#######################################################################################
##############                    To Do                                  ##############
#######################################################################################

height, weight and fat % will be the independent variables, but fat will be constrained by (the explanation below)
    >>NP - FFM range for men is 18.5/1.15*h^2 to 30/1.15*h^2, for women 18.5/1.23*h^2 to 30/1.23*h^2.
        >>This comes from assuming average % fat for people in this range (15% for men, 23% for women).

The lower limits above assume a very low FFM with average % fat - you can go below this limit by pushing down % body fat.
    Note that the lower limit is around a BMI of 16. At this point, you will be very low % fat and can begin removing FFM to drop weight,
    but you are now in the danger zone.

The graphs start at 22 years even if I put in that I'm starting at 38.  Can you have them start where the sim age starts?

I was wondering if you could add a feature to the slider that makes it so clicking ahead of
    the arrow in the slider increments the slider in small steps?  It’s hard to set things with them (as you predicted). 
    I can use the text box or I was wondering if it’s easy since you wrote them, to add this feature?

I am not sure that I entirely agree with your calorie expenditures for physical activity.
    They seem a bit high and in many cases are absolute values. The total caloric cost for weight
    bearing activities should be based upon a per body weight value. What was your source for this information?

Wendy wants exercise to be in 1/2 hour units in stead of 1 hour. This should be as simple as dividing all the calories by 2. There should be some indicator in the sim that these exercise calories are for 1/2 hour.

Add and change all images for food and exercise.

____________________________________________________________________________________________
FOOD LIST

NP: I added some more food items to the foods list. Some things to note:

-I added a hot dog with bun - I think you should remove the just plain hot dog (almost nobody eats just a plain hot dog, and the graphic shows a hot dog with bun...and a graphic for just a plain hot dog might be, well, distracting...)

-The "tall hot choclolate" should be changed to "regular hot chocolate" or maybe "large..." Tall sounds too much like Starbucks. We want to avoid reference to them.

-There should be a different graphic for diet cola and regular cola, if possible. Even if it is just a different color - just to show they are different. Same would be nice for milk, but I'm not sure right now how to do that.



____________________________________________________________________________________________
HEART STRENGTH / STRAIN

- Heart strength: this is a bar chart based a running average of exercise amount over the last X days (let's try X=30 days to start).
NP will determine the range for heart strength based on exercise. For now, lets make it 250-1000 cal/day as the healthy range.
    >>SR: Should this account for activity (lifestyle), or just exercise on top of that?

- Heart strain: this is a bar chart based on a running average of % fat over the last Y days (again, try Y=30 to start).
Similarly, there should be possibility of more permanent constants that can accumulate (to be determined).

The green area of each bar will mean good, red bad. The bright green area should be extended to include all acceptable values.
 So for heart strain, base this on 6-25% for men, 16-31% for women. (See below in CALCULATING BODY FAT... for where these values come from.)

There should also be the possibility of adding/subtracting constants based on other accumulated factors (e.g., if you go into starvation mode,
 you should lose some constant amount of heart strength that you can never gain back).
    >>SR: let's wait and see how the rest of the model looks before implementing this case
____________________________________________________________________________________________
MUSCLE AND FAT MASS LOSS


NP - weight lost should be both muscle and fat. There should be some ratio of FFM to Fat mass that is probably constant
whenever someone loses weight.

Article: Weight Loss-Induced Skeletal Muscle Loss: Accurate Estimation by Bioimpedance Analysis (BIA)

http://www.halls.md/fat/muscle.htm

Authors: Nuñez C, Kovera A, Wang ZM, Heymsfield SB.
Presented at : 8th International Congress on Obesity, Paris, August 29-September 3. 1998.
Abstract

Objective: Loss of skeletal muscle (SM) is a characteristic body composition change associated with weight reduction treatment.
    Prevention of dieting-SM atrophy with appropriate food composition or exercise is an important research goal.
Design: This study evaluated the accuracy of BIA (50kHz) in monitoring leg SM changes in a group of 71
        obese women (X±SD, age, 40.0±7.3 yrs; BMI, 31.1±2.8kg/m2)
        undergoing 16-week weight loss treatment on conventional low calorie diet.
Results: ***Subjects lost mean of 4.9 kg body mass, 4.3 kg as fat and 0.6 kg as fat-free mass.*** 

>>> So based on this, muscle loss is maybe 12% of total weight loss when dieting. Seems reasonable.

>>> Model: when weight is lost due to lower calorie intake than expenditure, 12% of calories come from lean body mass, 88 % come from fat mass. 		    
	Remove 4 g for every LBM calorie lost, 9 g for every fat calorie lost.

