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Nutrition for Nursing Students, independent study

Weight Management 1

Brown, 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). Taking a broader view of the problem of an over-weight population, you as a health care provider ought to focus on the prevention of, and cure for obesity. 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 Nursing education, triggered by observed weight gain at patient visits to doctors. 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].

The Energy Balance Model

We begin with the concept that energy intake and energy expended are coupled together, and cannot be separated (except artificially). There are three alternate models for visualization of this coupling of intake and expenditure:
     1. From the chem lab, the double pan balance
      2. From business, the accounting ledger
    nbsp 3. From nursing, the patient I & O chart
You should try to understand all three, and then choose the one which makes the most sense to you as the preferred model [I recommend that you remember all three, in case you have a patient who can't visualize how the one you presented works].
    For all three 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 & ADLs plus calories burned by exercise. Most software (including DietAnalysis +, 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 patient remain compliant, so whatever you want them to do has to be easy enough to become a habit rather than quickly becoming an annoyance!

the double pan balance, explained

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 left pan; and energy expended, on the right pan. If the pointer points straight up, energy is balanced and the patient's weight should be stable [plus or minus daily fluctuations, explained below]. However, if the pointer leans to the left [intake side], the patient can expect to gain weight; or if it leans to the right [expenditure side], the patient should lose weight. This is the model shown in most Nutrition textbooks.

the accounting ledger, explained

The ledger consists of two columns: the debit column and the credit column, and usually space before the columns where explanations of entries can be written. By definition, a credit is an entry in the right column and a debit is an entry in the left column. By analogy with your bank account, where your paycheck is credited to your bank account, and processed checks 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 [daily, weekly, or monthly; quarterly is too long to be effective], we add up all of the credits and all of the debits. Subtract the smaller number from the larger number and record the answer (with the explanation “balance” under the larger number, or as a debit if it is zero. If it is a zero balance, the patient's weight should be stable. If it is a credit balance, the patient can expect to gain weight; or if it is a debit balance, the patient should lose weight. (You can also carry a “running balance” as a credit balance by adding each credit to the balance and subtracting each debit from the balance as they are entered [a positive running balance would be a credit balance, and a negative running balance would be a debit balance], but that would look a lot like work). I have not seen anybody else use this method, and you are not required to like it just because it is my idea.

The Energy Ledger
'account' debit credit
dietary carbs 4 kcal/g
dietary fat 9 kcal/g
protein 4 kcal/g
alcohol 7 kcal/g
basal metab.1 800 kcal/day
ADLs1 200 kcal/day
thermic effects
of food2
50 kcal/day
walk3 3 MPH 0.035 kcal/lb/min
bicycle3 15 MPH 0.039 kcal/lb/min

data from
(1) my estimate, based loosely on the USDA 1950 Food Guide Pyramid
(2) Segal, KR, and Gutin, B. 1983. "Thermic effects of food and exercise in lean and obese women." Metabolism 32(6) [1983 Jun]: 581-9.
abstract at: http://www.ncbi.nlm.nih.gov/entrez/ then search 'PubMed' for 'thermic effects of food'
(3) adapted from Sizer & Whitney. 2007. Nutrition, Concepts and Controversies, 11th ed. © Cengage (Thompson/Wadsworth)

the I & O chart, explained

The “I & O Chart” is used in hospital to track either fluid balance or hydration [the more familiar use] or food balance, or sometimes both.
  In the fluid balance I & O chart, the nurse [more often nurses aide] charts all fluid intake, and collects fluid output to be measured and charted. To maintain the patient's hydration, the two numbers should be equal. If output exceeds intake, the patient will become dehydrated. If intake exceeds output, the patient will become bloated.
  In the food balance I & O chart, the nurses aide estimates the amount of food eaten [plus that brought in by friends and relatives] and the quantity of the bowel movements and urinary output. This information can then be used to explain any change in weight.
  We could chart the patient's Calories the same way… using information from the nutrition facts label to get Calories in and estimates of Calories burned in exerciseto get Calories out. The patient can be assessed by reading the chart. If it intake matches output, the patient's weight should be stable. If it intake is greater than output, the patient can expect to gain weight; or if output is greater than intake, the patient should lose weight.

Energy Intake [credit side of ledger]

You could do this estimate the hard way, using the values in the credit column above to guess the patient's Calorie intake, but why would you want to? I had you buy a software CD that ‘knows’ how to guess what the patient's Calorie intake is from their reported diet, without your having to do algebra. And there are on-line calculators, such as MyPyramid, which do this also.

Energy Expended [debit side of ledger]

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”].

Dieting as weight management strategy

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 start 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 carbohydrates and fats). 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 impractical.

    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 paraphrase 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 referral for 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 referred for diagnoses of 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 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 serum glucose, 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 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. 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 serum glucose 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 serum 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 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/g, 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 effacacious for weight loss. The minor problem is that many “low fat” foods are high in carbohydrates, again compromising the effacacy 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 one persons diet for 7 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. As a Nurse you are more willing to chart patients than the patients are willing to chart themselves. 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].

Detection of weight change

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 above), or waist circumference, and men's pants size (which is still waist circumference; regular fit, and relaxed fit differ in hip circumference). Any change toward the target circumferences for the specific patient 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:

1 C.I. = confidence interval, 95 % of observations should lie within the C.I.
2 fat% data on 1 individual, measured electrically.
parameter n grand mean 95% C.I.1 C.I. as
% of mean
wt 16.1 148.2 0.54 0.36%
fat%2 19 18.6 0.77 4.14%

The presumption is that the variation in their weight is typical for the human population. If your patient's weight or fat% varies by an amount less than the C.I. quoted, you can conclude that their weight or fat% has not changed; and if it varies by more than the C.I., you could conclude that their weight or fat% may have changed, but not that it has changed.
The patient's weight would have to change by about 0.5 lbs/day to allow a conclusion that 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.


© 2004-2010 TwoOldGuys ™

revised: 05 Mar 2009