When we’re young, our lean body mass is considerable. We are more active, and the level of energy necessary to maintain all that muscle is higher.

As we age, our need for muscle mass usually declines, and the energy necessary to keep everything working declines in proportion. The energy we need to keep functioning is called the basal metabolic rate (BMR), and it declines normally with age.

If everything remained proportional, our weight would decline as well because our fat content would be maintained at a constant percentage, about 22 percent for women and 18 percent for men.

For example, if you’re a man and your lean body mass was 140 pounds at age twenty when you were very active, you simply don’t require that same lean body mass at age fifty even if you jog 10 miles weekly. Nor should your percentage of body fat be any different.

Unfortunately, in our society where over 50 percent of adults are overweight, the man in my illustration at age twenty is much more likely to weigh over 175 pounds, and possibly as high as 190 at age forty and more at age sixty. Our lifestyle goes against us.

Eating habits are usually established in the teenage years, and our activity levels drop off as we enter the workforce after school. Therefore, energy expenditure from exercise and work declines while we consume the same food calories or more.

We usually consume more calories as we get older; for example, meals and snacks become longer, more regular, and are likely to be enhanced with alcohol or soft drinks.

Consequently, people usually gain weight as they get older, and it’s very, very rare that their body fat percentage declines. Indeed, percentage of body fat usually increases as people get older. So, how do you deal with your weight if you’ve got high blood pressure?

First, let’s decide whether or not you’re overweight. Overweight is an overworked term; it implies that there is some arbitrary standard that tells precisely how much you should weigh.

If you’re an average man, in good shape, you’ll have 13 to 15 percent body fat. You likely get some active exercise, some tennis or jogging, for example, and would be able to run a mile in under eight and a half minutes.

If you’re an average woman in good shape, you’ll have 20 to 22 percent body fat. Like the average male, you probably get moderate exercise and can run a mile (or equivalent) in under eight and a half minutes without difficulty.

By comparison, if you were a regular distance runner, I would expect you to come in at 8 or 9 percent body fat and wouldn’t be surprised at 6 percent for serious marathoners.

If you were a fast-moving tennis player, about 13 percent body fat would be normal for men, 15 percent for women. Percentage of body fat is proportionate to physical need up to a point; fat beyond that percentage is just too much fat.

And too much fat imposes stress on your heart, other organs, joints, and in many people causes high blood pressure. If it’s possible for you to have your percentage of body fat precisely determined, by all means have it done, because you can determine very accurately how much weight, if any, you should lose.

The best and most precise method is weighing both in and out of water. It requires sophisticated equipment, however, and can’t be done at home, or even in the doctor’s office. Actually, you can weigh yourself quite accurately in the water if you are willing to get a spring-type bathroom scale wet and have the use of a pool.

All you’ve got to do is weigh yourself (in bathing suit) on the ground; then take the scale into the pool and do the same thing with as little of you out of the water as possible and after breathing out.

Simply duck your head under to read the numbers on the scale and hold as little breath as possible. It’s a lot of trouble, but it works. Or get in a swimming pool, curl into a ball, and exhale as you hold your head under water.

If you slowly sink, you’re probably about right. Sink quickly, and you’re better off because you’ve got even less fat. The more easily you float, the greater your excess fat.

Body measurements are another approach. Stand naked in front of the mirror and observe the following: With feet and knees together facing a mirror, do you see a crack of light above your knees and below your crotch? Can you easily find your hip bones?

Turn your side to the mirror and exhale. Are your stomach and abdomen flat and your buttocks firm? If not, start working out regularly. Tape measure your hip-to-waist ratio. Measure around your hips and waist, and divide the waist measurement by the hip measurement.

The ratio for women should be 0.8 or less, for men, 0.9 or less. If the ratio is one or more, you are excessively fat and rapidly developing heart disease. Hold your arm out and grip below the biceps. It should be firm and not droop.

If it droops and isn’t firm, you need more exercise. You can actually purchase, or in some places use for a fee, a scale that uses sound waves to estimate your body fat content.

The process is simple: You stand on the scale for a few minutes and get your results. Your body evolved to survive in a world of scarcity. When there’s excess available, it’s very good at storing those extra calories as fat.

Fat stores calories efficiently. It conserves 9 calories per gram; that’s about 3,500 calories for each pound, and it’s pliable at body temperature and requires no water for storage. Carbohydrates, on the other hand, are solid at room temperature and must be dissolved in water to be used by the body.

For every pound of carbohydrate, the body requires at least 3 pounds of water. When a carbohydrate is “hydrated,” 1 pound, yielding 1,800 calories, becomes 4 pounds of total weight—that’s only 450 calories per pound in contrast to fat at 3,500 calories per pound.

Aside from sheer bulk, if calories were stored as carbohydrates, the extra water would elevate blood pressure—one more reason why the body stores its reserve calories as fat.

Excess weight comes from consuming more calories than we burn. But beyond that basic fact, there are several other factors that determine why some people are heavier than others on seemingly the same food intake.

First, some people have a lower basal metabolism than others, and it’s lowest in overweight people. Their extra fat acts as an insulator; they don’t lose as much heat to the environment, for example.

Basal metabolism is the daily calorie expenditure needed to stay alive; the energy you would expend if you stayed in bed all day. Second, there’s the set point theory. This theory says that our brain accepts a level of body fat as “normal” and strives to maintain that level, which becomes a set point.

Only by changing this set point can we establish a lower, healthier weight. Third, or perhaps as part of the first two concepts, the cell size, cell number hypothesis emerged.

In this concept, during the first two years of life, the body develops a certain number of cells for fat storage. Some individuals develop more fat cells than others, which makes it easier for them to gain weight.

So, if we combine all these concepts, we can conclude that some people have a naturally low metabolism, or develop a high set point that gives them a certain fat level, or start out in life with an excessive number of fat cells.

They may store fat either as lots of small fat cells or as fewer, but larger fat cells. Weight loss is the same no matter what the storage form and no matter what the set point.

You’ve got to burn more calories than you consume and keep doing that for a long time. Exercise is the only thing we know that will produce lean muscle. Suppose you’ve got to drop a total of 10 pounds of fat.

At 3,500 calories per pound, that means you’ve got to create a deficit of 35,000 calories. You can consume very few calories, even starve, for a day or two, but you can’t do it for a prolonged period.

You’ll need to establish an average daily caloric intake. If you follow the plan, you’ll consume 1,000 to 1,200 calories daily. Well, 2,200 minus 1,000 leaves a daily deficit of 1,200.

That means you’ll lose 1 pound every three days if you’re true to yourself. Or, put another way, it’ll take thirty days to lose the 10 pounds. Weight doesn’t come off steadily, though.

First, you’ll drop some stored carbohydrate and extra fluid, which means a big water loss. In fact, I’ve seen many people lose 5 percent of their body weight in the first five days.

But your body will restore lost carbohydrate and water even while you’re still losing weight. People who temporarily regain water and carbohydrate weight often despair because they seem to be gaining, not losing.

I assure you, they are losing weight; in the clinic we precisely measure fat loss and it would still be declining. There will be times when you seem to gain weight.

But, if you’re true to yourself and stick with your program, you can lose 1 to 2 pounds each week over a long period of time and gain a whole new outlook on life. It is absolutely essential that you do a personal assessment to see if you are fit or fat.

Strive to get your body into shape so that your general assessment is realistic. If you need to lose some weight, diet sensibly and maintain your sodium-potassium balance at the same time. Set realistic goals so you know where you’re going and how you’re getting there.