**4. Conclusion**

Obesity is the consequence of an imbalance between energy intake and energy expenditure, and basic therapies for obesity are appropriate dietary restriction to decrease energy intake and effective exercise to increase energy consumption. However, maintaining these lifestyle modifications, such as diet therapy and exercise, are difficult and therapeutic effects are limited. Medical therapy then becomes a pivotal step.

It is important to elucidate the complex mechanisms of obesity in developing new antiobesity therapies, including the discovery of novel drugs. In particular, investigations using obese animal models are essential to clarify the pathophysiology and develop new antiobesity drugs. Several drug types that target various mechanisms, such as increased satiety with anorexia, inhibition of nutritional absorption, and acceleration of energy consumption, have been developed using various obese animal models including genetic models and nongenetic models. To help develop new antiobesity therapies, including the understanding of pathophysiology of obesity, the importance of the obese animal models will be a constant in the future.
