Brown (2008. Nutrition Now 5th ed, ©Thompson Learning, Inc), in the Key Concepts and Facts box at the beginning of Unit 10, points out that “Maintenance [emphasis added] of weight loss is the cure for obesity” (text, pg. 10-2). If you are a member of the over-weight population, you ought to focus on the prevention of (further) weight gain, and maintenance of weight loss, assuming you would like to live a long life, and have a good quality of life for your entire life. The maintenance of weight loss and the prevention of weight gain both depend on weight management. Perhaps if the general population could be taught to manage their weight, it would be a major step toward solving the problem [I am not so naive to believe that the problem will ever be completely solved]. It may be that the most effective way to begin teaching the general population how to manage their weight would be for Nutrition to be included in higher education for all Liberal Arts (Gen Ed) students, and for that Nutrition course to emphasize the role of good nutrition in wellness. On this assumption, I have expanded weight management to two lectures, rather than the one chapter/lecture in most Nutrition texts [and publisher provided sample lecture outlines].
We begin with the concept that energy intake and
energy expended are coupled together, and cannot be separated (except
artificially). There are two alternate models for visualization of this coupling of intake and
1. From the chem lab, the double pan balance
2. From business, the accounting ledger
You should read both, and then choose the one which makes the most sense to you as the preferred model.
For both models, “energy intake” is the number of calories consumed in the diet (including all snacks, and beverages other than actual [unsweetened] water). “Energy expended” is the number of calories burned by basal metabolism & Activities of Daily Living (ADLs) plus calories burned by exercise. Most software (including DietAnalysisPlus, and MyPyramid) offer the opportunity to enter exercise (and estimate basal metabolism & ADLs, based on age, height, & weight). It is extremely important to understand that, in science, all numeric values are estimates, so the numbers used in weight management do not require obsessive - compulsive attention to accuracy, and success in weight management does require that the person continues to pay attention to their “energy balance”, so it has to be easy enough to become a habit rather than quickly becoming an annoyance!
The double pan balance consists of a pedestal with a movable arm attached below the top. The arm has a pointer in the center where the arm attaches, and two pans, one hanging off each end of the arm. (This is the same scale seen in statues and paintings of the “scales of justice.”). Energy intake is placed on the right pan; and energy expended, on the left pan. If the pointer points straight up, energy is balanced and the person's weight should be stable [plus or minus daily fluctuations, explained below]. However, if the pointer leans to the intake side, the person can expect to gain weight; or if it leans to the expenditure side, the person should lose weight. This is the model explained in most Nutrition textbooks. Many students seem to have difficulty with the mental image of “weighing” energy.
The ledger consists of four or five columns: the first column is today's date, the second column is
where explanations of entries can be written. The next two columns are the debit column and the
credit column. By definition, a debit is an entry in the left column and a credit is an entry in the
right column. By analogy with your bank account, where your paycheck is credited to your bank
account, and processed checks (& debit card purchases) appear as debits to your account, we
shall enter energy intake as credits, and energy expended as debits. At the end of the accounting
period [weekly, or monthly (quarterly is too long to be effective)], we add up all of the credits
and all of the debits, and enter the totals in the appropriate columns, with the explanation
“totals.” Subtract the smaller number from the larger number and record the answer (with
the explanation “balance”)
under the larger number, or as a credit if it is zero. If it is a zero balance, your weight should be
stable. If it is a credit balance, you can expect to gain weight [just like maintaining a credit
balance in your bank account makes you wealthier; and you can transfer some of your wealth to a
savings account (“fat” is your weight saving account)];
or if it is a debit balance, you should lose weight [just like a debit balance in your bank account
makes you poorer].
You can also carry a “running balance” (in a fifth column, named “balance”) as a credit balance by adding each credit to the balance and subtracting each debit from the balance as they are entered, very much like the “check register” included with your personal checks. A positive running balance would be a credit balance, suggesting the possibility that weight gain may happen; and a negative running balance would be a debit balance, suggesting that weight loss may happen. In either case, a daily weight change may be offset by tomorrow's credits and debits.
I have not seen anybody else use this method, and you are not required to like it just because I am your professor and it is my idea. I, personally, like this approach, but then I have always been a little weird (according to my grand-daughters; my daughter just thinks I am slightly crazy).
|DATE||EXPLANATION of entry||USED||EATEN||BALANCE|
|dietary carbs account||4 kcal/g|
|dietary fat account||9 kcal/g|
|protein account||4 kcal/g|
|alcohol account||7 kcal/g|
|800 - 1,000 kcal/day|
|walk2 3 MPH||0.035 kcal/lb/min|
|bicycle2 15 MPH||0.039 kcal/lb/min|
|watch cable TV, using remote3||0.009 kcal/lb/min|
|TOTALS|| || |
|balance||lose wt||gain wt|
(1) my estimate, based loosely on the USDA 1950 Food Guide Pyramid
(2) adapted from Sizer & Whitney. 2007. Nutrition, Concepts and Controversies, 11th ed. © Cengage (Thompson/Wadsworth)
(3) this one, I made up.
