I would avoid any extreme crash diets to get your weight down. The most effective way to make long-term changes in your diet and overall health is going to be making smart changes over time. I think the biggest problem in shaming yourself out of eating junk is that it creates this ugly relationship with food where you start first demonizing certain foods and then start demonizing yourself for wanting them. This can create a binge and purge cycle that is anything but healthy and only furthers the dark feelings associated with food and with yourself.

If I might make a suggestion: rather than abruptly stopping eating junk food, start crowding out junk food with good stuff. People who eat high-sugar diets have a literal addiction to sugar which alters the way you perceive foods. Healthy food may taste more bland or bitter than it should for a while. It helps to find things you like (even if they are a little sweet); replace sugary processed fruit juice with fresh fruit or whole-fruit smoothies. Replace sugary cakes with whole-grain breads with a little honey on top. Experiment and find healthier alternatives that you like, and as your sugar levels normalize, you may find yourself liking things you didn't before.

Fast change my produce more immediate results, but slow change is much more realistic and healthy both for your body and your mind. Never punish yourself for slip ups, just keep on keepin on till you make your way into a diet that works for you and your body. Remember, starvation might make you lose weight, but nutrient depletion will open up a whole host of other issues. if food is your obsession, find ways to make that passion work for you rather than against you.