本文建構一個關於個人參與減肥療程的決策模型，以檢測快樂與減肥行為是否有正向關係，及不同快樂程度的人在減肥行為上之差異，進而估算具有不同快樂程度的人，針對不同減肥療程願意支付價值之差異，同時，亦估算願意支付價值在不同快樂程度間之變化。實證結果顯示，快樂程度越高的人，確實會有較高的可能認為其需要減肥、且有較高機率參與減肥療程，並願意付出較高的療程價值。而在僅靠吃藥及吃藥配合運動的兩種減肥療程上，「很快樂」的群組均比「很不快樂」的群組具有較高機率認為需要減肥且願意付出較高的療程價值。具體而言，亦即一旦進入減肥療程，不論運動配合吃藥或是僅吃藥的療程中，「很快樂」的群組分別比「很不快樂」的群組，每年每人分別願意多支付25,783 及50,691 元，而不論參與何種減肥療程，願意支付價值由「很不快樂」至「快樂」，基本上是隨著快樂程度增加而提升。然而，此一現象對於「很快樂」的群組則不適用，因為是一群樂天知命，已無所謂他人對自己外貌評價的人。

The purpose of this paper is to construct a model of decision making in
which a positive relationship between characteristics of happiness and the
weight loss treatment programs are examined and the impact of various
degree of happiness on the weight loss is testified. It is then further to
estimate and compute the differences between the willingness to pay
(WTP) for weight loss treatment for persons with different degree of
happiness. The results show that persons with happiness characters do
have high tendency to lose weight and further have higher probability to
join different weight loss treatment programs and their WTP values are
more than those with unhappy character. More specifically, the group of
persons with “very happy” character is willing to pay NT$ 25,783 more than
the group with “very unhappy” character once they join the weight loss
treatment program with medication along with exercise. Similarly, people
with “very happy” character are willing to pay NT$ 50,691 more than the
group of people with “very unhappy” characters once they join the weight
loss treatment program with medication only. These results indicate that
the WTP for weight loss increases as people become happier. However,
this phenomenon does not apply to the group with character of “very
happy” who are satisfied with what they look and what they are now.