everything as watchout said, i only wanna add something. i lost 15 kilos in a year without going to a doctor, only modifying the way i ate and of course doing sports, so i think i can speak  here :)

first of all reduce the quantity of cheese and animal fat to almost 0%.  replace cheese with 0.1% fat yoghurt and non-fat (or half fat=) milk as you need calcium, and eat turkey and fish and boiled eggs for proteins. chicken is fat despite what many people think.
increase the quantity of vegetables and fruit, but never mix different types of fruit and have it between breakfast and lunch, and between lunch and dinner.
prefer carbohydrates for lunch and proteins and vegetables for dinner.
never mix different types of proteins.
don't use fat or at least use olive oil - i know it isn't easy there, tho - for cooking.

control the calories of what you eat. if there are no nutritional values on what you buy, don't buy it.
the quantity of the food you eat matters A LOT when you don't burn your calories. i mean if you workout 6 days a week of course you need to increase your energy otherwise you would collapse. but what you eat metters a lot too.
remember that a kilo of fat = 3000 calories. when i work out 2,5 hours my cardio tells me i burn around 600 calories, and about 50% of them is fat (the others are carbs) so in 2,5 hours i only burn 100 grams of fat, imagine if i didn't do anything...
on the other hand, if you eat food which equals 3000 calories, you gain a kilo.
the problem is, apart that the way you look like does matter, despite what many people say - it matters a lot because we live in a society where some stupid people judge you for what you look like also when you are applying for a job - there is the health factor, which is fundamental.

when this becomes a lifestyle, exceptions are allowed. i sometimes go out for a pizza, and of course every now and then i also have things like fries or others which aren't too healthy, actually... only every now and then is good, and helps us not getting frustrated.
i only wish i started with all this at least 10 years ago...