What is the likely outcome if you eat junk food and also take phentermine?

Gain weight . Phentermine has no effect on making unhealthy food....Healthy. Just by taking Phentermine - you will not lose weight if you do not eat healthy/ low fat/ low cal/ high protein...
Gain weight. Phentermine is an aid for appetite suppression. This is how you lose weight by eating less. If you eat high calorie junk food you will gain weight.