One recent survey of Americans on body image found that more than half of all men and women would rather lose their job than gain an extra seventy-five pounds. And nearly 20 percent of the population would give up, or consider giving up, 20 IQ points to have the perfect body.

Obviously, weight and the way we are perceived is an important factor in our daily lives. It’s not surprising then that dieting is on the minds of so many people these days, particularly as people get on in their forties, when the metabolism begins to slow and the pounds begin to add up. So which diet is best? I’ll tell you.

First, let’s look at some of the big blockbuster diets that have appeared over the past decade or so—the South Beach Diet, the Atkins Diet, the Mediterranean Diet, and so on. Each one of these diets has simply incorporated a different method of teaching you about nutrition in order to get you to lose weight. Each one gives you something to focus on, a behavior to motivate you, which is great because, after all, to lose weight you have to change your thinking.

But if you look at the fundamentals, the underlying theme of each diet is calories. Whether you do Atkins, South Beach, or Dr. Phil, it’s really all about calories.

When reviewed carefully, most diets are really nothing more than low-calorie nutrition plans disguised by clever marketing gimmicks. Scientific-sounding “facts” and hocus-pocus “research” are just ornaments on the diet tree. Diet-plan marketers go to great lengths to explain how their diet can work for everyone, or claim that it is carbohydrate intake or fat intake—or whatever the bad intake of the day is—that’s the culprit.

However, the bottom line is that the only way to lose weight is to have a caloric deficit, which occurs only when you burn more calories than you consume.

The average American today consumes 300 more calories per day today than did the average American of 30 years ago. Today’s average American also burns 260 fewer calories each day due to increased automation, technology, and sedentary occupations. Put those numbers together, and it becomes rather obvious why America’s waistline is growing at an alarming rate.

Check Your BMI

The BMI can tell you if you are underweight, normal, overweight, or obese. Adults 20 years old and older can calculate their BMI with this formula:

BMI = your weight/pds divided by height/in x height/in x 703

You are UNDERWEIGHT, if your BMI is below 18.5.

You are of NORMAL WEIGHT, if your BMI is between 18.5 and 24.9.

You are OVERWEIGHT, if your BMI is between 25.0 and 29.9.

You are OBESE, if your BMI is 30.0 or more.

So here is Dr. Manny’s Freedom Diet. If you really want to lose weight, you have to do two things: eat fewer calories and burn more calories. This is not an optional “either/or” plan but an “and” plan. Of course, the calories you eat should be healthy calories. That’s all. Eat less. Exercise more. It really is that simple.

Fight obesity. Spread the word.

Exercise

People spend an enormous amount of time trying to find the perfect exercise, and while they’re doing that, their clock is ticking. Any physical activity is great, though the best kinds of exercise for you are those like walking, swimming, running, hiking, and skiing—all of which have a “global” impact on your body and mind.

Most important, you should stick to the exercise of your choice and do it regularly. If you adhere to those two principles, you’re going to burn calories, feel better, improve your metabolism, and benefit your health.

Any activity you do during the day—from climbing stairs, to housecleaning, to watching TV—will, of course, burn calories. But those activities don’t provide the necessary continuity, and I think the essence of getting into shape and having a good metabolism has to do with a continuity of exercise.

In other words, it’s better to burn 120 calories a day, seven days a week, doing your favorite exercise, for example, than to burn 800 calories doing the housework once a week. It’s the exercise regimen that has an impact on your health, not necessarily the intensity.

Burn, Baby, Burn

Estimated number of calories burned per minute based on an individual weighing about 150 pounds:

Sitting: 1

Talking on phone: 1

Sleeping: 1

Driving: 2

Housework: 3

Cooking: 3

Washing dishes: 3

Stretching: 4

Sex (active): 5

Walking (3 mph): 5

Calisthenics (moderate): 5

Ballroom dancing (fast): 6

Gardening: 6

Swimming (moderate): 7

Aerobics (low impact): 7

Hiking: 7

Jogging: 8

Stair step machine: 8

Bicycling (12 to 14 mph): 10

Basketball (full court): 12

Running (10 mph): 20

To easily calculate how many calories you burn in a day, go to www.healthstatus.com and click on “Calculators” then “Calories Burned.”

It is also very important to drink adequate amounts of fluid when you exercise. You need to drink about a half cup of water for every fifteen minutes of vigorous exercise. People think that muscle cramps during exercise are caused by a shortage of electrolytes, but that’s not true. You get muscle cramps because of water loss and dehydration. Drink that water!

Click here to check out Dr. Manny's book The Check List (Harper Collins, 2007), from which this article was excerpted.

Dr. Manny Alvarez is the managing editor of health news at FOXNews.com, and is a regular medical contributor on the FOX News Channel. He is chairman of the Department of Obstetrics and Gynecology and Reproductive Science at Hackensack University Medical Center in New Jersey. Additionally, Alvarez is Adjunct Professor of Obstetrics and Gynecology at New York University School of Medicine in New York City.

Dr. Manny Alvarez serves as Fox News Channel's senior managing health editor. He also serves as chairman of the department of obstetrics/gynecology and reproductive science at Hackensack University Medical Center in New Jersey. Click here for more information on Dr. Manny's work with Hackensack University Medical Center. Visit AskDrManny.com for more.