The first thing you need to understand is that your
body has a weight control system controlled by your hypothalamus. Your
body weight is determined by a regulating mechanism known as a setpoint
(Leveille, 1985). Your setpoint is analogous to the thermostat in your
home. After setting the house thermostat at a certain temperature, say
72°, your furnace then shuts off when the house is warm and turns on
when the house cools off. The whole system is geared toward maintaining
72°. Your body works the same way in terms of body weight and metabolic
rate. Each of us has our own biologically determined setpoint for weight
and our body works to keep us at our particular setpoint, a process
known as homeostasis.
When you go below your setpoint (such as after a diet), your metabolic
rate naturally slows down, calories are burned more slowly to conserve
fuel, and you tend to gain weight until you return to your setpoint.
This is why diets so often fail, especially when it comes to maintaining
weight loss. Most diets, even the most outlandish and faddish, will
work in the short run given reasonable motivation on the part of the
dieter. But once you go below your setpoint, homeostasis sets in,
thereby lowering your metabolism and returning you to your setpoint.
This often occurs even if you are eating in moderation.
There is no magic way to
lose weight. Quick-weight-loss diets are not recommended, because in the
long run they simply do not work. Chronic dieting can also be hazardous
to your health. Men who perpetually diet were found to have
dramatically higher rates of heart disease and diabetes than men who
never or rarely diet. And individuals who have widely fluctuating
weights over long periods of time were found to have higher health risks
than those whose weight was steady, providing yet another reason not to
diet (Shapiro, 1997).
Thus the process of
dieting can be very discouraging and self-defeating. Diets only lower
your body weight; they usually do not lower your setpoint. In fact,
diets can sometimes actually raise your setpoint. Very-low-calorie diets
throw your system into a “starvation mode” and your body responds by
continually lowering your metabolic rate to compensate for the reduced
caloric intake. This is a primitive survival mechanism, a holdover from
ancient times when our ancestors routinely dealt with famine and
drought. To combat this, the human body developed a fail-safe mechanism.
When food was unavailable or in short supply for our forebears, their
bodies responded by lowering metabolism, thereby conserving body weight
and making the most of what food was available. This mechanism remains
with us. Our bodies respond to a diet as if it were a famine. And if you
continually diet or frequently start and stop diets, your body will
then reset your setpoint at even higher levels to guard against future
diets (which it interprets as starvation). Thus, continued dieting may
make you gain even more weight in the long run, which accounts for the
yo-yo effect.
Although dieters are told
that they will lose a pound for every 3,500-calorie reduction in their
diet, this turns out not to be true once their metabolic rate slows
down. As many a dieter can testify, the drop in resting metabolic rate
can be particularly frustrating. After the rapid weight losses that
occur during the initial three weeks or so of a rigorous diet, further
weight loss comes slowly. In one study (Bray, 1969), obese patients
whose food intake was reduced from 3,500 calories daily down to a
near-starvation 450 calories daily lost only 6 percent of their weight,
partly because their metabolic rates dropped about 15 percent. That is
why reducing your food intake by 3,500 calories may not reduce your
weight by one pound. And when your diet ends, your body is still
conserving energy. The amount of food that maintained your weight before
the diet may now increase it. Some researchers believe that the more
your weight fluctuates from yo-yo dieting, the more quickly your body
switches on its energy-saving metabolic slowdown with each new diet.
This process was demonstrated in an experiment with rats (Brownell et
al., 1986) who were fattened up considerably and then put on and off a
diet, creating a cycle of weight gain and loss. On the first diet, rats
lost their excess weight in 21 days and took 46 days to regain it. The
second time, eating precisely the same amount of food, they took 46 days
to lose the weight and only 24 days to regain it. It's as if our body
learns from previous diets how to defend itself more vigorously from
what it interprets as starvation.
Does this pattern
of losing and regaining pounds, with your base weight gradually creeping
upward apply to you or anyone you know? If the answer to this question
is yes, then the value of learning how to adjust your setpoint downward
should be obvious. To a large extent, but not totally, your setpoint is
determined by biological genetic factors. Some people, those who are
just naturally thin whatever they seem to eat, are blessed with
relatively low setpoints (and high resting metabolic rates) due to
hereditary factors. Others are biologically predisposed to be heavier
due to genetically programmed higher setpoints (and lower resting
metabolic rates). That is why it is possible for two people of the same
height, age, body build, activity level, and food intake to maintain
different weights.
Certain other
biological factors also affect setpoint. Your bone mass and frame
structure will certainly affect your weight. Age is a crucial factor.
