Why Some People Gain More Than Others

[Guest guest]

Why Some People Gain More Than Others

Learn why some people can eat what they like and never gain weight.

The Difference

Everyone knows some people who can eat ice cream, cake, and whatever

else they want and still not gain weight. At the other extreme are

people who seem to gain weight no matter how little they eat. Why?

What allows one person to remain thin without effort but demands

that another struggle to avoid gaining weight or regaining the

pounds he or she has lost?

The simple answer is that your weight depends on the number of

calories you consume, how many of those calories you store, and how

many you burn up. The balance of calories stored and burned depends

on your genetic makeup, your level of physical activity, and your

resting energy expenditure (the number of calories your body burns

while at rest). If you consistently burn all of the calories that

you consume in the course of a day, you will maintain your weight.

If you consume more energy (calories) than you expend, you will gain

weight.

What Determines Your Metabolic Rate

Total metabolism is the rate at which you use energy (measured in

calories) when you're exercising or doing anything else (including

sleeping). Resting energy expenditure is the rate at which you burn

calories when you are not being physically active. Resting energy

expenditure varies from person to person and is affected by your

age, gender, genetic makeup, psychological state, and level of

physical activity. For example, pregnancy and illness both tend to

increase resting energy usage. Both total metabolism and resting

energy expenditure influence your weight by affecting how many

calories you burn in the course of a day.

Excess calories are stored throughout your body as fat. Your body

stores this fat within specialized fat cells (adipose tissue) --

either by enlarging fat cells, which are always present in the body,

or by creating more of them. If you decrease your food intake and

consume fewer calories than you burn up, or if you exercise more and

burn up more calories, your body will reduce some of your fat

stores. When this happens, fat cells shrink, along with your

waistline.

Storing Too Many Calories

The more complex issue is why some people store more calories than

they burn. Is it a matter of willpower? Do overweight people simply

eat too much and exercise too little? Until recently, even weight-

loss experts could not agree on the answers.

Some experts argued that the explanation was genetic: that some

people are genetically destined to be thin, others to be overweight.

They suggested that overweight people have thrifty metabolisms,

which conserve energy and predispose them toward fat storage. Other

experts pointed out that many features of modern life promote weight

gain. For example, we don't get enough physical activity because we

drive to work and spend much of our day sitting at computer

terminals. We have trouble finding the time to go to the gym, play a

sport, or exercise in other ways because we work long hours. With

the majority of mothers now in the work force, working parents have

the extra pressure of coming home and caring for children after a

long workday. Perhaps we overeat because practically everywhere we

go -- shopping centers, sports stadiums, movie theaters, and so on --

fast-food restaurants and snack bars tempt us with oversized

portions of high-calorie foods and drinks. In short, these

environmental factors lead us to eat too much and get too little

physical activity, with the result that many people are overweight

or obese.

Still other experts stressed that people's eating habits and weight

are related to how they handle stress and cope with difficult

situations. Many people who are overweight also suffer from

depression and other emotional conditions that may exacerbate their

tendency to overeat.

Genetics, Environment, Psychology

Now, weight-loss researchers recognize that all three of these

factors -- genetics, environment, and psychological issues -- can

contribute to weight disorders. Most overweight people are

genetically predisposed to being overweight. But many of these

people wouldn't be overweight in an environment that promoted

healthier food choices and encouraged physical activity. Because of

these genetic and environmental influences, most people who become

overweight have trouble losing weight and keeping it off. This

difficulty understandably leads to frustration that can cause

depression, anxiety, binge eating disorder, and even bulimia. These

psychological complications may interfere with healthy eating and

exercise habits, leading to further weight gain and a vicious cycle

that only magnifies the problem. Many people have the experience of

losing weight only to gain back even more and then repeat this cycle

many times over the years.

These three factors -- genetics, environment, and psychology -- do

not affect all overweight people to the same degree. For some

people, the cause is so strongly genetic that they would be

overweight regardless of other factors. For others, the genetic

predisposition to be overweight is less powerful, and environmental

factors have the dominant role. The foods these people eat; how

much, how often, and when they eat; and the lack of time for

physical activity conspire to make them gain weight. For some

people, emotions play a dominant role, either because they tend to

overeat in response to stressful situations or because they use food

to diminish the effects of psychological trauma.

To optimize your chances for maintaining a healthy weight, think

about which of these factors contributes to your weight problem.

Understanding the role of these factors can help you determine the

best approach to achieving and maintaining a healthy weight.

From the Harvard Health Publications Special Health Report Weigh

Less, Live Longer.