The global incidence of obesity continues to rise and is a major driver of 
morbidity and mortality through cardiovascular and cerebrovascular diseases. 
Animal models used in the discovery of novel treatments for obesity range from 
straightforward measures of food intake in lean rodents to long-term studies in 
animals exhibiting obesity due to the continuous access to diets high in fat. 
The utility of these animal models can be extended to determine, for example, 
that weight loss is due to fat loss and/or assess whether beneficial changes in 
key plasma parameters (e.g. insulin) are evident. In addition, behavioural 
models such as the behavioural satiety sequence can be used to confirm that a 
drug treatment has a selective effect on food intake. Typically, animal models 
have excellent predictive validity whereby drug-induced weight loss in rodents 
subsequently translates to weight loss in man. However, despite this, at the 
time of writing orlistat (Europe; USA) remains the only drug currently marketed 
for the treatment of obesity, with sibutramine having recently been withdrawn 
from sale globally due to the increased incidence of serious, non-fatal 
cardiovascular events. While the utility of rodent models in predicting clinical 
weight loss is detailed, the review also discusses whether animals can be used 
to predict adverse events such as those seen with recent anti-obesity drugs in 
the clinic.