I find it truly amazing how many fads, gimmicks and such there are out there telling people if you do this then you will look like this. Really if it were that easy our country wouldn't have a weight problem. If you want to be healthy you have to work for it. There are those who were blessed with great genes that can eat whatever they want and such, but those are few and far in between, and honestly I would love to be that person, but I'm not. I have to work hard and if you want to be healthy you do too.
Really it is basic math. To gain 1 pound you have to eat an additional 3500 calories more than your body needs to function. To lose 1 pound you have to burn an additional 3500 calories more than your body needs to function. Simple easy math.
Now the hard part. You have to figure out how many calories your body needs a day. *For me if I were to lay in bed every day and do nothing my body needs about 1000 calories. Then when you figure in my daily activity level which is lightly active it comes to about 1400 per day. Between folding laundry, vacuuming, playing with the kids, cooking, reading and sitting here on the computer. There are times that I am more busy than some and other times that I am a total couch potato so really it all balances out.
You can do online and use any one of many sites that will give you your BMR (basal metabolic rate) from there you will know what you need for your age/height/weight. Many of these sites will also give you information about how many calories you need dependant on your activity level. Once you get that information you are ready for the next step. A healthy weight, which I will cover next time.
The site that I use is http://www.myfitnesspal.com/ I have not been asked to write this, it is all me.
*This is my data every person's needs are different. DO NOT go off of my calories for you. My doctor and I have discussed my needs and this is what I was told.