Setpoints start to creep upward for women after age 30 and for men after
age 35. But the fact that your setpoint is partially biologically
determined does not mean that you should throw up your hands in despair
and give up if you are struggling with your weight. Other factors
affecting your setpoint are under your control. For the fact is that you can lower your setpoint! And once you lower your setpoint, the task of weight reduction is much easier to attain and maintain.
Lowering Your Setpoint
By now you are probably
wondering, “What can I do to lower my setpoint?” Actually, you can do
quite a few things that also have the added benefit of helping you cope
with stress as well. Drastic and dangerous fad diets are not the way to
go. Successful weight control involves changes in your lifestyle that
allow you to reduce and then maintain a healthy weight.
Increase Your Activity Level
A very important
determinant of your setpoint is your activity level. Regular exercise,
particularly aerobic exercise, can significantly lower your setpoint and
thus help you lose weight and keep it off. In general, lean individuals
have much higher activity levels than those who are overweight. If you
are not currently involved in a regular aerobic exercise program, we
strongly recommend you consider starting one. It will facilitate your
ability to lose weight even more than reducing your caloric intake. In
fact, sustained exercise can be a weapon against the body's normal
metabolic slowdown when reducing caloric intake.
Exercise promotes
weight loss because it builds muscle tissue, which has a higher
metabolic rate (that is, it burns calories faster) than fat tissue.
Exercise of all types, but particularly strength training, builds muscle
and improves the muscle-to-fat ratio in your body, thereby helping to
increase your metabolic rate. Thus, moderate amounts of weight lifting
should be included in any plan to lose weight because it builds muscle
mass, maintains muscle tone, and prevents muscle mass from being
replaced with fat as we age.
The amount of body fat
you possess depends on the size and number of your fat cells. An average
adult has approximately 30 billion fat cells. Fat cells can be
relatively empty, or full like an inflated balloon. In overweight
people, fat cells swell to two or three times their normal size and may
divide, producing additional fat cells. If your total number of fat
cells increases, due to overeating or genetic factors, it never
decreases. Thus we cannot reduce the number of fat cells we carry (short
of procedures such as liposuction); we can only affect the fullness of
each fat cell. Since fat tissue has a lower metabolic rate, it needs
less food to maintain itself than other types of tissue. Thus, once we
become fat, we require less food to maintain our weight than we did to
attain it.
Consider the perils of
inactivity. Lack of exercise can lead to weight gain. When people feel
fat, they are less likely to be physically active, setting up a vicious
cycle of inactivity. Oftentimes it is easier to just sit and watch TV.
But physical activity helps release the muscular tension produced by
stress. A correlational study of TV watching and obesity among 12- to
17-year-olds found that obesity was more common among those who watched
the most television. This association remained even when many other
factors were controlled, suggesting that the tendency to be a couch
potato in front of the boob tube actually contributes to obesity. It is
likely that the rise in obesity in American society is as much a
function of inactivity as reliance on junk food. As a culture we are
addicted to the automobile. Rarely do adults do any significant walking,
and the same is true of children who typically expect to be transported
wherever they need to go. This lack of physical exercise also
contributes to the fact that lifespans in America are among the shortest
in the industrialized countries.
One of the few predictors of successful long-term weight loss is exercise during and after changing eating habits. Check out Table 1 to see how much energy is expended by various activities.
Table 1. Calories Expended in One Hour, According to Activity and Body Weight
Activity
| Body Weight in Pounds
|
---|
100
| 125
| 150
| 175
| 200
|
---|
Sleeping
| 40
| 50
| 60
| 70
| 80
|
Sitting quietly
| 60
| 75
| 90
| 105
| 120
|
Standing quietly
| 70
| 88
| 105
| 123
| 140
|
Eating
| 80
| 100
| 120
| 140
| 160
|
Driving, housework
| 95
| 119
| 143
| 166
| 190
|
Desk work
| 100
| 125
| 150
| 175
| 200
|
Walking slowly
| 133
| 167
| 200
| 233
| 267
|
Walking rapidly
| 200
| 250
| 300
| 350
| 400
|
Swimming
| 320
| 400
| 480
| 560
| 640
|
Running
| 400
| 500
| 600
| 700
| 800
|
Decrease Your Intake of Refined Sugar
Another important
determinant of your setpoint is your consumption of refined sugars. Too
much sugar raises your setpoint. Lowering your intake of refined sugar
or eliminating it altogether will help to decrease your setpoint. The
average American adult gets 25 percent of his or her calories from sugar
in various forms, consuming an average of 160 pounds of sugar per year!
Sugar is a highly refined simple carbohydrate that provides absolutely
nothing nutritionally but calories.
