1 You’ll lose a pound for every 3,500 calories you cut.

“Because 3,500 calories equals about 1 pound (0.45 kilogram) of fat, you need to burn 3,500 calories more than you take in to lose 1 pound,” explains the Mayo Clinic Web site. “So if you cut 500 calories from your typical diet each day, you’d lose about 1 pound a week (500 calories x 7 days = 3,500 calories).”

If only it were that simple.

If you burn 500 calories more than you take in every day, you will lose about a pound a week. But once you’ve lost roughly 10 percent of your body weight, cutting 500 calories a day isn’t enough to keep losing a pound a week because your body–afraid of starving–starts to burn fewer calories. (1)

“The body becomes a more efficient engine,” explains Rudolph Leibel, co-director of the New York Obesity Research Center at Columbia University. “It’s gone from being a Cadillac to a motorcycle. It’s getting more miles per gallon, and it’s a smaller vehicle.”

What can help? Move more to burn more calories. And do strength training to build muscle (which burns more calories than fat).

2 Too much sugar is the main cause of diabetes.
Diabetes is defined as too much sugar in the blood, so it’s reasonable that people would assume that eating too much sugar is the culprit. And it likely is a culprit.

For example, women who drink at least one sugar-sweetened soft drink or fruit punch a day have nearly twice the risk of diabetes over four years as women who drink less than one a month. (2) But it would be a mistake to think that sugar or soft drinks are the entire ballgame. Among other players:

* Weight & exercise. More than 80 percent of people with diabetes are overweight or obese. In a landmark study, weight loss cut the risk of diabetes by more than half in people who had pre-diabetes, and the average weight loss was only 9 pounds after three years. (3) The participants also boosted their exercise to 2 1/2 hours of brisk walking a week, but weight loss mattered more.

* Refined Carbs. People who eat more white potatoes have a higher risk of diabetes. (4) And people who eat more whole grains have a lower risk. (5) The fiber, magnesium, or chromium in whole grains may make a difference.

* Trans Fats. Women who eat more trans fat have a 30 percent higher risk of diabetes, while those who eat the most polyunsaturated fats have a 25 percent lower risk. (6)

* Meat & iron. People who eat about one serving a day of red meat have a 22 percent higher risk of diabetes than those who eat about one serving a week. (7) The heme iron in red meat may damage the pancreas, which produces insulin. And nitrites in hot dogs, bacon, and lunch meats could explain why men who eat processed meats at least five times a week have a 46 percent higher risk of diabetes than men who eat them less than once a month. (8)

“Apart from obesity, the greatest risk for diabetes is not just the huge amount of sugar, but the displacement of beneficial whole grains by the large amount of refined starch in the American diet,” explains Walter Willett, chair of the department of nutrition at the Harvard School of Public Health in Boston.

3 Sandwiches are lighter fare than entrees.

“I’m not that hungry,” you may think. “I’ll just have a sandwich.” Watch out. At many sit-down restaurants, the sandwiches have as many calories as the entrees. Take The Cheesecake Factory (one of the WORST places to eat in the country).

Its Chicken Salad, Grilled Chicken & Avocado Club, Chicken Parmesan, and Crabcake sandwiches each has 1,100 to 1,500 calories without the fries or green salad that comes on the side. That’s about as many calories as you’d get from most Cheesecake Factory steaks, chops, or even some chicken dishes.

And sandwiches range from 600 to 1,000 calories at Panera and from 500 to 700 calories at Au Bon Pain.

Sandwiches are no longer a shmear of tuna or egg salad on two thin slices of bread that people used to buy at the local lunch counter. They likely come with supersize rolls (or wraps), cheese, and dressings or spreads. Today’s sandwiches typically weigh three-quarters of a pound.

Want something light? Eat half a sandwich … and skip the fries.

4 Fruits & vegetables prevent most cancers.

“Eating vegetables doesn’t stop cancer,” declared the headline in The New York Times in April.

That’s a bit of an exaggeration, given that the study cited by The Times–which tracked 335,000 women and 140,000 men in 10 European countries for nine years–did find that people who ate more vegetables and fruit had a 3 percent lower risk of “all cancers” added together (which doesn’t necessarily apply to each individual cancer). (9)

And among those in the study at high risk of cancer due to smoking, cancer risk was 10 percent lower in heavy drinkers who ate the most vegetables. That makes sense, since earlier studies suggested that fruits and vegetables might help prevent cancers of the mouth, throat, larynx, esophagus, lung, and stomach. All are more likely in people who smoke and/or drink.

