I don't know what I am doing wrong

Have you looked into getting a heart rate monitor? You could target your training to specific zones to promote fat burning. :glasses: Please don't give up because you can do this. If all else fails see your doctor and let he or she know what you've been doing and see if there's an underlying health issue to blame.

I have been working out for 5 months (about 4 times a week, varying strength and cardio), eating right using MFP and staying within calories but I have only lost 8 pounds. MFP keeps saying if you keep this up you'll be XXX lbs in 5 weeks. But I am still no where near that!! So frustrating.

I want to give up. How do I stay motivated? How do I explain this low weight loss? (I am 6 feet and weigh 177 currently- although this past week my weight inexplicably went up 3 pounds!!)

I'm in the same position as you! It's SO annoying...and extremely discouraging.

You may not be eating enough calories and that affects your metabolism, making you gain weight or difficulty in losing weight. I also had that same problem, I lost a huge amount of lbs. but stayed on plateau in 4 months and even gained 3-5 pounds. Only to realized that I was eating too few calories. Although the calorie goal specified in MFP can be helpful but you need also to know your daily calorie needs for you to maintain your weight. For you to lose a pound a week, there should be 3,500 calorie deficit or 500 daily. So from your daily calorie intake, you subtract 500 to determine the right amount of calories you need to take in during the day. Also you can do this by just staying on that calorie needs and burn 500 calories daily or a combination of both diet and exercise (-250 calories in from food, +250 calories out from exercise).

For you to determine your daily calorie needs, first you need to know your basal metabolic rate (BMR) or the amount of calories your body naturally burns just by simply functioning. This is the formula for determining the BMR.

Women: BMR = 655 + ( 4.35 x weight in pounds ) + ( 4.7 x height in inches ) - ( 4.7 x age in years )
Men: BMR = 66 + ( 6.23 x weight in pounds ) + ( 12.7 x height in inches ) - ( 6.8 x age in year )

Then once you know your BMR, you can calculate your Daily Calorie Needs based on your activity level using the Harris Benedict formula. The more active you are, the more calories you need to take in. Multiply your BMR by the appropriate activity factor, as follows:

If you are sedentary (little or no exercise) : Calorie-Calculation = BMR x 1.2
If you are lightly active (light exercise/sports 1-3 days/week) : Calorie-Calculation = BMR x 1.375
If you are moderatetely active (moderate exercise/sports 3-5 days/week) : Calorie-Calculation = BMR x 1.55
If you are very active (hard exercise/sports 6-7 days a week) : Calorie-Calculation = BMR x 1.725
If you are extra active (very hard exercise/sports & physical job or 2x training) : Calorie-Calculation = BMR x 1.9

Then from there, you can actually know the amount of calories you need to eat to lose weight. And if you lose weight, your BMR and daily calorie needs will change too & which is why its easier to lose weight when we are heavier and then we struggle to lose the remaining pounds once we are already lighter. When you lose weight, don't forget to re-compute.