You could do this estimate the hard way, using the values in the credit column above to guess your Calorie intake, but why would you want to? I had you buy a software CD that ‘knows’ how to guess what your Calorie intake is from your reported diet, without your having to do algebra [not to mention, the Nutrition Facts label discloses the Calories per ‘serving’]. And there are on-line calculators, such as MyPyramid or nutritiondata.com, which do this also.
Again there is the hard way, where you get to do algebra, or the easy way where you let the software
do the algebra [and software rarely complains about having to do algebra, even early on Monday
morning - algebra is what software does best-est, to paraphrase Tigger
or T I double-guh er].
The U.S. weight loss industry is a $33 billion ($33,000,000,000.00) industry, combining weight loss
products and services. Weight loss program advertisements often include claims such as
“easy”, “without exercise”, or “…and you can continue to eat the same
things.” The advertisements for many weight loss programs are highly seductive, because they
seem to promise weight loss without effort on the part of the person trying to lose weight.
Unfortunately, most people who join such programs either fail to lose weight, or fail to maintain
their reduced weight. There are only two possible explanations for this lack of success: either the
programs are flawed, or the people are flawed. I prefer to think that the programs are flawed, and
that people can maintain healthy weight “simply” by (a) learning how to manage their
weight, and (b) applying what they have learned to weight management. For most people, neither is
simple [I must admit, I did not find it simple to come up with this ‘simple’ concept of
weight management]. Ideally for a diet plan alone to cause stabilization of weight without
compromising wellness, the diet design would have to limit total Calorie intake (by reducing portion
sizes for carbs, fats, proteins, and alcohol) while paying close attention to meeting RDAs for all
essential nutrients (including carbs, fats, and proteins). Unless you happen to be Oprah Winfrey, you
probably can't afford to hire your own personal, full time trained dietician, so this ideal diet is
There are numerous books available promoting “diet plans” which recommend restricting one class of nutrients (often as low as zero intake) as the quick and easy way to lose weight. Some restrict dietary carbohydrates, others restrict dietary fats, and some restrict both carbs and fat. To evaluate these diet plans using critical thinking, you need to remember that the definition of starvation is “a condition in which intake of one or more nutrients is deficient.” Any diet plan which limits carbohydrates, fats, or both to less than the minimum daily requirement should be considered to be “induced starvation”. To quote from prescription drug commercials urging viewers to ask their doctor if the advertised medication is right for them, “These may be signs of a rare, but serious side effect which may be fatal,” except that in this case “rare” means approximately 100% of people on the diet. Ordinarily, we would consider a diagnosis of an eating disorder if a patient were to deliberately starve himself or herself, but when a medical doctor (Dr Atkins) published a popular book in which he recommended deliberate starvation relative to both carbohydrates and fats, his followers were not diagnosed with eating disorders, even after they started dying due to their inadequate (starvation) diet.
Low carb diets have two major problems. First is an evolutionary adaptation of Humans. Long before the Pleistocene Ice Age [even before the cartoon movie Ice Age], when the spring growing season started, the carbohydrate density of the food supply was low. The carbohydrate density of available foods increased until late summer, but then began to decline (fruit had ripened, and was becoming over-ripe). The early cavemen did not understand the concept of seasons, so they explained the change between seasons by superstition, but did not have good enough satellites to predict when the gods would be angered, so winter tended to come as a big surprise. Survival depended on having sufficient stored energy, so when the convenience store owners all went to Florida for the winter and there was no place to buy a Snickers, you could use stored energy. A trigger was needed to signal the body to start storing fat before winter arrived with its low food availablity. The best available trigger was the capability of the hypothalamus to detect blood sugar, and the ability of the cerebrum to remember trivia, such as “last time I ate one of these fruits, my hypothalamus said it provided more carbohydrates than this time.” This could be the Caveman's trigger for aggressive fat deposition. A low carb diet will provide currently living specimens of Humans with the decline in carbohydrate density in the food supply necessary to trigger fat deposition! This is directly opposite to the intended outcome of the low carb weight loss diet. It is only after prolonged carbohydrate starvation that fat mobilization begins to supply energy. Cavemen probably experienced starvation in several other nutrients during winter (especially Ice Age winters), which may trigger fat mobilization as an energy source sooner than in carbohydrate starvation alone. The other problem with carbohydrate starvation is that it triggers protein deamination and use of amino acids as an energy source. The deamination produces excess urea, causes uremia, which can lead to kidney failure and death. The amino acids deaminated come from breakdown of body proteins, not from dietary protein. These diets are probably doomed to failure because we have an instinctive craving for sweets triggered by a drop in blood sugar detected by the hypothalamus. The need for sweets is exactly why the taste buds for sweet are physically located on the tip of the tongue; we can estimate the potential energy intake of an object from the universe around us by touching the object with the tip of our tongue (don't forget, as couch potatoes we need 1,000 Calories a day, and very few cavemen used their remote control while watching cable TV).
