Some diet myths:

Are Negative Calories for Real? | New York Times Video

The Claim: You Burn More Fat by Exercising on an Empty Stomach

By ANAHAD O’CONNOR

THE FACTS For most people who exercise in the morning, there is no getting around the question: Eat and run? Or run and eat later?

Fitness experts will say that eating first provides fuel for a proper workout. But according to one common belief, exercising on an empty stomach forces the body to tap into its reserves, burning off calories stored as fat and providing a more efficient workout. So who is right?

According to researchers, there is no simple answer. One study that examined the claim directly in 1995 found that a group of people did burn more calories from fat on days when they exercised on an empty stomach than on days when they had a small breakfast first. But the researchers found that the difference was negligible, and other studies have shown that fewer calories are burned in the long run because the workouts are shorter.

A study published in 1999 in the journal Medicine and Science in Sports and Exercise had a group of people ride an exercise bike on two mornings: on one day after a small breakfast, and the other after eating nothing. The researchers found that when the subjects ate nothing, they became fatigued faster and stopped exercising about 30 minutes earlier.

Dr. David Prince, an assistant professor of rehabilitation medicine at the Albert Einstein College of Medicine of Yeshiva University in New York, said that when you exercise on an empty tank, your body burns through stored carbohydrates first, then protein, before it finally moves on to fat. In the meantime, he said, “you lower your blood sugar, causing ravenous hunger that in most people would lead them to eat much more than they would otherwise.”

His recommendation? A small piece of fruit, “just enough to give you energy for a more intense workout.”

THE BOTTOM LINE Exercising on an empty stomach burns slightly more fat but shortens your workout.

Birth Control Pills - Weight Gain - The Claim: The Pill Can Make You Put On Weight - New York Times

The Claim: The Pill Can Make You Put On Weight

By ANAHAD O’CONNOR

THE FACTS Quick weight gain may be among the birth-control pill’s most dreaded side effects. But how much does it really add to your waistline?

Last year, a group of researchers carried out what may be the most extensive study on the subject to date. Their conclusion: In most women, neither the pill nor the patch seems to add any pounds at all.

Of 44 previous studies that the researchers combined and analyzed, 3 found no difference between women who took hormonal contraceptives and those who took a placebo. The other studies looked at women taking different types and doses of hormonal contraception, and came to the same overall conclusion.

The claim may have had some truth many years ago, when the pill contained high levels of estrogen, which can cause water retention and increased appetite. Nowadays, most versions of the pill have only half the amount found in early versions.

Some studies have shown that while the pill may add a couple of pounds at first from water retention, the added weight disappears as the body adjusts to the hormones.

Another factor has nothing to do with the pill: most women start birth control as teenagers and continue it through their 20s, a period when women naturally tend to gain weight.

THE BOTTOM LINE The link between the pill and weight gain is exaggerated at best.

Muscle Turns to Fat if You Don’t Use It: FALSE!

Muscle and fat are two distinct tissues that don’t convert into each other. When you stop exercising, muscles shrink and allow for fats to slide into their place. People who stop exercising also tend to consume the same number of calories they did when they were working out, which means fewer calories out and probable weight gain. And since muscle mass increases the metabolic rate, less muscle means you’re more likely to put on fat weight if you’re eating more and exercising less. All three factors give the illusion of muscle turning to fat. The good news is moderate physical activity can prevent this from happening.

People Gain an Extra Five Pounds During the Holidays: FALSE!

Although it may feel like you’ve gained five pounds by the time New Year’s rolls around, most likely you haven’t. The average person gains just one to two pounds during the six-week year-end holiday period. In a recent study of 200 adults, participants gained an average of 1.05 pounds between early October and late February. Only 10% of the subjects gained more than five pounds. The biggest problem is that any weight you gain tends to stick around for good, despite those New Year’s resolutions you make. So make sure you watch the number of holiday goodies you consume.

A Cup of Green Tea Can Help You Lose Weight Faster: FALSE!

Lately, everyone’s touting the benefits of green tea, from improved digestion to better brain function. However, in many cases there is little scientific evidence to support the claims. For example, green tea is chock full of catechins, compounds with antioxidant properties that supposedly speed up the metabolism and help you burn off fat. Unfortunately, the levels of energy expenditure they generate are too small to promote any significant weight loss. On the plus side, one study showed that men who took a special green tea extract containing 690 milligrams of catechins – 20 times the amount in a typical cup of green tea – lost two pounds more than those who didn’t take the extract. So massive amounts of green tea extract might serve as a weight loss aid, but a cup or two a day isn’t going to make any significant difference.

The Claim: C.L.A. Supplements Can Help You Lose Weight - New York Times

By ANAHAD O’CONNOR

THE FACTS

It has been called a miracle pill, able to help you shed fat, lose weight and build muscle. It can be found in health food stores all over, but is C.L.A. — also known as conjugated linoleic acid — all it’s cracked up to be?

Discovered more than two decades ago, the substance is popular among dieters and body builders, and reportedly reduces body fat gain and enhances lean body mass. Over the years, a number of studies have found that C.L.A., unlike many other supplements, may actually help users trim fat. But it also carries side effects.

The most recent study was published this month in The American Journal of Clinical Nutrition. The report, a meta-analysis that pooled the results of more than a dozen randomized studies, found that people who took 3.2 grams of C.L.A. a day showed a drop in fat mass of about 0.2 pounds a week — or nearly a pound a month — compared with those given a placebo. The researchers, at the University of Wisconsin School of Medicine, concluded that the supplement “produces a modest loss in body fat in humans.”

But other studies have hinted at serious adverse health effects. Researchers have found that it can increase blood levels of C-reactive protein, lipoprotein and leptin — all of which can heighten the risk of heart disease. There is also some evidence that taking C.L.A. daily increases insulin resistance, a sign of impending Type 2 diabetes.

THE BOTTOM LINE

Studies have found that C.L.A. supplements can produce slight reductions in body fat, but that it may carry health risks.

That was very informative Julie! Thanks

if i try to workout on an empty stomach, i get so dizzy.!