What follows are the rules to leanness that really matter. And really work!

Pretend you are a tailor.  Measure everyting - your neck, chest, waist, arms, thighs, calves.  Write it all down, and put it someplace where you  will have to look at it every day.  Record your weight too, although that is less important.

Your goal:  Maintain or reduce the size of your waist while increasing the size of everything else. Repeat your measurements every 4 weeks.

To change your weight, follow the 15/500 rule.  Making radical changes to your diet -  starving yourself to lose weight or stuffing yourself to gain -  is futile. If you are trying to lose weight, you will slow your metabolism to a crawl.  If you are trying to gain, the excess calories will include a lot of fat.  Here is a more sensible strategy.

To lose weight:  Cut your daily food intake by a maximum of 15 percent or 500  calories, whichever is less. 
        
To gain weight:  Increase your daily intake -  EVERY DAY - by 15 percent or 500 calories, whichever is less.

You Must Eat Fat

Fat still occupies that tiny prison cell at the tip of the Food Guide Pyramid, but its health benefits are hugely underrated. 

A diet with 21 percent of its calories from  monounsaturated fat reduces your risk of cardiovascular disease by 25 percent, according to the Penn State University study.  And research has shown that men eating a diet with high fat have higher testosterone that those eating less fat.  So chomp on those macadamia nuts and drench your salad with olive oil.  Not only will your enjoy your food more, you will live longer and have more sex.

Meat Is Muscle

The best muscle-building diet includes beef, pork, poultry, and fish.  The reason is simple:  Animal protein builds muscle better than soy or vegetable protein does.

How much protein you need is always debated, but it is generally believed that  you need 0.6 to 0.82 grams of protein per pound of body weight per day to build muscle during a strength-training program.  If you weigh 200 pounds, that means taking in 120 to 164 grams of protein each day.  Say you choose 150 grams as your daily goal.  Split it up so you eat 25 grams in each of six small meals.  Breakfast might be two eggs, milk, and oatmeal.  Lunch could be tuna a whole wheat. Grilled-chicken salad would be a good dinner.

You Need Carbohydrates (but the right kind)

Consumption of high fructose corn syrup and other sugary sweeteners has possibly done more to expand America's waistlines than anything else.  In fact, Americans consume twice as much sugar a day as they should.  But the carbohydrates in fruits, vegetables, and whole grains are crucial to your health, give you energy, and help you build and repair muscle after workouts.

How much is enough:  If your main goal is to be lean, try about 20 to 40  percent carbohydrate in your diet.

Eat Before You Lift

You increase muscle mass in two ways:  by building up muscles and by preventing them from breaking down.  If you eat some protein an hour or two before your workout, you will have more amino acids available to your muscles during exercise.  This prevents the muscle tissue from breaking down as much as it otherwise would.

You also need pre-exercise carbohydrates to ensure you will have enough energy during your workout.  Without this type of fuel, your muscles could break down the amino acids in your muscles for energy.

Here is an idea for a preworkout meal:  Make a small shake with juice or fruit, milk, yogurt, and/or a scoop of whey protein powder.  Fat and fiber slow digestion, so limit them before a workout.

Eat After You Lift

After a workout,  you want to eat some muscle building food containing both carbohydrates and protein. This is the one time of day when you benefit from eating fast-acting, easily digestible carbohydrates, such as white bread, instant rice, and baked potatoes.

Here is why:  After exercise, your muscles are more sensitive to insulin.  Insulin is the rapid-transit system for the protein and carbohydrates your muscles need for growth, repair, and fuel.  The faster you digest the carbohydrates you eat, the faster your body can put them to use.

The best post exercise meal:  Try a shake made with a meal-replacement powder containing protein and a fast-moving carbohydrate like maltodextrin.  Or try the shake described in the section above.

Stay Nutritionally Prepared

You are going to get hungry every 2 to 3 hours, guaranteed. So be prepared.  If you know you are going to be away from decent food, take some healthy snacks with you.  Nuts or a protein bar are compact and require no special preparation or refrigeration.  If you need to pack something more meal-like, try a sandwich on whole grain bread.  Keep apples in hand's reach everywhere you go. The pectin in apples will help to keep you full enough that you will not crave anything too far off your diet.

Eat Before You Go To Bed

If your are trying to build muscle while losing weight, you need some food right before sleep to keep your body from breaking down muscle tissue as you snooze.  Planning this snack will help you resist the temptation to eat high calorie or high carbohydrate food before midnight.

Take Notes

I have given you a lot of math here - 500 calories of this,  0.82 grams of that.  All of which is meaningless unless you know how much you actually consume.

For 1 day, try this:  Measure everything that you eat.  You will have to take out a measuring cup and see how much cereal you eat, count the slices or weigh the turkey breast that you put on your sandwich, add up the bananas and dried apricots and Kit Kat bars.

Now write it all down, and calculate the total.  Everyone knows that you are what you eat, but most of us have now idea how much.