Slim

Answer: Loose or saggy skin can be a common problem after losing a large amount of weight (more than about 50-100 lbs) in a short period of time. In time, you may see improvements in your skin's elasticity, but some people may require surgery to remove excess skin.

According to Plastic Surgery Guide Natalie Kita, the main factors involved in your skin's elasticity include:

Age: As you get older, your skin becomes less elastic. Genetics: Genes influence how much firmness your skin retains as you get older. How much weight you lose: When you lose a large of amount of weight in a short time, such as with weight loss surgery, your skin doesn't have time to shrink along with your body and may be permanently stretched if you're overweight for a long period of time. Sun exposure: Your past, present and future exposure to the sun can damage your skin. Nutrition and water intake: Your skin may not be as healthy or firm if you aren't getting balanced nutrition, vitamins and minerals (especially Vitamins C & E) and staying hydrated. Smoking: Smoking can speed up the normal aging process of your skin.

Because we're all different, each person will have a different response after losing weight. Some people may bounce back quickly while others may need to consider body contouring surgery to get rid of extra skin. Natalie recommends waiting at least a year after weight loss before considering plastic surgery to allow your weight to stabilize.

Remember that body contouring surgery is an expensive and serious surgery requiring a long recovery time. You may be able to make a difference with other options, such as exercise and a healthy diet. A basic cardio and strength training program can help you reduce body fat while building muscle. When you add muscle, you can improve how the skin looks and may be able to reduce some sagging.

The best way to avoid loose skin is to lose weight slowly, about 1-2 pounds per week. Slow weight loss allows you to maintain muscle mass while losing fat and it also allows your skin to adjust as you lose weight.

Sources:

Escoffier, Catherine, et al. Age-Related Mechanical Properties of Human Skin: An In Vivo Study. Journal of Investigative Dermatology (1989) 93, 353–357.

Vaidya V (ed). Body Contouring following Massive Weight Loss Resulting from Bariatric Surgery. Adv Psychosom Med. Basel, Karger, 2006, vol 27, pp 61-72.

Source: http://exercise.about.com