if you're still eating a lot of ice cream, chips, soda, and other junk food, it may not do much. just eating healthy can help anyone live better 90% of the time. the other 10% is exercising. so if you don't watch what you're eating, it may not have much of an effect.
don't be afraid to see a doctor either. get a physical if it's been more than a year. you know you have some issues, so go get the help you need and make some changes. find a buddy to workout with or have your family go on a same diet plan.
if you have a smartphone, use it. there are a lot of calorie counter apps out there, and find one that breaks down nutrients to fine tune your diet.
study up. read online what to eat and not to eat. you can also ask your doctor. work out a realistic, healthy eating plan and go from there. stick with it for a month then change it up as necessary.
some people need months if not a year to see healthy changes for the better. patience and consistency is key.