7 months, 50 lbs. lets see: down to the raw physics of it...
3500 calories in a pound; multiply that by 50.
175,000 calories you need to burn off in 7 months.
7 = around 210 days.
175,000 / 210 =would need to have a calorie deficit of around 833 calories a day to make this happen.
If you are 200 lbs (random guess, just cuz it's a nice even number) you burn off about 2000 calories as a basil metabolic rate. (basically add a zero to the end of your weight), this does not include any activity you do durring the day.
so you would need to eat a minumum of 1200 calories, with a maximum depending on how active you are of about 1400- 1500.
It is completely possible, if you can stick with it the whole way. if you put in some excercise you can add calories to what you can eat for the day.
Here is an activity calculator--it's got a lot of them on there. just make sure to take away the calories you would have already burned during that time from the total once you add the other ones.
For example: if you work out on an elliptical trainer for 15 minutes and weigh 200 lbs, you burn off 163.6 calories during that 15 minutes, but you have to subtract the basal metabolic rate for that 15 minutes because it is included in the calories burned on the elliptical.
* if you weigh 200, you burn off 1.38888 calories per minute, simply existing.
-proof: 2000 calories/ 24 hours = 83 and 1/3, 83 and 1/3 calories per hour / 60 mintues per hour = 1.3888 repeating calories per minute.
* if you weigh 150, you burn 1.04166666 calories per minute, simply existing.
Proof: same as above- calories per day divided by hours per day, divided by minutes per day.
this is merely the bare sketch. So much depends upon a red wheel barrow...i mean on what you fuel your body with. if you eat a lot of fiber you lose weight faster and stay regular, despite the diet changes. If you drink lots of water and don't eat too much sodium your body will not retain water as much and the results of your efforts will be easier to see.
Your body would like to remain at homeostasis-When you gain weight your body is slightly uncomfortable (feeling stuffed from eating too much or feeling lethargic from sitting too long), when you lose it, that happens to, weather it's with a little bit of hunger, or it's from the muscle burn when you are exercising.
I wish you the best of luck on your weightloss journey. Keep us updated on your progress, and remember, if you need any support, feel free to whine to us, we listen becuase we've been there/ are there.