But researchers don’t have good evidence that fruits and vegetables can lower the risk of breast, prostate, colon, and most other cancers. So, can you dispense with the salads, stir-fries, and fruits-and-vegetables-as-snacks? On the contrary, they appear to lower the risk of heart disease and stroke. (10)

What’s more, their low calorie density means that they can help keep off unwanted pounds. And that’s critical because being overweight or obese does raise the risk of cancers of the breast, colon, kidney, uterus, and esophagus.

“The bottom line is to eat plenty of fruits and vegetables because the health benefits are substantial,” says Harvard’s Walter Willett. “But for cancer prevention, it’s much more important to avoid smoking and to stay lean and active.”

5 Mediterranean cuisine is good for you.

What researchers call a “Mediterranean diet” is indeed good for your heart and may even lower your risk of cancer. For example, in a study that tracked roughly 75,000 women for 20 years, those with a high Mediterranean diet score had a 30 percent lower risk of heart disease and a 13 percent lower risk of stroke. (11)

But a Mediterranean diet isn’t the pizza or lasagna you’d get at an Italian restaurant. “None of the current Mediterranean-type cuisines served in U.S. restaurants that come to mind are consistent with how scientists define a Mediterranean diet,” says Alice Lichtenstein of Tufts University in Boston.

Most Italian restaurant dishes are loaded with cheese, meat, and white pasta or bread. Greek restaurants are heavy on the lamb, beef, white rice, white bread, and potatoes.

In contrast, researchers typically came up with Mediterranean diet scores by giving people one point each for higher-than-average intakes of vegetables (excluding potatoes), fruits, nuts, whole grains, legumes, and fish. People also got one point for each serving of alcohol, for eating at least as much monounsaturated as saturated fat, and for a less-than-average intake of red and processed meats.

“I’m sure you can find something that fits with a scientist’s view of the Mediterranean diet in most restaurants,” says Lichtenstein. “But it’s more the exception than the rule.”

The Mediterranean diet gained fame when the Seven Countries Study found a low risk of heart disease on the Greek island of Crete in the 1960s. But studies describing the diet on Crete don’t mention whole grains or nuts (and do mention that white potatoes were a staple). (12)

“Scientists have defined a Mediterranean diet as whatever they thought would be an optimal dietary pattern,” says Lichtenstein.

The answer, she suggests, is to forget labels. “It would be better to talk about fruits, vegetables, fish, beans, whole grains, and other foods rather than a Mediterranean diet.”

6 You only need 20 minutes of exercise three days a week.

You can’t blame people for being confused about how much exercise is enough. Years ago, experts promised that at least 20 minutes of aerobic exercise three times a week was enough for cardiovascular fitness. (13)

These days, the Centers for Disease Control and Prevention (CDC) recommends at least 150 minutes a week of brisk walking (or equivalent activity). Meanwhile, the National Academy of Sciences recommends at least 60 minutes a day.

“It’s clear from many studies that 30 minutes of brisk walking five days a week is sufficient to lower the risk of many chronic diseases, such as heart disease, Type 2 diabetes, and certain types of cancer,” says I-Min Lee of the Harvard School of Public Health. “But it might not be sufficient to control our weight, given the high number of calories we take in.”

In Lee’s recent study, women who gained less than 5 pounds over 13 years were active for about an hour a day. (14) “Most were walking,” she explains. “If you do something more vigorous like running or jogging, swimming laps, or playing tennis, you can do 30 minutes a day.”

Don’t have an hour? Squeeze in a brisk 10-minute walk while you’re on the cell phone. Use a treadmill or stationary bike while you watch TV or use your laptop computer. Anything is better than nothing. “I don’t want people to get discouraged and say ‘I can’t do the hour a day so therefore I’m not going to be physically active,’” says Lee. “Someone who gets 30 minutes a day of exercise is better off than someone who doesn’t.”

7 Aerobic exercise is enough.

We know we’re supposed to get up off the couch and walk, run, bike, dance, swim, play tennis, whatever. But many people don’t realize that aerobic exercise is just part of the equation.

The CDC recommends “muscle-strengthening activities on 2 or more days a week that work all major muscle groups (legs, hips, back, abdomen, chest, shoulders, and arms).”

That means exercising against a resistance, explains Ben Hurley, a professor of kinesiology at the University of Maryland at College Park (and husband of Nutrition Action’s Jayne Hurley).

