除饮食和运动外，影响体重的十大因素
10 Things That Affect Your Weight Besides Food and Exercise
BY MELANIE RADZICKI MCMANUS
It may frustrate you that your friend Savannah can pack it in like a trucker, eschew any form of exercise and be model-thin. Meanwhile you're eating small portions of healthy foods, hitting the gym for 45 minutes daily and still fighting the battle of the bulge. Could your lack of weight-loss success be due to a slow metabolism? Or because you're big-boned? Or something else?
Debates around weight, food and exercise have raged for decades. Can you be fat and fit? Does a fast or slow metabolism signal your body-weight destiny? How much dieting and exercise is enough or too much? What we know for sure is this: The number that shows up on the scale depends on the number of calories that you consume, burn up and store. The thing is, each of these factors may be affected by things initially beyond your control. Here are some of them.
10.Hormonal Changes
One of the top hormonal changes that can cause weight gain in women is menopause. About 35 percent of American women between 40 and 59 are obese [source: CDC]. When women go through menopause, their estrogen levels drop. Animal studies show that estrogen helps control weight — lab animals whose estrogen levels declined tended to eat more and exercise less. Further, some experts believe a lack of estrogen can throw off the body's ability to properly use starches and blood sugar, which can also result in packed-on pounds [source: WebMD].
Another hormonal imbalance linked to increased fat deposits concerns leptin, a hormone that sends signals to your body that you're full. People who consume too much fructose in their diets (both from natural foods, such as fruit, and from processed foods) can end up with too much leptin in their bodies. Too much of anything isn't good; when your body has too much leptin in it, your brain ignores its signals. Thus you don't realize you're full, and you keep eating [source: Gottfried].
9.Water Retention
Your body can retain water for many different reasons. And if it does, that translates into higher numbers on the scale. One big cause of water retention is the type of food you eat. Fatty and salty foods, in particular, can cause your body to hold on to water. And the amount you retain is tied to how much activity you get during that same day. If you ate a lot of salty foods, but exercised an hour or two, you might not retain any excess water. But if you ate those same salty foods and didn't exercise (where you can sweat out water), you might end the day up a few pounds. In fact, your body can store as much as 5 extra pounds (2 kilograms) of water per day [source: Everson].
So how can you tell if you're retaining water versus gaining weight? Water retention pounds can come on in a single day, so if your weight suddenly shoots up within 24 hours, that's a likely culprit. You may also notice a swollen abdomen, and/or swelling in the ankles, fingers, feet and face.
If you're prone to water retention, limit the amount of sodium you ingest to 1,000 milligrams per day. You can also try using natural diuretics, which include lemon water and grapefruit. But most important, make sure you drink eight glasses or 2 liters of fluid a day (not just water but juices, food and fruits also count toward the total). Paradoxically, the more water you drink, the less your body will retain [source: Everson].
8.Medications
Frustratingly, many of the drugs prescribed to treat conditions related to obesity, such as high blood pressure and diabetes, may actually pack on some pounds. So do many of the drugs prescribed for depression and mental disorders [source: Storrs].
Of course you should take all necessary medications. But speak to your physician if you believe your medicine is causing you to burst your seams. There may be alternatives that are gentler on your body.
Here are four pharmaceuticals that are associated with weight gain [source: Storrs]:
Prozac (fluoxetine). People on Prozac initially lose weight. But over a long time — more than 30 weeks, according to one study – they begin to gain again. People develop a tolerance for the fullness effect promoted by Prozac.
Depakote (valproic acid). This drug, used to treat bipolar disorders and prevent seizures, affects the proteins associated with metabolism and appetite. In one study, 44 percent of women and 24 percent of men gained 11 pounds (5 kilograms) over a year on this drug.
Deltasone (prednisone). An oral corticosteroid, it's associated with weight gain in 60 to 80 percent of users.
Antihistamines, like Allegra and Zyrtec. The histamine blockers disrupt the enzymes that regulate food consumption.
On the positive side, birth control pills do not cause weight gain, with the exception of the injectable progestin depot medroxyprogesterone acetate (DMPA).
7.Hypothyroidism
Your butterfly-shaped thyroid gland sits in the front of your neck. This little-heralded gland churns out hormones that regulate your metabolism. If it shoots out too many in your bloodstream, you may develop hyperthyroidism. If it shoots out too few hormones, you may get hypothyroidism. The latter is the more common of the two problems. Side effects include sluggishness, feelings of coldness, slower heart rate, feelings of exhaustion and depression, a swelling of the neck and weight gain. With both hypothyroidism and hyperthyroidism, your hair may fall out [source: WebMD].
Women, especially those over 60, are more likely get hypothyroidism than men — and it tends to run in families. It is often caused by Hashimoto's disease, an autoimmune disorder where the body attacks the thyroid gland. A simple blood test measuring the amount of TSH, or thyroid stimulating hormone, in your system can diagnose whether you suffer from a thyroid condition. If you have any reason to believe you do, ask your physician to conduct this blood test, which is fairly common. Look also at your neck in the mirror as you tip your head back and swallow some water. If you see a bulge below the Adam's apple, you might have a thyroid condition [source: WebMD].
6.Constipation
You're exercising. Carefully watching what you eat. Yet the scale has made a sudden jump upward, and your pants are a bit tight. How can this be? One thing you can check is your gut — digestive issues could be the cause. Some people have a bowel action every few hours, others just once a day. Whatever's your normal pattern, if it's not happening anymore, a backed-up system may be the reason behind those suddenly tight jeans [source: Cohen].
