Positive Energy Balance means Energy in > Energy out (Weight Gain)

Negative Energy Balance means Energy in < Energy out (Weight Loss)

Equilibrium is considered +/- 300 Calories (Weight Maintenance)

If you eat 3500 more Calories in a week than your body needs, you COULD gain one pound, because a pound of fat is equal to 3,500 Calories.  Notice I say COULD.  Your text book discusses a study of identical twins who were given an extra 1,000 Kcals a day for 100 days.  Some set of twins gained less than 10 pounds, while others gained up to 30 pounds.  People gain and lose weight differently, we don't necessarily follow formulas.

If a person is sedentary or moderately active, BMR is the body's largest energy expenditure.  A sedentary person might need about 1800 calories in a day, with about 1200 of them being for the BMR.

An accurate way to measure energy expenditure is to measure oxygen use, since oxygen is needed to complete the Krebs cycle.

 

B.    Voluntary activity is the other important way the body expends energy.

Examples would be irregular activities like dashing to class or regular activities like lifting very heavy weights or swimming.

C.  Thermic Effect of Food

This is the stepped up metabolism that happens when eating a meal.  About 5 to 10% of calories in a food are lost because that energy is used to digest and absorb the food.  However, its effects are negligible and is not considered when calculating Calorie needs.

Using just the BMI, at the time of this photo, Michael Jordan would have been considered obese.

1. DEXA scan.  Although I don't know who this is, it is what I had done to check my bone status.  Although it is the most accurate way to measure body composition, it is also very expensive and is usually just done in medical settings.
   
   
   
2. Underwater weighing.  Next to a DEXA Scan, underwater weighing is the most accurate way to measure body composition. This is based on the principle that fat "floats".  
   
   A person is first weighed.  They then exhale as much air as possible and are immersed under water for 10 to 15 seconds for an underwater weight measurement to be taken.  The difference is their lean (muscle and bone) body mass.
   
   This procedure is repeated 7 to 10 times. Total test procedures may require 45 minutes to one hour.
   
   
   
   
   
   
   
   
3. Fatfold test.  Skinfold calipers are another way to measure body composition, but they're not considered accurate because it's difficult for 2 different people to pinch and squeeze the same way.  A suitable use is for one person to do the measuring, then the SAME person do it after 3 months or so to see if there's been a change.
   
   
   
   
   
   
   
   
   
   
   Notice the Gray's Anatomy textbook.
   
4. Bioelectrical impedance.  Only lean tissue and water conduct electricity.  The fat does not.
   
   

    

   

   Above is hand-held device for measuring body composition using bioelectrical impedence.
   
   

   

   
   

   
   This is a scale you can stand on and measure body composition using bioelectrical impedence.  Students have told me that there are much cheaper ones available, but I'm not sure of their accuracy.
   
   
5. "Bod Pod".  This is a fairly new way of measuring body composition and the one pictured below is at the UO Treatment Center beside Autzen Stadium.
   
   While a person sits inside the enclosure, a rapidly vibrating diaphragm in the wall of the test chamber produces small changes in air pressure between it and an adjoining reference chamber.
   
   The changes in air pressure can be used to determine the amount of air the person displaces in the test chamber. In turn, that measurement leads to an estimation of the person’s body volume, corrected for the volume of air in the lungs at the time of the measurement.
   
   Then, taking the person’s body mass (obtained by a scale) and dividing it by the person’s body volume, the body density is determined. With that, a person’s percent body fat can be calculated.
   
   

1.    There could be genetic variations in perceptions of hunger and  appetite.

As mentioned before, hunger is the physical need to eat.  Genes in fat cells direct the making of ghrelin, a peptide hormone produced by stomach and small intestinal cells.  It is thought to increase feelings of hunger in order to stimulate eating.

Appetite is the psychological desire to eat creating satiety (feeling full). Genes in fat cells direct the making of leptin, also a peptide hormone, but one that is produced by adipose (fat) cells. It plays a role in body weight regulation by acting on the hypothalamus to suppress appetite and burn fat stored in adipose tissue.

Perhaps the brain cells of obese people ignore these hormones, just as some diabetics' cells (Type 2 diabetics) ignore insulin.

Eve Van Cauter, an endocrinologist at the University of Chicago who is shown above, calls ghrelin and leptin the “yin and yang" of eating regulation.

In experiments by Van Cauter and others, sleep-deprived adults produced more ghrelin, a hormone that promotes hunger, and less leptin, a hormone that signals fullness.

2.    Genes could also produce enzyme variations. 

The more your genes direct the making of lipoprotein lipase enzyme (LPL), the more easily fat cells store fat.   

As page 326 in the text says, LPL is "an enzyme mounted on the surface of fat cells that splits triglycerides in the blood into fatty acids and glycerol to be absorbed into the cells for reassembly and storage".

3.    Genes regulate thermogenesis, sometimes called the thermic effect of food (TEF).   Some people's genes may direct the expenditure of a lot of energy in thermogenesis, producing abundant heat without performing any useful work.

There could be less of a TEF happening in obese people.  

If you were a hunter-gatherer who lived in a feast & famine situation, would you like to have a high TEF?

1. Although some people work out when watching TV, many of us are not moving much, so it takes away from the hours of moving in the day.
   
   
   
   
   
   And TV can have what I call the "zombie effect".  Two of the children in the photo above have parents who were LCC nutrition faculty at the time and watching TV turned them into "zombies". 
     
