Obesity has become a world-wide epidemic; in the United States (U.S.) approximately two-thirds of adults are classified as overweight or obese. Military veterans' numbers are even higher, with 77% of retired or discharged U.S. veterans falling in these weight categories. One of the most common methods of changing one's weight is through dieting, yet little is known regarding the factors that facilitate successful dieting behavior. The current investigation tested the Theory of Planned Behavior's (TPB) ability to predict dietary intention and future dieting in a sample of 84 overweight and obese patients attending medical clinics at a Veterans Affairs Hospital in the southwestern part of the U.S. Participants primarily were male (92%) and ethnic/racial minorities (58%). Perceived need and anticipated regret were added to the standard TPB model. While the TPB predicted dietary intention, it did not significantly account for improved dietary behaviors. Anticipated regret significantly enhanced the basic TPB's ability to predict intention to diet, while perceived need did not. These findings highlight the difficulty in predicting sustained change in a complex behavior such as dieting to lose weight. The need for more work with older, overweight/obese medical patients attending veterans' facilities is stressed, as is the need for such work with male patients and ethnic minorities in particular.