Hello Annie,
I am a 20-year-old male, 6'4'', and 165 pounds. My friends describe me as especially skinny, but there is a kind of secretive irony to that image. I have a very small frame for a man my height because I spent the better half of my young life severely overweight, and my muscles atrophied. To this day I suffer from insecurities, and I still feel echoes from my unhealthy past - for this reason, I am almost always on a strict self-imposed diet. This tends to baffle my peers, since to them, I am thinner than a rail (almost unhealthily so). The reason why I am so obsessed with loosing weight is that I have still retained a good amount of baby fat (that I failed to burn off during my "fat" years) that gives me an uncommonly childish appearance, and burning off baby fat is not easy to do with typical American eating habits.
As a result I've fallen into a strange pattern. I diet very strictly, exercise 5 days a week and then I spent the weekend eating whatever I want. This is a pretty normal approach to dieting that works well for many people, but for me, I have been noticing a big difference. When I have my "splurge" meals I tend to take it over the top, and stuff my face well after I've satisfied my stomach. I feel pressured to eat all of the foods that I won't be able to eat tomorrow, and wind up eating unnatural portions of food. It feels very forced and uncontrolled and I strongly dislike myself when I get into that mindset (it is definitely a mindset). Then, the next day, I am overwhelmed by guilt and eat very little throughout the day - sometimes under 1,000 calories. It is a very unhealthy habit that materialized from a relatively effective dieting technique. Unfortunately, I don't see an easy way out of it. I'm not willing to give up dieting until I have the chiseled manly features I've been seeking for so much of my life, but the strictness of the diet seems to be the cause of the over-the-top splurge days. After the splurge days, however, I need to diet more strictly to make up the difference.
This is my dilemma. However, as I was formerly overweight (and managed to drop 40 pounds in a month) I can offer some advice. Your body is a machine. The amount of fat you burn or gain each day is as easy as simple addition. If you consume more calories than you burn off during your day-to-day activities, you will gain exactly the amount of weight that you failed to burn off. One pound of fat is 3,500 calories. So if you eat an extra 500 calories each day, you'll be gaining a pound each week. Most human beings burn about 2,000 calories in a day. So if you eat 2,500 you will quickly gain weight. The average fast food meal contains 1,000 or more calories.
There are a variety of metabolic rate calculators available on the internet. Use them to find out how many calories you burn each day, and then chart your calories to make sure that you come in under the amount you've burned. You will lose weight - mathematically, you have to. You should aim to eat 500 calories less than you burn each day, so that you can loose 1 pound each week.
This is a good basic system to begin with, but it's more complicated than that. Hormones dictate how you lose weight. If you are low in hormones such as HGH and Testosterone (regardless of gender) your body will be less apt to burn fat than it should be. The way to restore these hormones is almost so cliche it's silly: eat your fruits and vegetables, and get at least 20 minutes of INTENSE cardio each day. This will literally re-wire your brain to produce fat-burning hormones instead of fat-storing ones. You should also eat the right kinds of fats and proteins. This is essential. I've seen so many diet plans that remove fats and meats. This will deplete your energy, give you cravings, make you miserable, and generally reduce your physical health. A good source of healthy fat and protein is peanuts, whole grains, chicken, lean red meat, etc. All of this food is fantastic for you in the right amounts, and from the right place (not a restaurant).
The great thing about this approach to dieting is that you feel great and stop craving the foods you're addicted to. I highly recommend this, since it put me in a DRASTICALLY improved physical condition (with a little commitment, of course). I am still have problems with my weight - what do you expect when I've spent so much of my life overeating - but I've made monumental progress.
It feels much better to be proud of yourself for achieving a significant life goal than eating another Whopper. Trust me.