The stress hormone cortisol
stimulates the hypothalamus, causing us to crave sugar for a temporary
mood lift. But the downside is that this process also facilitates weight
gain. Avoiding sugar is especially important if you are under stress
and are one of the three out of five people who are pre-diabetic or
pre-hypoglycemic. Some people have difficulty regulating their blood
sugar level and are thus prone to hypo- glycemia. When you eat foods
high in refined sugar, your blood sugar level shoots up, giving you a
little boost of energy along with a restless feeling. This sudden sugar
increase stimulates insulin production, which counteracts the sugar in
your blood. If too much insulin is produced, it leads to low blood
sugar. This results in hypoglycemic symptoms such as anxiety, dizziness,
irritability, depression, tremor, nausea, and hunger pangs. These
symptoms are partly due to the effect of the hormone epinephrine, which
is released when blood sugar levels fall dramatically. Epinephrine is
also one of the hormones involved in the fight-or-flight reaction; its
function here is to help raise blood sugar levels to give you the energy
to fight or flee. This is why the side effects of hypoglycemia feel
just like anxiety or panic. Low blood sugar also tends to prompt you to
have another treat. If you add environmental or emotional stress to this
vicious cycle, you can create an emotional roller-coaster that is hard
to get off, and sugar is one of the fuels that keeps it running.
Did you know that soft
drinks contain up to sixteen teaspoons of sugar per eight-ounce serving?
Also, if you take the time to read labels you will discover that sugar
is also a hidden ingredient in many food products, appearing under
different names such as dextrose, maltose, or corn syrup. In general, any ingredient ending with the suffix -ose or syrup is a sugar by-product. Try sweetening your foods or beverages with fructose,
derived from fruit sugar, instead of refined sugar. Fructose is
metabolized more slowly by your body, so it will provide sweetening
without triggering an increase in insulin production.
Decrease Your Consumption of Fats
Not all calories
are created equal. Calories consumed from fats are more likely to end up
on your belly or thighs than calories consumed from carbohydrates or
proteins. A gram of fat contains twice the number of calories provided
by a gram of protein or carbohydrate. If you can reduce your fat intake
to 20 percent of total calories consumed daily, your setpoint will begin
to lower on its own. Lowering your fat intake helps lower your
setpoint, thereby promoting weight loss more effectively than just
lowering your caloric intake. That is, a 1,200-calorie-a-day diet with
40 percent of calories derived from fat will lead to much slower weight
loss than a 1,200-calorie-a-day diet with a 20 percent fat ratio.
When shopping for food,
read the label on the can or package. Almost all canned or packaged
foods now have a chart on the back listing total calories per serving
and the grams of protein, carbohydrate, and fat per serving. To figure
out the fat content of a particular food or ingredient, just multiply
the number of fat grams by 9 to determine the number of fat calories per
serving. Then divide the total calories per serving by the fat calories
to get the ratio of fat to total calories.
For example, suppose
your favorite cereal has 100 calories per serving and contains just one
gram of fat. Multiply 1 gram times 9 and you get 9 fat calories per
serving. When you divide the 100 total calories by the 9 fat calories
you see that this food is only 9 percent fat and would definitely
qualify as a low-fat food. In contrast, a typical cookie contains
approximately 100 calories but usually has about 6 grams (or 54 fat
calories) of fat. Therefore, the cookie has over 50 percent fat content
and is therefore a high-fat food. Although each food has the same number
of calories, one promotes weight loss while the other does not.
There is now a
proliferation of low- and no-fat foods on the market from which to
choose. Make sure they do not compensate for being low-fat by having a
high sugar or sodium content (where you trade one dietary mistake for
another).
Watch Your Salt Intake
Your intake of salt
affects your weight as well as your ability to deal with stress. There
appears to be an interaction between salt and stress, since the hormones
that contribute to the fight-or-flight response also help regulate the
salt and water balance in your body. A diet high in salt can lead to a
tendency to retain water, which is particularly problematic for women
who experience PMS symptoms. Water retention can lead to symptoms such
as irritability and nervousness. In addition, a high-salt diet can
damage your arteries even when your blood pressure is within normal
range.
Drink Plenty of Water
Dehydration can lead to
irritability and fatigue. You may not necessarily feel thirsty even if
you are becoming dehydrated, so it is prudent to keep drinking fluids,
particularly if you are exercising or exposed to hot weather. Water
helps aid digestion and flushes toxins out of your system more quickly,
including toxins built up by stress. All weight-loss programs recommend
drinking four to eight 8-ounce glasses of water daily.