membership
in a weight reduction group as well as fees for attendance at periodic
meetings. You cannot include membership dues in a gym, health club, or spa
as medical expenses, but you can include separate fees charged there for
weight loss activities.
You cannot include the cost of diet food or beverages in medical expenses
because the diet food and beverages substitute for what is normally
consumed to satisfy nutritional needs. You can include the cost of special
food in medical expenses only if:
1. The food does not satisfy normal nutritional needs,
2. The food alleviates or treats an illness, and
3. The need for the food is substantiated by a physician.
The amount you can include in medical expenses is limited to the amount by
which the cost of the special food exceeds the cost of a normal diet...."
"You cannot include in medical expenses the cost of a weight-loss program if
the purpose of the weight loss is the improvement of appearance, general
health, or sense of well-being. You cannot include amounts you pay to lose
weight unless the weight loss is a treatment for a specific disease diagnosed
by a physician (such as obesity, hypertension, or heart disease). If the
weight-loss treatment is not for a specific disease diagnosed by a physician,
you cannot include either the fees you pay for membership in a weight
reduction group or fees for attendance at periodic meetings. Also, you
cannot include membership dues in a gym, health club, or spa.
You cannot include the cost of diet food or beverages in medical expenses
because the diet food and beverages substitute for what is normally
consumed to satisfy nutritional needs. "

Thus, the disease of obesity, appropriately diagnosed by a physician,
allows one to deduct from one's income any fees incurred for weight
control provided that the conditions set forth above are met.

References:

1:IRS Publication 502 (2009), Medical and Dental Expenses:
http://www.irs.gov/publications/p502/
2: IRS Publication 502 (2009)--weight loss section:
http://www.irs.gov/publications/p502/ar02.html#en_US_publink1000179034
I.R.S. Rules For Deducting Weight Loss Costs From Income Taxes
Copyright Notice:
This work is protected by a
United States Copyright and
unauthorized use may result in
civil penalties.The contents of
this website, except where
explicitely noted, are the
original works of
Holland
Medical Inc.
and may not be
copied or reproduced in any
form including but not limited to
printing, photography or digital
(electronic) reproduction
without the prior written
permission of
Holland Medical
Inc
.