Weight-loss quiz: Brush up on slimming down

The biggest influence on your weight is what you eat and how much you eat, not when you eat. Weight is dependent on the balance of calories consumed versus calories burned. Take in more calories than your body needs and you gain weight. Take in less and you lose weight. It makes no difference what time of day you consume these excess calories.

If your body uses 3,500 calories more than you take in, you lose a pound of fat. You can lose weight two ways by eating fewer calories or by increasing the number of calories your body uses through physical activity. The best way to lose weight is to combine both approaches.

Even a low-fat diet can lead to weight gain. This happens if you cut back on fat but take in excess calories. Items such as fat-free cookies, ice cream and pretzels still provide a substantial number of calories. And too many calories from any source result in added pounds.

Carefully check food labels for both fat content and total calories. Some processed foods touted as low-fat or fat-free are high in calories and offer little nutritional value. Fruits and vegetables, on the other hand, are naturally low in fat as well as calories and are high in nutritional value. Pay attention to fat, calories and nutrients in all of the foods you eat. All three are important: looking only at the fat grams doesn't tell you all you need to know.

You may think herbal supplements are safe, but many contain active ingredients that can harm you if taken with certain prescription or over-the-counter drugs. Some of these products can even cause serious problems on their own. For example, ephedra (ma-huang), a plant-derived chemical containing ephedrine, was commonly used in weight-loss supplements until it was found that it can cause dangerous side effects, including heart attacks, seizures, strokes and sudden death. For this reason, the Food and Drug Administration (FDA) prohibits the sale of products containing ephedrine or related products to consumers.

Herbal supplement manufacturers aren't required by the FDA to prove their products are safe or effective, so view these products with caution and skepticism. Don't use them unless you have thoroughly researched the ingredients for potential side effects.

Despite what some products or weight-loss plans claim, no foods burn fat. Fad diets, such as the grapefruit diet or the cabbage soup diet, claim to promote quick and easy weight loss. You may lose weight following one of these plans, but any pounds you drop are either the result of cutting calories or from fluid loss — not from any fat-burning properties in foods.

It may seem logical to think that significant weight gain or being overweight is related to a low metabolism or possibly even a condition such as an underactive thyroid gland (hypothyroidism). In reality, it's quite uncommon for low metabolism to be the cause of excess weight. And most people who are overweight don't have an underlying condition such as hypothyroidism. However, a medical evaluation can determine whether a medical condition can be influencing your weight.

Gastric bypass surgery alters the anatomy of your digestive system in order to limit the amount of food you can eat at one sitting. This is major surgery, and it's not for everyone who has a problem with obesity.

Generally, surgery for weight loss is reserved for people who are severely overweight and who have health problems as a result. Surgery for obesity may be considered if:

• Your BMI is 40 or higher (extreme obesity)
• Your BMI is 35 to 39.9 (obesity) and you have serious weight-related health problems such as diabetes, high cholesterol or high blood pressure

In order to keep the weight off, you need to continue eating healthy foods, limiting your portion sizes and exercising regularly. If you stop, you'll likely gain the weight back. Your ultimate goal is to incorporate the new, healthy behavior into a routine — a natural part of your daily life. This is why, when starting a weight-loss plan, you need to find one that you can continue for a lifetime.