   Research has shown that while watching TV, BMR falls even lower than just sitting around when you're not watching TV.
   
   
2. People often mindlessly snack when they're watching TV.  Since they're not really paying attention to what they eat, they may eat more than they need to be satisfied.
   
   
3. Many TV ads are for highly processed and high calorie foods and the ads make you want the food.
   
   
4. Many of the actors and actresses on TV have unrealistic body shapes which might encourage eating disorders.       
   

These are all of the sight, sound and smell cues in our environment that encourage us to overeat.

Foods high in sugar are especially tempting and take the least energy to digest.  Foods high in fat are also very tempting.  They take a lot of time to digest, but they may not satisfy us because they don't take up much room in our stomach.

I saw the below image at a conference I went to on obesity, where the speaker was  comparing our current situation (a body that is set up to deal with scarcity, not abundance, in an environment where we have every reason to over eat, and not move) to a polar bear in the Sahara dessert.  A polar bear is designed to withstand frigid temperatures, not heat.  We physiologically are wired for hunter and gather lifestyles where we have to work really hard for precious Calories in return.  When we are put into our current "toxic" food environment our bodies go haywire, and as a result are developing chronic diseases like heart disease and diabetes at alarming rates.  

A big external cue that encourages us to eat is marketing.  Watch the following clip on food marketing.

D.    Some people overeat because of

We get all sorts of cues in our culture that dieting is a good thing.  But weight loss diets seldom are successful in achieving long-term weight loss.  Instead, what can happen after successful weight loss is that the person begins overeating, gaining more weight than what they weighed before the diet.

1. Genetics.  Eating disorders run in families and it's easy to assume the family environment led to the problem.  Recent studies of twins, presumably raised in the same environment, are finding a clear genetic link. “In a large study comparing the number of identical twins who had anorexia with the significantly smaller number of fraternal twins who had it, scientists concluded that more than 50 percent of the risk for developing the disorder could be attributed to an individual's genetic makeup. A few small studies have even isolated a specific area on the human genome where some of the mutations that may influence anorexia exist, and now a five-year, $10 million NIMH study is underway to further pinpoint the locations of those genes.” (Tyre, Newsweek)
   
   Twin studies have also looked at bulimia. “Women with bulimic or anorexic female relatives are four to five times more likely to develop the disorder, and twin studies reveal that the genetic risk factor may be as high as 58 percent.” (Psychology Today)
   
   Perhaps genes help create a brain chemistry that can lead people to use starvation (or over-eating) as a way to control anxiety.  Serotonin is a chemical messenger in the brain made from the essential amino acid tryptophan and it affects emotions, behavior, and thought.  Normal levels of serotonin are believed to be associated with feelings of well-being.  Both low and high levels of serotonin may be associated with certain mental health disorders.  Both starvation and over-eating could be attempts to return brain serotonin levels to normal.  It has been suggested that the brain of a person with anorexia may have increased serotonin activity.
   
   
2. Control Issues. Most of us have a desire to control what's happening in our lives, and in varying ways.  When we feel ourselves losing that control, some can temporarily “go with the flow” until they can find satisfying ways to re-gain it.  Others may lash out with violent behavior or seek escape with drugs or alcohol.  Still others may decide to use not eating or over-eating to feel a measure of control.  All of these ways of seeking control can have a genetic basis, as evidenced by the incidence of alcoholism in families.
   
   
3. Culture.  Our culture places tremendous value on narrow aspects of image such as thinness. Rather than pursuing their unique interests and goals, many who don't fit this image become preoccupied and depressed if they don't naturally fit this image.  When they lose weight, some may tell them how good they look.  This gives the message that they didn't look good before and they can feel they probably don't look good yet.  So they keep dieting and for some reason we don't understand, the eyes of a person with anorexia see a fat person in the mirror, even when they're dangerously underweight.
   
   
4. Stressful/Traumatic Events.  Examples I've seen include a teenager whose boyfriend teased her because of her “thunder thighs” and broke up with her, parents who insisted on dieting because their child was being taunted, a parent's serious illness, the stress of college applications, a messy divorce at age 40 and a high-school exchange living situation in Mexico where the family was domineering and demanding. It's impossible to avoid stressful and traumatic events, but empathy regarding the impact of life experiences can be very helpful.
   

1. Total health  enhancement and well-being, rather than weight loss or achieving a specific "ideal weight."
   
2. Self-acceptance and respect for the diversity of healthy,  beautiful bodies, rather than the pursuit of an idealized weight at any cost.
   
3. The pleasure of eating well, based on internal cues of hunger and satiety, rather than on external food plans or diets.
   
4. The joy of movement, encouraging all physical activities rather than prescribing a specific routine of regimented exercise.
   
   Comparison of Traditional Weight Loss Paradigm and Health at Every Size (HAES)

Traditional	HAES
Everyone needs to be thin for good health	Thin is not intrinsically healthy and beautiful nor is fat unhealthy and unappealing
People are overweight b/c they have no willpower, they eat too much, and move too little	People naturally have different body shapes and sizes and different preferences for physical activity
Everyone can be thin, happy, and healthy by dieting	Dieting usually leads to weight gain, decreased self esteem, and increased risk for eating problems. Health and happiness are not dependent on weight.

How does your approach or thoughts about weight loss compare to the above?  Do you take more of a traditional approach or HAES approach?  Which approach do you think would be more positive in a health care setting?