Losing up to 22 pounds in 13 days certainly sounds like a winning diet if you want to lose weight fast. However, the 13 Day Metabolism diet is a fad diet with strict rules and severe calorie restriction that you may have a hard time following for the allotted days.

Fat loss isn't easy. It requires a dedicated diet and exercise plan and permanent habit changes. Because most people are accustomed to instant gratification, the idea of taking the time to burn off stubborn belly fat is unappealing.

Eating right and working out requires sacrificing your time and some of life's simple pleasures. When you don't see results on the scale, you may be tempted to throw it over for snacks and computer games. Don't despair.

Stress affects people in a variety of ways. Some may lose weight, while others may gain. Both epinephrine and cortisol are adrenal stress hormones that might be partly responsible for these reactions. Cortisol increases your metabolism, but it also makes you hungry.

Swelling in different areas of your body -- generally from fluid accumulation in your tissues -- frequently is visible in your extremities.

Like adults, more and more children are having a hard time managing their weight. And an overweight child is more likely to become an overweight adult, according to the Centers for Disease Control and Prevention. Figuring out your child's body fat is one way to assess your child's health risk.

Both your weight and body composition are important for good health. No ideal body weight exists for anyone, but rather there is a range of acceptable weights for any given height. A doctor can advise you on whether you're at a healthy weight or have an increased risk of obesity-related health problems.

When you look at yourself in the mirror first thing in the morning, you see a belly that's flatter than at any other time during the day. This happens because you're coming off of a multi-hour fast -- which means that most of your food has been digested, so it can't cause any bloat.

Obesity has been linked to several health risks, including heart disease, diabetes and cancer. In addition, obesity, which is defined as a body mass index of 30 or more, may also be linked to difficulty breathing, wheezing and asthma.

Instead of aiming for an ideal weight, which doesn't necessarily exist, you may want to work toward a weight within the healthy range for your height.

The term "metabolism" refers to the chemical reactions that take place in your body each day, and the energy -- in the form of calories -- that's burned carrying out those reactions.

The body requires energy to sustain itself and perform all the functions of daily life. The process of converting nutrients from food into energy is called cellular respiration. The energy from this biochemical process is captured in a chemical called adenosine triphosphate (ATP).