Question

It should only be a problem is your caloric intake for the day is below 1200 calories. Generally after you enter all of the foods you eat for the day and all your exercise you can click on the complete this entry at the bottom of the food diary. There will be a message explaining what you should weigh after five weeks if your eating pattern continues. If you have not eaten enough calories for the day it will give you a warning that you may not be getting enough of the proper nutrients because it gets harder the less you eat.

This is completely false. It's bad if you're not eating all your calories because MFP has already figured out how much you need to eat to lose weight. When you exercise, you need to eat those back because they're extras that are not figured into what MFP has given you. If you leave too many calories, your body isn't getting enough fuel to energize and support your body, muscles, etc. and it can slow weight loss or make you gain. It happened to me, trust me on this one. A LOT of people will tell you the same thing.

The best way to avoid having so many calories at the end of the day after exercise is to plan out how much you think you'll burn before you burn it. Put it in your log and then "spend" your calories throughout the day. It's a good way to keep yourself accountable to the exercise but also so you don't get to dinner and have a lot of calories to eat at once. Easy ways to eat up those extra calories are:

almonds - 1/4 cup 190 calories
natural PB - 2 tbsp 170-200 calories
large banana - 100 calories
protein shake POST work out (get whey and find one with low sugar and about 100 or so cals for 1 scoop and at least 20g protein) - this will help with soreness from working out as well as eating up cals (mix it with milk and add fruits, veggies, nuts, whatever you want), helping you meet your protein goal (which should be 20-30% of your diet), and help your muscles recover so they can grow and get strong.

Hope this helps!

The other way to go is to take exercise into account in the daily calories and always eat that which sounds like what you are doing. The point is to eat enough. Not like eating 1000 Cals and exercising 2 hours a day.. To keep it healthy is all about keeping the daily deficit optimal, getting reasonable amount of exercise, and resting enough. There are very good reasons behind the recommended 1 lbs a week pace for losing weight. especially if you only have something like 10 lbs to lose.

Thinking that you can speed things up by eating less than you need to is a lie and leads to ruin!