Metabolism and Weight Loss: How You Burn Calories
Find out how metabolism affects weight, the truth behind slow metabolism and how to burn more calories.
You've probably heard people blame their weight on a slow metabolism, but what does that mean? Is metabolism really the culprit? And if so, is it possible to rev up your metabolism to burn more calories?
It's true that metabolism is linked to weight. But contrary to common belief, a slow metabolism is rarely the cause of excess weight gain. Although your metabolism influences your body's basic energy needs, it's your food and beverage intake and your physical activity that ultimately determine how much you weigh.
Your body needs more water when you are: In hot climates, more physically active, running a fever, having diarrhea or vomiting.
Metabolism: Converting Food Into Energy
Metabolism is the process by which your body converts what you eat and drink into energy. During this complex biochemical process, calories in food and beverages are combined with oxygen to release the energy your body needs to function.
Even when you're at rest, your body needs energy for all its "hidden" functions, such as breathing, circulating blood, adjusting hormone levels, and growing and repairing cells.
The number of calories your body uses to carry out these basic functions is known as your basal metabolic rate — what you might call metabolism. Several factors determine your individual basal metabolic rate, including:
• Your body size and composition. The bodies of people who are larger or have more muscle burn more calories, even at rest.
• Your sex. Men usually have less body fat and more muscle than do women of the same age and weight, burning more calories.
• Your age. As you get older, the amount of muscle tends to decrease and fat accounts for more of your weight, slowing down calorie burning.
Energy needs for your body's basic functions stay fairly consistent and aren't easily changed. Your basal metabolic rate accounts for about 70 percent of the calories you burn every day.
In addition to your basal metabolic rate, two other factors determine how many calories your body burns each day:
Food Processing (Thermogenesis)
Digesting, absorbing, transporting and storing the food you consume also takes calories. This accounts for 100 to 800 of the calories used each day. For the most part, your body's energy requirement to process food stays relatively steady and isn't easily changed.
Physical activity and exercise — such as playing tennis, walking to the store, chasing after the dog and any other movement — account for the rest of the calories your body burns up each day. Physical activity is by far the most variable of the factors that determine how many calories you burn each day.
You probably don't need scientists to tell you that your metabolism slows with age. But they're studying it anyway—and coming up with exciting research to help rev it up again. The average woman gains 1½ pounds a year during her adult life—enough to pack on 40-plus pounds by her 50s, if she doesn't combat the roller coaster of hormones, muscle loss, and stress that conspires to slow her fat-burning engine. But midlife weight gain isn't inevitable: By eating metab-olism boosting foods and following the path, you'll sleep better, have more energy, feel firmer, and notice your clothes are looser in as little as 2 weeks. Here's how:
You need to cut calories to lose weight. But going too low delivers a double whammy to your metabolism. When you eat less than you need for basic biological function (about 1,200 calories for most women), your body throws the brakes on your metabolism. It also begins to break down precious, calorie-burning muscle tissue for energy, says Dan Benardot, PhD, RD, an associate professor of nutrition and kinesiology at Georgia State University. "Eat just enough so you're not hungry—a 150-calorie snack midmorning and midafternoon between three meals (about 430 calories each) will keep your metabolism humming.
Rev Up In The Morning:
Eating breakfast jump-starts metabolism and keeps energy high all day. It's no accident that women who skip this meal are 4 1/2 times as likely to be obese. If nothing else, grab a yogurt. Or try oatmeal made with fat-free milk and topped with nuts for an essential protein boost.
Drink Coffee or Tea:
Caffeine is a central nervous system stimulant, so your daily java jolts can rev your metabolism 5 to 8%—about 98 to 174 calories a day. A cup of brewed tea can raise your metabolism by 12%, according to one Japanese study. Research-ers believe the antioxidant catechins in tea provide the boost.
Fight Fat With Fiber:
Research shows that some fiber can rev your fat burn by as much as 30%. Studies find that women who eat the most fiber in foods gain the least weight over time. Aim for about 25 g a day—the amount in about three servings each of fruits and vegetables.
Buy The Big Bottle:
German researchers found that drinking 6 cups of cold water a day (that's 48 ounces) can raise resting metabolism by about 50 calories daily—enough to shed 5 pounds in a year. The increase may come from the work it takes to heat the water to body temperature.
Eat Iron-Rich Foods:
It's essential for carrying the oxygen your muscles need to burn fat, says Tammy Lakatos, RD, coauthor of Fire Up Your Metabolism. Until menopause, women lose iron each month through menstruation. Unless you restock your stores, you run the risk of low energy and a sagging metabolism. Shellfish, lean meats, beans, fortified cereals, and spinach are excellent sources.
