Losing weight is simple math. If you cut 3,500 calories out of your diet in the course of a week without reducing your daily activity, you can say goodbye to one whole pound of fat. Yes, I know reading that sentence is easier than actually doing it, so I’m ready to give you two tricks to make the job easier.

First, cut your calories in small increments — 50 here, 100 there — rather than in one big lump. Second, instead of giving up foods you really love (and feeling deprived), switch to low-fat versions. This article tells you how to accomplish both.

I’ve included some brand-name products just so that you can compare different versions made by the same companies.

• Switching to Low-Fat or No-Fat Dairy Products

Milk and milk products are the best source for the calcium that keeps bones strong. But these same products may also be high in cholesterol, saturated fat, and calories. You can reduce all three by choosing a low- or no-fat milk product.

For example, a cup of whole milk has 150 calories, but a cup of skim milk has only 85. One slice of regular Kraft American cheese has 60 calories, but one slice of Kraft Free American cheese has only 30. A sandwich made with three slices of cheese is 90 calories lighter if the cheese is “free.”

• Substituting Sugar Substitutes

Coffee has no calories, but every teaspoon of sugar you stir into your cup has 15 big ones. Multiply that by four (1 teaspoon each in four cups of coffee), and your naturally no-cal beverage can add 60 calories a day to your diet. Sixty calories a day times seven days a week, and yipes, that’s 420 calories!

That’s about as much as you’d get from four or five medium slices of unbuttered toast or five medium apples. So is this a good time to mention that one packet of sugar substitute has absolutely zero calories? I thought so.

• Serving Stew Instead of Steak

No matter how you slice it, red meat is red meat — cholesterol, saturated fats, and all. But if you stew your beef or lamb or pork rather than broiling or roasting it, you can skim off a bunch of high-calorie fat. Just make the stew and then stick it in the fridge for a couple of hours until a layer of fat hardens on top.

Spoon it off: Every tablespoon of pure fat subtracts 100 calories from dinner. And, yes, you can also cut off all visible fat before preparing the meat. Same 100 calories per tablespoon of fat.

• Choosing Low-Fat Desserts

Who says you have to suffer to cut calories? Not me. One half cup of Häagen- Dazs chocolate ice cream has 270 calories. One half cup of Häagen-Dazs nofat chocolate sorbet has 140 calories. Believe me: Switching from the first to the second is no problem. If you’re a true chocoholic, you’ll send me valentines for this suggestion.

• Peeling the Poultry

Most of the fat in poultry is in the skin. A fried chicken breast with skin has 217 calories; without the skin, it has only 160. Half a roasted duck (with skin) has a whopping 1,287 calories; without skin, it’s only 444.

Even if you have a fried chicken breast every night for a week (which you would never, ever do), you can save 399 calories by taking the skin off before cooking the bird.

Share seven skinless half-ducks with a friend, and you each save 2,950 calories a week by removing the skin. Wow. That’s practically a pound right there.

• Not Oiling the Salad

True, salad can be a low-fat, low-calorie meal. Throw in some breast of chicken and a couple of no-fat croutons or cheese cubes, and it’s still mostly crunch. But the dressing can do you in.

For example, two tablespoons of Wishbone Italian Dressing or one tablespoon of Hellmann’s regular “real mayonnaise” have 100 calories. What to do?

Ah, c’mon, you know the answer: Switch. Two tablespoons of Wishbone Fat Free Italian dressing add just 15 — count ’em, 15! — calories.

One tablespoon of Hellmann’s Light cuts the calorie count in half, to 50 calories. Have salad once a day for a week, and you can save 595 calories with fat-free rather than regular salad dressing or save 525 calories with low-fat mayonnaise rather than regular.

Or as University of Maine nutrition guru Alfred Bushway suggests, “Using a tablespoon of balsamic vinegar instead is even better.” Neat. Don’t oil your pots and pans, either.

Bake with parchment paper instead of greasing the pan. Sauté with natural juices in nonstick pans. Every tablespoon of fat you don’t use means approximately 100 fewer calories in the dish.

• Making One-Slice Sandwiches

Depending on the brand, one slice of bread in your daily luncheon sandwich may have anywhere from 65 to 120 calories. Eliminating one slice and serving your sandwich open-faced can cut up to 840 calories from your weekly total. And you know that making that one slice whole wheat adds dietary fiber to your menu, right? Just asking.

• Eliminating the High-Fat Ingredient

A bacon, lettuce, and tomato sandwich usually comes with three strips of bacon, each one worth 100 calories. Leave off one strip and save 100 calories. Leave off two, save 200 calories. Leave off three, save 300 calories — and enjoy your lettuce and tomato sandwich with low-fat mayonnaise.

Here are some other ways to eliminate fat calories:

• Making spaghetti sauce without olive oil (100 calories a tablespoon)
• Making split pea soup without ham (55 to 90 calories an ounce)
• Making cream sauces with skim milk instead of cream (470 calories per cup for the cream; 85 to 90 calories for the skim milk)

• Seasoning the Veggies instead of Drowning Them in Butter

This one’s a no-brainer. Season your vegetables with herbs instead of greasing them, and you save 100 calories for every unused tablespoon of butter, margarine, or oil. Think dill on the potatoes, chives on the corn, oregano on the green beans — whatever catches your imagination.

• Washing the Chopped Meat

Yes, you read that right. Heat a teapot of water. Put the chopped meat in a pan and cook it until it browns. Pour off the fat, turn the meat into a strainer, and pour a cup of hot water over it. Repeat two times. Every tablespoon of fat that melts or drains from the meat saves you 100 calories, plus cholesterol and saturated fat. Use the defatted meat in spaghetti sauce.