Irregularity may be due to a variety of factors. You may be dehydrated, not taking in enough fiber or lack the proper amount of good flora in your stomach. The easiest way to stay hydrated is to drink more fluids, but fruits contain a fair amount of water, as do (surprisingly) some meats like hamburger and chicken breasts [source: Davis].
Load up on fiber by noshing on such foods as beans, bran and fruit. You also may want to take probiotics, which are live bacteria and yeasts that are helpful to your digestive system. Probiotics come in pill form and are also added to various types of foods [source: DiLonardo].
5.Cushing's Syndrome
Sometimes your excess poundage really is due to a medical condition. One of the top culprits is Cushing's syndrome. The rare disease was first described in 1932 by Dr. Harvey Cushing, an American neurosurgeon who helped pioneer brain surgery [source: Nordqvist].
The syndrome named after Cushing is a complex hormonal condition where the body is flooded with far too much cortisol, the body's main stress hormone. This may occur because of a disorder (for instance a tumor in the pituitary gland), or else you've been taking a lot of steroid-based medications (like the ones prescribed for asthma). In normal amounts, cortisol, produced by the adrenal glands, works to regulate your glucose levels and suppress the immune system.
But get too much coursing through your system, and you may end up with thin skin, bruises, high blood pressure, osteoporosis, diabetes, weakness, a puffy face, fat on your neck and shoulders and, yes, weight gain. Indeed, accelerated weight gain is the main characteristic of Cushing's syndrome
If untreated, Cushing's syndrome can lead to death. However, there are several remedies available, from slowly reducing the amount of corticosteroids taken to surgery (in the case of a tumor) [source: Nordqvist].
4.Polycystic Ovary Syndrome (PCOS)
Another medical condition that could be behind an unexplained weight gain is polycystic ovary syndrome, or PCOS. A hormonal disorder that affects women, PCOS is relatively common among females in their child-bearing years, striking between 1 in 10 and 1 in 20 women in the U.S. alone [source: Women's Health].
The disease causes women to develop many small cysts on their ovaries. The cysts, in turn, wreak havoc with their hormones, causing an increase in the male hormone androgen. That hormonal imbalance results in acne, a messed-up menstrual cycle and excess body hair. It also causes women to become resistant to insulin, which regulates blood sugar, and thus may result in them getting fatter. Unfortunately, these extra pounds tend to pile on in the belly area, leaving those affected more susceptible to heart issues.
PCOS is the most common cause of female infertility. The condition may be genetic, as women with PCOS are more likely to have a mother and sister with PCOS, too. So if you're a woman whose weight has surged and some of your relatives have PCOS, get checked for it yourself [source: Women's Health].
3.Lack of Sleep
Several studies show some pretty strong connections between lack of sleep and weight gain. One such study, the Mayo Clinic reports, showed that women who got less than six hours of sleep (or more than nine) were more likely to pack on a whopping 11 pounds (5 kilograms) than females nodding off for seven hours nightly. Another study on the subject found men who lacked adequate Z's took in more calories each day and preferred high-calorie foods.
So what's sleep got to do with it? One somewhat obvious connection is the longer you're awake, the more time you have to get hungry and eat. Some posit that if you're tired from a lack of sleep, you're less likely to be active and burn calories. Others say the amount of sleep you get each night is tied to the hormones regulating hunger; if you mess them up, your appetite becomes heightened [source: Hensrud]. The easy answer is to simply get a good night's sleep — seven or eight hours — every night. And why not? It sure feels great!
2.Stress
At first glance, you might think just the opposite: Stress will cause you to lose weight. You might have a friend who was stressed from a pending divorce and dropped 20 pounds (9 kilograms), or a sibling anxious about a job loss who suddenly lost his appetite and became too thin. But stress is actually the reason behind a lot of people's weight gains.
First, adrenaline floods our bodies when we're anxious and stressed out, preparing us for battle (adrenaline is known as the "fight-or-flight" hormone). That rush of adrenaline is followed by a cascade of cortisol, known as the "stress hormone."
Cortisol tells our bodies to eat, because in early human history, that extra energy from food was necessary for activities like running and physically fighting. Nowadays, our stress might come from not having enough money to pay bills rather than facing a wild animal, yet our bodies are still programmed to store fat when we're anxious. Cortisol is also the culprit behind emotional eating, that mindless shoveling of food down when we're stressed, and behind our craving for "comfort foods" like ice cream and chips when we're feeling low [source: Greenberg].
As for those people who lose weight from stress, it's likely that they've lost interest in eating or are fidgeting a lot from anxiety, which burns calories.
1.Genes
Many an overweight person has claimed that the extra poundage is all due to their genes. There might be something to such an assertion. Researchers studying mice discovered a genetic mutation in the MRAP2 gene that didn't allow them to burn off calories from fat; this same genetic mutation was found in obese humans. Initially, the mice's genetic mutation caused them to eat less than the norm. However, despite the reduced calories, the mice gained about twice the poundage of normal mice. Eventually the mice's appetites returned, and they ate a typical diet — yet still gained more weight than mice without that mutation. Why? The bodies of the mice with the genetic mutation were storing fat, not burning it for fuel. In a study of 500 obese people, scientists found a similar situation with the human version of the MRAP2 gene [source: Sifferlin].
Keep in mind, though, that scientists have identified only about eight genetic mutations that cause obesity in humans. And these mutations are considered to cause less than 5 percent of all of the cases of obesity in society [source: Sifferlin]. So while your portly physique may be in your genes, it's more likely just in your jeans.