Many people wrongly assume that if they simply lose weight, they'll get rid of sagging skin. The problem is, many diets focus on losing pounds, but it's pounds of fat and muscle if you don't do it right. And when you lose muscle, your skin loses its tone.

Sagging skin isn't folds of fat. It's the result of skin that's not being supported by underlying muscle. That's why people who are "thin" often have floppy underarm skin or folds above their knees—like the now-famous images of Demi Moore's knees before her rumored plastic surgery. Once your skin detaches itself from the muscle, it ages quickly. Skin stays healthy by attaching itself to muscle and being nourished by it.

Our body is not meant to be too skinny. The first reason we have muscles is to be able to move, and the second is that muscle fills us out and gives us shape.

Hanging and unhealthy skin is the result of:
* Losing weight too fast
* Poor nutrition
* Dieting without exercise
* Dieting plus endurance exercise
* Dieting plus low-range-of-motion strength training
* A diet low in vegetables

The good news is that you can regain toned arms and legs no matter how old you are. Here are six solutions:

1. Don't lose weight too fast. Don't embark on a crash diet, such as a liquid diet that promises to help you lose 30 pounds in 30 days. A healthy rate of weight loss—that is, losing weight while building muscle—is 1-2 pounds per week. Sagging skin can happen when we lose weight too fast. The slower the weight loss, the more time for the skin to adapt and not lose its elasticity and connection with muscle.

2. Eat food rich in vitamins C, E, A, B complex, and K; essential fatty acids; and three minerals—selenium, copper, and zinc. All these muscle-and-skin-supporting essential nutrients can be found in vegetables, fruits, animal protein, grains, nuts and vegetable oils, but mostly in: asparagus, bell peppers, broccoli, spinach, cauliflower, garlic, olives, leafy greens, bananas, vegetable oils, flax and safflower oils, flaxseed, rice, salmon, sardines, mackerel, oysters, poultry, eggs, and lean meat.

3. Never lose weight without exercise. If you lose weight without exercising, you will lose weight but you will also lose underlying muscle tone. The muscle will not grow in the area where you lose fat and the skin will wrinkle and hang.

4. Never do endurance exercises while losing weight. If you lose weight by dieting and with endurance exercises—such as treadmill, stationary biking, or jogging—you will lose fat and lose muscle. This is the worst scenario for losing weight; the skin will wrinkle and hang the most. Instead, do resistance training and speed lifting using light hand weights. This builds muscle while burning fat.

5. Use the full range of motion while strength training. If you lose weight by dieting and low range of motion strength training, you will not gain enough muscle in the area necessary. For example, if you do a half squat you will gain muscle in your thigh but not in your knee area, therefore the skin around knees will wrinkle and hang. Lifting weights that are too heavy will also lead to hanging skin.

6. Eat twice as many fruits and vegetables as any other food at lunch and dinner. If you do not eat enough fruits and vegetables, your body will develop chronic inflammation and your skin will lose elasticity.

Aniela and Jerzy Gregorek are world weightlifting champions and founders and head coaches of the UCLA weightlifting team. Aniela is a 5-time World Weightlifting Champion who holds six world records. Jerzy is a 4-time World Weightlifting Champion with one world record. They own a successful diet and fitness coaching practice in LA, and have written a new book about their approach, which has helped hundreds of people achieve their ideal size, called "The Happy Body: The Simple Science of Nutrition, Exercise, and Relaxation" (www.thehappybody.com), winner of six national and international awards in the category of health and fitness books.