If you're overweight or if you've been overweight in the past, then you know that getting rid of excess pounds is only one of the challenges you face. Once the fat is gone, you are often confronted with an equally frustrating cosmetic problem; Loose skin.

I know this is a big problem because I receive a ton of e-mail from people who have loose skin or from overweight people who are concerned about having loose skin after they lose the weight. Just recently, I received this email from a reader of my syndicated “Burn The Fat” Q & A column:

“‘Tom, I began a fat loss program using your Burn The Fat program and it worked so well I got down to 15 1/2 stones (from 19). However, this has caused me a problem: Excess abdominal skin. I didn't crash lose this weight, it came off at the rate of about 2 lbs. per week just like you recommended. Now I'm unsure of whether to carry on, as my abdomen has quite a lot of excess skin - I feel like I've turned into a bloody Shar-Pei! (You know, that ‘wrinkly’ dog!)

Does everyone go through this? Will the skin tighten up? I was overweight for more than 12 years. Am I going to end up needing surgical skin removal? Can you offer me any advice? I'm a medical student in the UK and my colleagues seem determined to proffer surgery as the only option.”

There are 12 things you should know about loose skin after very large weight losses:

1. Skin is incredibly elastic. Just look at what women go through during pregnancy. Skin has the ability to expand and contract to a remarkable degree.

2. Elasticity of skin tends to decrease with age. Wrinkling and loss of elasticity is partly the consequence of aging (genetic factors) and also a result of environmental factors such as oxidative stress, excessive sun exposure, and nutritional deficiency. The environmental parts you can fix, the genetics and age part, you cannot. Advice: Get moving and change the things you have control over... Be realistic and don't worry about those things you don't have control over.

3. How much your skin will return to its former tautness depends partly on age. The older you get, the more an extremely large weight loss can leave loose skin that will not return to normal.

4. How long you have extra weight and stretched skin has a lot to do with how much the skin will become taut after the weight loss: For example, compare a 9 month pregnancy with 9 years carrying 100 excess pounds.

5. How much excess weight was carried has a lot to do with how much the skin will resume a tight appearance. Your skin can only be stretched so much and be expected to "snap back" one hundred percent.

6. How fast the weight was gained also has a lot to do with how much the skin will resume a tight appearance. Your skin can only be stretched so quickly and be expected to "snap back."

7. How fast weight is lost also has a lot to do with how much the skin will tighten up. Rapid weight loss doesn't allow the skin time to slowly resume to normal. (yet another reason to lose fat slowly; 1-2 pounds per week, 3 pounds at the most if you have a lot of weight to lose, and even then, only if you are measuring body fat and you’re certain it's fat you’re losing, not lean tissue).

8. There are exceptions to all of the above; i.e, people who gained and then lost incredible amounts of weight quickly at age 50 or 60, and their skin returned 100% to normal.

9. There are many creams advertised as having the ability to restore the tightness of your skin. None work – at least not permanently and measurably – and especially if you have a lot of loose skin. Don't waste your money.

10. If you’re considering surgical skin removal, consult a physician for advice because this is not a minor operation, but keep in mind that your plastic surgeon may be making his BMW payments with your abdominoplasty money. (It’s possible that surgery may be recommended in situations where it's not 100% necessary). Surgery should be left as the ABSOLUTE FINAL option in extreme cases.

11. Give your skin time. Your skin will get tighter as your body fat gets lower. I've seen and heard of many cases where the skin gradually tightened up, at least partially, after a one or two year period where the weight loss was maintained and exercise continued.

12. Know your body fat percentage before even thinking about surgery. Loose skin is one thing, but still having body fat is another. Be honest with yourself and do that by taking your body fat measurement. This can be done with skinfold calipers or a variety of other devices (calipers might not be the best method if you have large folds of loose skin. Look into impedance analysis, underwater weighing, DEXA or Bod Pod).

Suppose for example, a man drops from 35% body fat all the way down to 20%. He should be congratulated, but I would tell him, "Don't complain about loose skin, your body fat is still high. Press onward and keep getting leaner.”

Average body fat for men is in the mid teens (16% or so) Good body fat for men is 10-12%, and single digits is extremely lean (men shouldn’t expect to look “ripped” with 100% tight skin on the abs unless they have single digit body fat, and women low to mid teens).

Except in extreme cases, you are very unlikely to see someone with loose skin who has very low body fat. It's quite remarkable how much your skin can tighten up and literally start to “cling” to your abdominal muscles once your body fat goes from “average” to "excellent." Someone with legitimate single digit body fat and loose skin is a rare sight.

So... the key to getting tighter skin is to lose more body fat, up to the point where your body composition rating is BETTER than average (in the “good” to “great” category, not just "okay"). Only AFTER you reach your long term body fat percentage goal should you give thought to "excess skin removal." At that point, admittedly, there are bound to be a few isolated cases where surgery is necessary if you can’t live with the amount of loose skin remaining.

However, unless you are really, really lean, it's difficult to get a clear picture of what is loose skin, what is just remaining body fat and how much further the skin will tighten up when the rest of the fat is lost.