The diet industry will tell you to eat 1200 calories a day of "clean foods" in conjunction with weight training and cardiovascular session to get shredded. End of story.
While these protocols may be effective, there are other methods to get lean that don't involve set parameters such as those mentioned above. An individual could still get lean enough to reveal a chiseled midsection without restricting himself/herself to "clean" foods, while doing his/her preferred exercises, and with or without any additional cardiovascular training sessions. How?
The "Secret"
The secret to getting a six-pack is energy balance. Think calories in (eaten) versus calories out (burned).
No top secret diet foods, no highly specific training methods, and no time spent on a cardio machine will magically reveal a trim and sculpted ab area unless energy balance is taken into account.
Food has a corresponding number of calories, regardless if it is considered "healthy food" or "junk food". Different calorie sources can have different impacts on the brain, energy expenditure, hormones and hunger, but the body does not work with a simple on and off switch that will automatically store "junk food' as fat, and "healthy food' as fat-free mass. So as long as you are under your daily caloric allotment for weight loss each day, you can and will lose weight even while eating junk food.
Know Your Maintenance Calories
Your maintenance calories are the number of calories you need to consume to support life and your daily activities. If you are a very active who, for example lifts boxes all day, you will require higher maintenance calories than someone who is sits at a desk the majority of the time.
If you are under your maintenance calories, your body will burn its stores to fill the energy gap. This means burning calories that you already have stored, which includes body fat. Being under maintenance or in a caloric deficit will deplete body fat stores, resulting in a leaner physique and six-pack abs.
The Case for Satiety
Consuming 200 calories worth of lettuce is more filling than 200 calories of Reese's peanut butter cups because you get more food volume per calorie with the former. When dieting down, hunger management is one of the things you'll have to consider especially during the tail end of your diet when calories have been reduced pretty significantly.
If you consume calorie-dense foods such as pizza and ice cream early on in the day, you might not have enough calories left over for your nighttime meals. This could result in overeating or going over your caloric targets for the day, both of which are counterproductive for getting lean.
This is where planning your meals and accounting for satiety will be key to the success of your diet. "Junk food' tends to be more calorie-dense and less filling than "clean food,' so learning how to balance the two to suit both your physical requirements and mental needs (think: cravings) will most certainly come in handy.
Do What Works for You
You don't need to eat "junk food' or "unhealthy food' if you don't want to. You are free to eat lean proteins, leafy vegetables and fruits if you choose to. You can also eat pizza and ice cream once in a while, as long as it doesn't put you over your daily caloric targets.
What matter is that you now possess the knowledge on how to get a shredded six-pack without forcing yourself to eat boiled chicken breast and broccoli, or tilapia and asparagus 6 times a day for 12 weeks only for you to gain all the weight you've lost on that one cheat day.
Getting lean doesn't happen overnight, and you'll want to lose fat at a rate of 1-2 pounds per month to preserve lean muscle tissue. Unless you want to eat paper and be miserable for the duration of your diet, learning how to incorporate "fun' foods into your diet is an example of how you can practice flexible dieting techniques to better achieve your goals.