Get More Vitamin D:
This vitamin is essential for preserving metabolism-revving muscle tissue. Unfortunately, researchers estimate that a measly 4% of Americans over age 50 take in enough vitamin D through their diet. Get 90% of your recommended daily value (400 IU) in a 3.5-ounce serving of salmon. Other good sources: tuna, shrimp, tofu, fortified milk and cereal, and eggs.
Skip the Second Cocktail:
When you have a drink, you burn less fat, and more slowly than usual, because the alcohol is used as fuel instead. Knocking back the equivalent of about two martinis can reduce your body's fat-burning ability by up to 73%.
"There's some evidence that calcium deficiency, which is common in many women, may slow metabolism," says Laka-tos. Research shows that consuming calcium through dairy foods such as fat-free milk and low-fat yogurt may also re-duce fat absorption from other foods.
Your body constantly burns calories, even when you're doing nothing. This resting metabolic rate is much higher in people with more muscle. Every pound of muscle uses about 6 calories a day just to sustain itself, while each pound of fat burns only 2 calories daily. That small difference can add up over time. After a session of strength training, muscles are activated all over your body, raising your average daily metabolic rate.
Step Up Your Workout:
Aerobic exercise may not build big muscles, but it can rev up your metabolism in the hours after a workout. The key is to push yourself. High-intensity exercise delivers a bigger, longer rise in resting metabolic rate than low- or moderate-intensity workouts. To get the benefits, try a more intense class at the gym or include short bursts of jogging during your regular walk.
Eating more often can help you lose weight. When you eat large meals with many hours in between, your metabolism slows down between meals. Having a small meal or snack every 3 to 4 hours keeps your metabolism cranking, so you burn more calories over the course of a day. Several studies have also shown that people who snack regularly eat less at meal time.
Metabolism and Weight
It may be tempting to blame your metabolism for weight gain. But because metabolism is a natural process, your body has many mechanisms that regulate it to meet your individual needs. Only in rare cases do you get excessive weight gain from a medical problem that slows metabolism, such as Cushing's syndrome or having an underactive thyroid gland (hypothyroidism).
Unfortunately, weight gain is complicated. It is likely a combination of genetic makeup, hormonal controls, diet com-position, and the impact of environment on your lifestyle, including sleep, physical activity and stress. All of these fac-tors result in an imbalance in the energy equation. You gain weight when you eat more calories than you burn — or burn fewer calories than you eat.
A Closer Look at Physical Activity and Metabolism
While you don't have much control over the speed of your basal metabolism, you can control how many calories you burn through your level of physical activity. The more active you are, the more calories you burn. In fact, some people who are said to have a fast metabolism are probably just more active — and maybe more fidgety — than are others.
You can burn more calories with:
• Regular aerobic exercise. Aerobic exercise is the most efficient way to burn calories and includes activities such as walking, bicycling and swimming. As a general goal, include at least 30 minutes of physical activity in your daily rou-tine. If you want to lose weight or meet specific fitness goals, you may need to increase the time you spend on physi-cal activity even more. If you can't set aside time for a longer workout, try 10-minute chunks of activity throughout the day. Remember, the more active you are, the greater the benefits.
• Strength training. Strength training exercises, such as weightlifting, are important because they help counteract muscle loss associated with aging. And since muscle tissue burns more calories than fat tissue does, muscle mass is a key factor in weight loss.
• Lifestyle activities. Any extra movement helps burn calories. Look for ways to walk and move around a few minutes more each day than the day before. Taking the stairs more often and parking farther away at the store are simple ways to burn more calories. Even activities such as gardening, washing your car and housework burn calories and contribute to weight loss.
No Magic Bullet:
Don't look to dietary supplements for help in burning calories or weight loss. Products that claim to speed up your me-tabolism are often more hype than help, and some may cause undesirable or even dangerous side effects. Dietary sup-plement manufacturers aren't required by the Food and Drug Administration to prove that their products are safe or effective, so view these products with caution and skepticism, and always let your doctors know about any supplements you take.
There's no easy way to lose weight. The foundation for weight loss continues to be based on physical activity and diet. Take in fewer calories than you burn, and you lose weight.
Our knowledge is increasing about all of the mechanisms that impact appetite, food selection, and how your body pro-cesses and burns food. Your health care provider can help you explore interventions that can help you lose weight.