“The resistance could come from lifting weights or from your own body weight–such as doing push ups or sliding your back up and down a wall from a squat to a standing position,” notes Hurley.

Why do you need to strengthen muscles? “Without strength training, you start to lose muscle at age 40 if you’re a woman and in your 50s if you’re a man,” says Hurley.

You also lose bone as you age. “The average postmenopausal woman loses about 1 percent of her bone mineral density each year,” he explains. Strength training can stem the loss of bone and can rebuild some lost muscle. (15,16) “The earlier you start, the better,” says Hurley. “But there is no age limit for increasing strength.”

His advice: “You should be able to do at least 8 and no more than 15 repetitions.” If you can do more than 15, the load isn’t heavy enough to build muscle and preserve bone.

8 Food poisoning is just a temporary nuisance.

A bout of food poisoning is bad enough. No one wants to go through the gut-wrenching vomiting and diarrhea that seems endless. But most people assume that they’ll get over their food poisoning in a matter of hours or, at most, days.

Not always. In a small percentage of cases, food poisoning can lead to long-term consequences. (17)

Among them:

* Guillain-Barre syndrome. The terrifying disease starts as tingling in the arms and legs and progresses to paralysis that can last for months.

* Reactive arthritis. It’s an inflammation of the joints that’s triggered by an infection, and it can last for years.

* Kidney or nerve damage. E. coli O157:H7 is the bacterium that contaminated Jack in the Box hamburgers in 1993 and fresh spinach in 2006. A small number of victims end up with permanent kidney or nerve damage, and some die.

9 Low-fat foods are best for your heart.

Despite what many people think, “low fat” is not a yardstick that measures a food’s impact on your risk of heart disease.

“Initially, when the nutrition community focused on low-fat foods, they were thinking of replacing full-fat dairy and meat, which have a fair amount of saturated fat,” explains Tufts University’s Alice Lichtenstein. “But the concept of low fat got distorted.”

Some people assumed that they wouldn’t gain weight if they ate low-fat cakes, cookies, and ice cream. “Some people ended up eating all low-fat foods with abandon, and they gained weight,” says Lichtenstein. “But low fat doesn’t always mean low calorie.”

What’s more, foods that are rich in unsaturated fats–like fatty fish, nuts, avocado, and most oils (like canola, soy, and olive)–protect your heart. “If you squeeze out the healthy fats by eating too many sugars and refined grains, that’s not good because triglycerides go up and HDL cholesterol goes down,” says Lichtenstein.

What’s the healthiest diet? It’s a mix of some low-fat foods (vegetables, fruit, low-fat dairy, lower-fat poultry and meat) and some fattier foods (oils, fish, nuts, avocado), with surprisingly little room for carbs like breads, rice, pasta, potatoes, and sweets.

10 The signs of a heart attack are the same in men and women.

We’ve all seen what a heart attack looks like in movies and on TV. A man clutches his chest in severe pain and (in some cases) keels over. That’s not how most heart attacks happen. They’re most likely to start slowly with milder pain in the chest.

And instead of chest pain, some people report:
* Pressure, squeezing, or a sense of fullness in the chest. It usually lasts more than a few minutes, or it may go away and return.
* Discomfort or pain in one or both arms, the back, neck, jaw, or stomach.
* Shortness of breath.
* Other signs like breaking out in a cold sweat, nausea, or lightheadedness.

Women are more likely than men to experience nausea or vomiting, shortness of breath, or pain in the back or jaw.
In any case, the bottom line is the same for men and women: don’t wait more than 5 minutes before calling 9-1-1. (Don’t drive to the hospital yourself. You can get life-saving treatment in an ambulance, and you get there quicker.)

(1) Am. J. Clin. Nutr. 88: 906, 2008.

(2) JAMA 292: 927, 2004.

(3) N. Eng. J. Med. 346: 393, 2002.

(4) Am. J. Clin. Nutr. 83: 284, 2006.

(5) Am. J. Clin. Nutr. 76: 535, 2002.

(6) Am. J. Clin. Nutr. 73: 1019, 2001.

(7) Arch. Intern. Med. 164: 2235, 2004.

(8) Diabetes Care 25: 417, 2002.

(9) J. Natl. Cancer Inst. 102: 1, 2010.

(10) J. Natl. Cancer Inst. 96: 1577, 2004.

(11) Circulation 119: 1093, 2009.

(12) Am. J. Clin. Nutr. 49: 889, 1989.

(13) Med. Sci. Sports Exer. 10: vii, 1978.

From CSPI