1) Eat the right amount of calories. I cannot even begin to tell you how many people have told me the following: "I work out almost every day and I'm eating 1500 calories, and I'm SO FRUSTRATED, because I'm not losing weight!" My response is always, "You're not eating enough calories." It is a scary concept to eat more calories when you've got your mind set on eating less. But this makes your body go into "Starvation Mode" and keep a kung fu grip on your weight. Sure, you will lose some weight initially, but it will not be sustainable.
To find out the calories you should be eating, first, find out your Basal Metabolic Rate (BMR). Then, follow the instructions here for the Harris-Benedict Equation. This will tell you how many calories you need to maintain your current weight. A healthy calorie reduction is 500 calories per day. Since there are 3,500 calories in a pound, a 500 calorie per day deficit would result in a weight loss of 1 pound per week. This is healthy weight loss. Which brings me to my next point...
2) Real weight loss is slow. Sorry.
3) Fad diets don't work. Repeat after me: Fad diets don't work. Atkins is BS (seriously--what about eating loads of fatty meats and no carbs sounds like a non-artery-cloggingly good idea?!). The Celebrity Juice/Cookie/Only-Eating-One-Type-of-Anything-Diet(s) are totally ridiculous. Slimfast works temporarily only because you are replacing two meals per day with liquid, which, again, is crazy. South Beach limits fruits for the first several weeks (ridiculous--fruit is good for you, for christ's sake). Even that "Skinny Bitch" book which tries to shame you into losing weight is really just brainwashing you into becoming vegan (which, as you should know, is a very serious lifestyle change that requires a lot of consideration and careful diet planning).
The only way to lose weight healthily is to eat a balanced diet with moderate portions. Model your diet after the USDA food pyramid. Primarily, eat whole grains, fresh fruits and vegetables, milk, lean protein, and heart-healthy fats.
4) If you're really hungry, eat something. This should go without saying, but people often think that you need to starve to lose weight. This goes back to my first point. If you're at your calorie limit for the day and you are STARVING, you should eat something. Try to limit yourself to a 100-calorie snack if fresh veggies don't cut out the craving. Sugar-free pudding with berries, low-fat cottage cheese, a spoonful of peanut butter, a few crackers....none of these things will kill your diet.
5) It's okay to splurge. A lot of people are most successful with dieting when they allow themselves to cheat. Once a day with something very small (like a square of chocolate) or once a week with something larger (like a serving of Ben & Jerry's). Giving yourself these treats will make you less likely to cheat in larger ways. Ultimately, the calories will not matter.
Additionally, If there is a special occasion like a wedding or an anniversary meal, do not just eat a salad. You should enjoy yourself, because food is a wonderful way to celebrate such occasions. Obviously, you shouldn't go overboard with a huge porterhouse and two slices of chocolate cake. But get something reasonable that sounds good, have a glass of wine, and split a dessert. Trust me, you will be so much happier.
6) Know Thy Food Groups. I've actually had people get mad at me because alcohol is considered a fat serving, frozen yogurt a starch, and Yoplait Whips (the only 'tolerable' yogurt, dontchaknow?) not a milk serving, but a starch. Seriously, people. Man up. No, you can not eat frozen yogurt instead of milk or yogurt (what are you, 12 years old?!). No, your super-sugary yogurt does not count the same way plain, non-fat yogurt does. I'm very sorry that alcohol is metabolized as fat, but I don't make up the rules. Margaritas are fatty and high-calorie. Deal with it.
It's important to know the caloric and nutritional parameters of what makes a food group a food group. Calculating food exchanges is what the American Diabetic Association does. This is too confusing to go into while writing a doctrine, but I will revisit it some other time.
7) Walk More. Walking is the single easiest way to lose weight and maintain your weight loss. By simply parking your car at the end of the parking lot, getting up and walking to your coworkers instead of emailing them, taking a 15 minute walk during your lunch hour, and/or a 30-minute walk after dinner, you can make a noticeable dent in your progress. If you're able to, walk to work and take a bus home (or vice-versa). I find it's helpful for most people to get a pedometer and wear it throughout the day. There are roughly 2,000 steps per mile--it's fun to find out how many miles you walk normally and try to build off of that number.
8) Mix it up. Once you get used to an increased activity level, start incorporating other forms of exercise. Your body will get used to the same activity if you're doing it over and over again for an extended period of time, and it will lose its effectiveness. This is why you need to shake things up. It's important to walk almost every day, but try adding in cardio (i.e. Zumba, Tae Bo, Aerobic dance, or elliptical machines) once or twice per week, and then muscle-building activities like Yoga or Pilates another one or two days.
9) Cook for yourself. It's all fine and well to go out to eat, but it's difficult to manage calories and portion sizes (**SIDE NOTE: I would make a separate bullet point about portion sizes, but I'm getting tired of writing....and I'll make it a separate entry). Learn to cook healthy foods for yourself and your family if you don't know how already. Learn healthy substitutes for what you already make for your family (another topic I'll broach in the future). Finally, subscribe to Cooking Light magazine--they are a godsend.
10) You've got to really want it. Weight loss is difficult. Keeping it off can be even harder. You have to really WANT to stick with it through the pain and deprivation. You have to really want the end result. If you don't care enough about the process, you will probably fail. This usually results in 'cycling,' where you lose weight, gain weight, lose weight, and so forth. Cycling is typically disappointing and shameful to the dieter. You don't wanna go there--it's an ugly state of mind. So, steel yourself. Get used to the idea of change. You'll be happier in the end.
Questions? Fire away.