Low fat diets have one potentially major problem, and one minor problem. It has been shown that one of the triggers of satiety (cessation of hunger) is the detection of an increase in blood fatty acids by the hypothalamus, so the low fat diet will fail to trigger satiety. As a result, the dieter will continue to experience hunger, leading to munching, usually on high carb density snack foods (chips, popcorn, etc) while watching TV [which also triggers appetite, the psychological drive associated with eating popcorn while watching movies, since TV is similar to a small screen movie experience]. Unless the potato chips are sufficiently oily, satiety will not be triggered by several hundred Calories worth of chips (at 150 Cal/oz & 10.0 g total fats, data from caloriecount, “a free service of About.com Health,” a website I have bookmarked). Several hundred Calories from high carb density snacks will not be helpful for weight loss. The minor problem is that many “low fat” foods are high in carbohydrates, again compromising the effectiveness of the low fat diet.
“Other” popular “easy” approachs to weight (mis)management are “behavior modification” programs and dietary supplements (magic pills) that purport to “increase [basal] metabolism.” Typical behavior modification programs involve the patient tracking their total food intake for months. You have tracked your or another person's diet for 3 days, and no doubt found it to be tedious and time consuming. Imagine doing this for several more months; at what point would you get tired of the game, and quit. These plans understandably have high drop-out rates. Once the patient drops out of the program, they resume their old habits and regain at least as much weight as they lost, frequently more.
There are no “magic pills” that increase metabolism. The ones I have investigated contain phytochemicals which are the coenzymes of the electron transport system (ETS), as their active ingredients. Your coenzymes of the ETS are in your mitachondria, and every mitachondrion you own already is saturated with these coenzymes. Not only do you have all the coenzymes of the ETS you can use, mitachondrial DNA codes for these enzymes, so you make more whenever you need them, which is why they aren't listed as vitamins! The only known way to increase basal metabolism is to grow more mitachondria [which is covered in the next lecture, Weight Management 2].
With any luck, you still remember that our goal here was to develop tools that could allow real
people to do weight management to maximize their wellness. Surprisingly, the first step in monitoring
the success of a weight management program is to hide the bathroom scales. There is a single, simple
measurement which has been shown not only to be very effective in monitoring weight management, but
also has relatively high correlation (statistical) to the risk factors for adipose-related health
issues. That measurement is women's dress size (although dresses have been re-sized to larger
circumferences in the three key circumferences listed in the lecture on ‘Body Weight’), or
waist circumference, and men's
pants size (which is still waist circumference; regular fit, and relaxed fit differ in hip [and thigh]
circumference). Any change toward the target circumferences for anyone should be gradual; and the
change should slow down over time as they approach the target.
When I learned that one behavior-modification weight loss program had “celebrations” for those clients who had lost a pound or two over a week, I became curious about the amount of change in weight which could be considered significant. I was unable to find any data on normal weight variation in Humans, so I assigned College students taking my Nutrition course at Ancilla College, Donaldson, Indiana, the task of weighing an actual person daily (same time each day, preferably first thing in the morning when the patient could be expected to have had little water intake or output for several hours). I analyzed their weight data on 10 individuals for average of 16 days. The population of weighed individuals exhibited the following:
|parameter||n||grand mean||95% C.I.1||C.I. as
% of mean
The presumption is that the variation in their weight is typical for the human population.
If your weight or fat% varies by an amount less than the C.I. quoted, you can conclude
that your weight or fat% has not changed; and if it varies by more than the C.I., you
could conclude that your weight or fat% may have changed (but not that it has changed).
Your weight would have to change by about 0.5 lbs/day (for a whole week) to allow a conclusion that your weight has changed; and fat% would have to change by about 0.8%/day to allow a conclusion that fat% has changed. Under the best of all possible scenarios, the patient's weight could initially change by a relatively large amount (say 2 to 3 C.I.). Long term, the patient's weight should change by less each time they are weighed, as they approach the target weight.
The electrical measurement of fat% is sensitive to hydration, accounting for the relatively high confidence interval (4% of mean). It seems reasonable to assume that hydration status also accounts for the weight variance. The human body is about 60% water, so the average water weight of the above population should be 60% of 148.2 lbs = 88.9 lbs H2O. Since the loss of 5 - 6 lbs of sweat during fitness exercise is reasonable, the loss of 0.54 lbs [1/10th of reasonable sweat loss in 30 min] of water in a day is not unreasonable.
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revised: 20 Aug 2010