Passing it off as conflicting metabolism patterns, they learned to live with it (or, should I say, Sue learned to live with it).
Basal Metabolism Difference
They're correct in saying that it could result from a basal metabolism difference. Kathy was an active kid (although she isn't today) and appears more muscular than her sister. Sue was always quieter and is still basically sedentary, and she looks like she carries more body fat than Kathy. This would lead us to assume that due to her greater ratio of muscle to fat, Kathy naturally burns more calories each day and therefore can eat more. It makes sense, right?
Well, this is only part of it. The question is: what causes their metabolism rates to be so entirely different?
Last year, Sue went on a diet. It wasn't a very healthy diet, though. She essentially restricted her caloric intake to about 800 per day for a full month. She lost ten pounds that month, a feat that she was very proud of, but soon, she stopped losing weight. She had hit a plateau, and 800 calories per day had become what she needed to maintain her current weight. She grumbled with discouragement when the scale stopped showing a reduction, and she went off the diet, feeling like a fat-fated failure.
What do you think happened to Sue's body then? You guessed it - she gained the ten back, with interest. She had been losing weight like crazy all month long. Why would this happen?
The Setpoint Theory
One possibility lies in a weight control theory called the Setpoint Theory. This was developed when several researchers indicated that each person's body has an established weight (a "setpoint") that it strongly tries to maintain. According to the theory, the body determines how much fat it wants to hold, and as the caloric intake climbs and falls, the body adjusts its basal metabolic rate to maintain that fat-to-muscle ratio.
This can work either way. At Rockefeller University in New York, researchers monitored many Sues and Kathies who had recently lost 10% of their body weight. It was found that, as their bodies worked to regain the weight, they began to burn calories more slowly (15% fewer calories than expected for their weight). When the Sues and Kathies began the study by gaining 10% of their body weight, they began burning 10 to 15% more calories than what would be expected, indicating that their bodies were attempting to lose the extra pounds and get back to their pre-set weight.
At the risk of spoiling any mystical charm implied here, the setpoint is probably just a defense mechanism that we inherited from our ancestors. Back in less luxurious generations, people lived at the mercy of the weather and the forces of nature.
There were times when food was plenty and there were times when they might go for days between meals. Their bodies, accustomed to this fluctuation, reacted to fasting periods by holding onto as much body fat as possible to prevent or postpone starvation. Today, most of us don't have to live with such hardships, but our bodies are still programmed for them, whether we like it or not.
The Fat Cell Theory
Another good candidate for explaining this is the Fat Cell Theory, which has been tossed around for about thirty years now. It attests that fat cells are usually formed either in early childhood or at puberty. A child who consumes a large number of calories from fat can actually grow new fat cells (hyperplastic obesity), whereas an adult will keep the same number of fat cells and they just expand (hypertrophic obesity).
Having a larger number of fat cells make it much more challenging to maintain a healthy weight in later years. Lean eating and exercise shrink these cells, but since there are so many, it's impossible to lose much of the excess body fat. Extremely obese adults can have as many as five times the number of fat cells that leaner adults have, making exercise seem pointless and ineffective.
Although hyperplastic obesity is thought to be quite rare, it's definitely something we should know about, especially those of us who are raising children. The hypertrophic type is much more common. Most of us who have packed on a few extra pounds here and there have simply expanded our fat cells, and shrinking them takes a little diligence and discipline.
How To Lose It
At any rate, whatever we believe to be the cause of weight gain, the solution is crystal clear. A combination of aerobic exercise and a diet high in complex carbohydrates is the best, longest-lasting weight loss strategy there is.
The Carb Rumor
Complex carbohydrates, also known as polysaccharides, are found mainly in plants. Corn, nuts, seeds, legumes and roots are all sources of complex carbohydrates, but for nutritive purposes, your best bet is in grains and other fiber-rich food sources. Whole-grain cereals, breads, fruits and legumes are wonderful choices with lots of nutritional virtues. A healthy diet is comprised of more of these than anything else.
Remember that one gram of carbohydrate has only four calories, where a gram of fat has nine, so you can eat twice as much of the former, causing that feeling of fullness to occur after fewer calories are taken in.
When you hear someone say that bread makes you fat, don't believe it. This is only true of certain groups of people - not the general population, and this notion has had a weed-like effect on health enthusiasts around the world.
Carbohydrates may cause weight gain in people who are either already morbidly obese or extremely sedentary. Very heavy people have a hard time using insulin efficiently, and carbohydrates tend to release increasing amounts of it. Since insulin is needed for the body to convert glucose to energy, if this function is impaired due to obesity, Diabetes or whatever else, the glucose is simply converted to fat, resulting in weight gain.
Most bodies immediately convert carbohydrates to energy, however. If this energy is used on physical activity, the body burns fat in the process. If energy is taken in, but the body doesn't move (for example, if someone sits on the couch, watching TV, eating cereal and fruit and all that good stuff), the energy has nowhere to go, so the body converts it to fat.
Carbohydrates don't make this person fat - it's just that inactive people don't use carbohydrates as energy nearly as efficiently as active people do.
People who exercise need lots and lots of carbohydrates for energy. You cannot, in any healthy manner, improve your ability to burn fat without exercising, so ignore all the hype about carbs being fattening. Hopefully, that whole craze will be over in a few years, once it finally becomes officially established that it's unhealthy.
When you begin increasing your aerobic activity and fiber intake, it's vital that you also drink plenty of water (at least two liters per day). Your body will need it, and it will help you burn fat much more quickly by keeping your liver and kidneys in check. Your liver can't metabolize fat very efficiently at all without sufficient water.
Aerobic activities include walking, jogging, bicycling, dancing and swimming. Anything that you do that involves the large muscle groups, which you can sustain for thirty minutes or longer, is considered aerobic. It should be done a minimum of five days a week for at least thirty minutes each session.
It should be intense enough to get your heart rate up, but not so intense that you become short of breath. In other words, you should be able to have a reasonable conversation during the activity, but you shouldn't be able to recite the Gettysburg Address without becoming winded.
Above all, it should be an activity you enjoy. If you hate the treadmill, don't chain yourself to it. Find something that you love and make it a can't-miss part of your daily routine.
Alas, some of us have to work harder than others to maintain slenderness. Consider it a character-builder. Remember, also, that by the discipline and sweat required to lower your setpoint, you are also strengthening your heart, lowering your blood pressure and LDL cholesterol level and probably prolonging your life.
Kathy might stay thinner than Sue with no effort whatsoever, but who knows how healthy she really is? Sue might actually be the lucky one, if you think about it. She has a good, strong driving force to do good things for her body, and that will surely pay off in the years to come.