too fast?
 

Is is unhealthy to lose weight to quickly? as i have heard some people say. what is the reasons behind this, and what is a suitable and healthy weight loss?

Generally it is recommended that in the longterm you should aim to lose 1 to 2 pounds per week. If you have too great a calorie deficit you body tends to slow its metabolism to maintain its current state. You will lose weight but it may be slower than what would happen with a 500 to 1000 calorie deficit per day.

If you don't exercise while dieting, up to 50% of your weight loss could come from lost muscle rather than fat. It is easier for your body to catabolize muscle than it is recall and convert your stored fat to energy so you body takes the path of least resistance. Exercising helps to conserve your current muscle. Since muscle is the furnace of your metabolism the more you have the more calories your body burns, even at rest.

If you are in the morbidly obese category then you can safely lose much faster (5 pounds/week) than the 1 to 2 pounds/week (at least to start) as you have a higher percentage of bodyfat that your body can use for fuel.

I've lost over 77 pounds (300 lbs to 222.6) in just over 4 months. I feel good, I'm running with my family, everybody tells me I look good. I feel strong. I don't feel like I've lost weight too quickly at 4 lbs. per week.

I think it depends on how much overweight you are to start with, so what percentage of body fat you are losing. I have heard doctors telling people who start with a high percentage of body fat that they should lose 4-5 pounds a week. But as you get closer to your goal you will probably find that you can't lose as fast without depriving yourself of needed nutrients.

I started with a BMI over 42 and 300 pounds. I now have a BMI under 31 and weigh 222. Still losing weight at practically the same rate (it's slowed a little, but not much). Don't feel deprived on 1800 calories a day and vitamins. Definitely have much more energy and can do a lot more.

If you have been eating fairly to really unhealthy and haven't been exercising at all, the weight is going to come off faster with a change in diet. If you're heavier, it's going to melt right off in the beginning, to a certain point. The key is to not get discouraged along the way, because 1 pound in the beginning is just as important as 1 pound midway through and 1 pound at the end... you have to start somewhere, keep going and not give up. :)