meaning this is not reason to indulge. in another study, rats were fed a western diet high in fats for 90 days and their learning and memory skills suffered. sometimes you don't need a study to tell you that. our sixth story, the u.s. on high alert. marines beefing up security at the american embassy in nairobi following the deadly terrorist attack at a shopping mall there. the state department is also warning other terrorist attacks could be in the works by al qaeda-linked grooms. while it has not been confirmed, we can tell that you kenyan officials are implying the woman known as the white widow did have involvement in the attack. her name is samantha lewthwaite and she is the widow of a bomber. tonight there is a worldwide alert to hunt her down. brian todd is "outfront." >> reporter: she's been photographed as a british school girl with a soft faced smile. she is now called the white widow. is believed to be a jihadist and interpol has issued a notice