Any advice on how to diet effectively?

I am new to the diet world. I have always ate whatever I wanted, but hated the way I looked (definition of insanity right here). I've recently started running and I plan on completing my first 5K in February and I think a proper diet will help me shred unwanted pounds and increase my time. Any advice would be wonderful.

Do you need help in overall food choices or how many calories you should be eating?

I second the cutting portion, watch calorie intake (that's including what you drink, so try to stick with water, no sugary drinks and limit alcohol if you can), no processed food, and that every meal should consist of carb (non starchy if you can), lean protein, and good fat (think: avocado, olive oil, etc). The composition of those three might be differ depends on whether it's your exercise day or not, whether it's pre or post-workout, etc etc. As for your calorie intake need, you might need to calculate that depends on daily activity, age, metabolism rate, etc etc etc. Things can get complicated (and a bit science-y here).

But at the end of the day, to each his/her own. What works for others may not work for you. I found that what works for me is not a very strict diet, but rather a diet that keep me sane and I can stick to for the rest of my life. I have a cheat day ... otherwise, I'll go crazy and binge eating. ONE unhealthy meal is not going to make me fat, just like ONE healthy meal won't make me lean :-)

Good luck!

Thank you everyone for the advice. It's usually dinner that I have a hard time with. I want to eat heavy foods, like mashed potateos, breads, pastas, and fatty meats. I'll diet really well in the beginning of the day, but by the end I'm so hungry.

Plan better. If you're hungriest in the evening, then you need to eat the bulk of your calories in the evening.

Nothing at all wrong with the foods you mentioned. It's all about portion control.

Protein, protein, protein! I eat lots of lowfat yogurt, chicken breast and fish so that I don't binge on carbs at the end of the day. Carbs are my weakness! Because I know I cannot control my consumption I don't buy potatoes, bread, or pasta at the store. I set aside every Saturday to indulge in carbs so I don't completely deprive myself. Saturdays are my day to indulge on pastries, baked goods, mac and cheese or mashed potatoes.

I found the biggest breakthrough I had was actually listening to my body, not my plate. Take a moment while you are eating and feel if you are full. I also found that eating slower helps a lot in portion control (this might be obvious, but I've always been an Olympic speed-eater!). I let myself eat anything I want, but do it in moderation. I go light during the day and eat low-calorie meals and snacks so that at dinner I can have the freedom to eat what ever is being served. It's all about portion control and protein for me. Drinking lots of water helps you to feel full. I drink about two cups of natural green tea during the day also. I eat around 1200 calories/day, and it hasn't posed a problem yet. Most of my battle was getting used to eating less mentally, not physically.

Don't diet. Change your life and eat properly, with healthy food in moderate proportions. Do that forever and you will be fine.