Beginning natural bodybuilding when you are overweight is extremely difficult, if not impossible. You will not be abled to lose weight and body build at the time, the main reason being to lose weight you have to decrease the amount of calories you consume through your diet. When body building workout you actually have to increase the amount of calories you consume through your eating habits.
This of course does not mean you should not lose weight while working out. Exercise and working out is essential to losing weight, it is of course the type of exercise that you do that is most important. If you are overweight, you have two main goals that you need to achieve first. The first one is that you must lose weight before doing anything else, all the while making your muscles stronger. The second goal you need to work towards is actually building your muscles. Remember to try and reach one goal at a time to avoid over working yourself.
Begin with proper nutrition and a healthy diet. Starving yourself thin is definately not the answer. You may lose the weight, but you will also lose your valuable muscles, and cause yourself a variety of other serious health problems, potentially fatal along the way. If you decide to starve yourself to your goals, you will more than likely fail. You ultimately need proper nutrition, and you need to be prepared to do it for potentially a lifetime. Bodybuilding is a lifelong endeavor.
Seek the professional advice of your health care professional. Let them advise you how many calories you will need to consume each and every day, how many fat grams, etc, so that you can reach your weight loss goals efficiently and safely. You may also want to seek advice from a nutritionist. Seeing as though your second goal is body building, you will more than likely succeed quicker with a low-carbohydrate diet, since these particular diets focus on the intake of more proteins, which are vital for body building.