Besides eating healthy (low-fat), you need to exercise to lose weight. Basically weight loss boils down to burning more calories than you consume. You can lower the calories you consume, by eating lower fat healthy food. At the same time you can increase the calories you burn by exercising. I don’t recommend you jump off the couch, and try to run 10 miles. You need to work into it.
My wife has pretty much been a couch potato for a bunch of year, and eating unhealthy at the same time. Guess what! She’s overweight! Real surprise there. But she has been starting to practice healthier eating habits. I have tried to get get her to exercise. I bought her a cheap treadmill, but she didn’t like it. She liked playing video games, so I bought her Dance Dance Revolution hoping she would get into that. She did play a it a few times. Just a few times. I bought her a better treadmill. She used it a few times. Again, just a few times. I ended up using the treadmill (I am scheduled to run 24 miles tomorrow! ack!). I bought her an elliptical trainer. HIT! She uses it!!!! I bought her a used but quality bicycle late last year, and have overhauled it over the winter in hopes that she would get into riding. ANOTHER HIT! We have been going on bike rides together!!! I got her to sign up for swimming which she had been talking about for a long time! HIT!!!! She has been going swimming! I keep kidding her that with the swimming, bike riding, and elliptical she is training for a triathlon and doesn’t even know it! LOL!
I am proud of her though. I just hope she keeps it up. She is doing a great job!
I just got off the treadmill after running 13 miles. I didn’t just decide to run that distance. I am following a marathon training schedule, and today I was scheduled to run 13 miles. I used a Polar brand heart rate monitor. According to the heart rate monitor, there were 1900 calories burned over the course of my run.
My goal was to run long slow distance (LSD), and keep my heart rate under 150 BPM. I wanted to stay in the aerobic zone. So the majority of those 1900 calories were probably fat calories.
Following my run, I was starving, so I ate a small tub of fat free cottage cheese with pineapple. 10 grams of protein, and 17 grams of carbs per serving. And the tub contained 4 servings. I ate the whole thing, for 440 calories! Now I have a boneless skinless chicken breast on the grill, and will make a couple chicken sandwiches with lettuce and tomatoe, and just a light spreading of mayonaise. Yum!
And I still have a karate class this afternoon. 
Next Sunday I get to run 14 miles! Such fun!
Along with eating low fat, to lose weight, you need to exercise. You can just go out there, and start running, but if you are out of shape, chances are you are jut going to get tired, burned out, and possibly injured. You need to start slowly! Thats where a heart rate monitor comes in.
With a heart rate monitor, you can exercise intelligently. Yur heart rate is a great indicator of your effort level. If you are out of shape, it doesn’t take much to get your heart rate up. When you get into better shape, you will have to physically work harder to get your heart rate up.
When you raise your heart rate up to a certain level, you enter the aerobic zone. In this zone, you are burning mostly fats. As you increase your level of effort, your heart rate increases, and you begin to enter the anaeobic zone. In this zone, you begin to burn more glycogin (sugars), and less fats.
Fats are like charcoal, and glycogen is like lighter fluid. The charcoal will burn slow, but for a long time. The lighter fluid will burn fast, but we gone quickly. You need glycogen to get the fats to burn. But as you go anaerobic, you are burning just the glycogen. Also as you go anaerobic, your body starts producing lactic acid faster than it can get rid of it. This is what makes your muscles sore after a hard workout. And when you burn all the available gycogen, your body wants to stop. Working out in the aerobic zone, also increases your chances of injury. And repeated anaerobic workouts will wear your body down.
So for the most benefits, it’s best to stay in the aeobic zone. This is where the heart rate monitor comes in. It allows you stay in the zone. It tells you when you need to speed up, or when you need to slow down.
If you are just starting out, a basic heart rate monitor such as the Polar FS1 will work fine.
A couple excellent books on the subject are Heart Monitor Training For The Compleat Idiot by John L. Parker Jr. and also High Performance Heart by Phil Maffetone.