	So for example, if you take in 100 calories less than you burn, 12*4=48 g of LBM and 88*9=792 g of fat are lost.

>>>Model for weight loss:

	LBM_lost (g) = 0.12 * 4 * Cal_burned
	Fat_lost (g) = 0.88 * 9 * Cal_burned

>>>Starvation mode:
	When starving (<2%/4% for men/women) make the ratio switch, with buffering as follows:
		%fat 2-4% (men), 4-6% (women): 	LBM loss 50%, Fat loss 50%
		%fat < 2% (men), < 4% (women): 	LBM loss 95%, Fat loss 5%. (this might become 100% LBM...not yet sure).

Franny said on 6/13/2008:
    I have been playing with the Simulation this morning and had a question for you.
    If in this simulation it appears that the change in percent body fat is at a high rate when making even the smallest change.
    I had a diet that I let run for a few years that was 50 cal above my energy expenditure and i watched my %
    fat go up by about 15% in a few years and then when I added a walking exercise (one of the lowest calorie expenditures)
    in a matter of 1 year I went from 30% body fat to about 10% body fat. I was wondering if there
    was a way to slow down the change in % body fat. i am not sure if it is equation based and has a time function built in,
    but that portion is not very realistic, so i thought i'd point it out.

____________________________________________________________________________________________
MUSCLE GAINED FROM EXERCISING

>>SR: How does this relate to the MUSCLE AND FAT MASS LOSS section?
>>SR: Does this account for lifestyle/activity, or just exercise?

   - there should be some muscle gained from exercising, to a point. This should be limited (you can only get so muscular).
   I had trouble finding anything on this, so I made up a model that seemed reasonable.

>>>Model: For every calorie exercised, all of the calories are burned.
In addition, your body tries to make 10% of that number of calories into muscle, at a rate of 1/4 g of muscle per calorie.
So for example, if you do 1000 calories of exercise, all of those calories are burned.
In addition, 100 calories of what you eat are are turned into muscle (or 25 g).
These calories are in addition to those burned to do the exercise itself.
At this rate, one would build about 1 lb of muscle in 18 days, which seems reasonable.
There is also feedback so that the more muscle you have, the less you can build,
and at some point you cannot get any more muscular.

>>>Model for muscle building from exercise:

	Muscle_mass_gained = 0.1 * Cal_exercise * (LBM_0 - LBM)
	
	...where LBM is lean body mass, LBM_0 is 0.96 * sqrt(height / 30),
	or the lean body mass of a person with 4% body fat and a BMI of 30.

>>>These two features above will effectively make BMR vary according to
your caloric intake (if you undereat, your BMR should drop some to compensate, vice versa for eating more and exercising).
   
>>> all other weight gained is added fat mass.

____________________________________________________________________________________________
STARVATION AND HEART ATTACK

Starvation mode should be Gender specific: what are the threshould %fat values for male & female?

NP - let's say 2% for men, 4% for women.

>>>Model for starvation:
	If you drop below 2%/4% (men/women) fat, you can live for 2 months and then death occurs. If you go above this level, the clock resets.
	
	See MUSCLE AND FAT MASS LOSS section above for LBM and Fat loss when in starvation mode. (Basically you burn more muscle since you have so little fat.)

>>>Model for heart attack:
	If you go above 25%/32% (men/women) fat, you begin to have a probability of heart attack each day, p_attack. Below these %fat thresholds, p_attack = 0.

	p_attack = p_0 * (%fat - %fat_0)

	...where p_0 is a constant we adjust to make heart attack fairly likely (within a couple of years) for $fat > 50, %fat_0 = 25%/32% for men/women.
	

#######################################################################################
##############                    To Discuss                             ##############
#######################################################################################

Add Eating / Exercise labels to each side of the screen?  We removed the Edit Diet/Exercise buttons, which were partially serving as labels.

Shouldn't be able to set more than 24 hours/day
    >>SR: Is this a real problem?  If each icon is one hour, then the screen will be too overloaded at 24 to make any sense.  I'm not sure this problem is worth addressing.

Performance: consider profiling or changing clock rate
    >>How severe is this problem?

Time readouts should be Years:Months, not years in decimal
    >>Wait for interviews

Consider a 2-layer human graphic to show a "layer" of fat over a muscular interior

How should health indicators be wired up to heart health?

What are parameters for health indicators?

Add popup-question mark button for BMI readout near scale
    >>Not a great place for this near the scale, should it go below the scale?  Just appear when help is pressed?
    >>Ingrid said her students didn't use the near-the-heart-and-bmi version during class use.

-On the heart attack, the message also does not come up for this right away (above even 50% fat).
    >>NP My bad - I had p_0 set to 0. In that case, the warning did not come up. When I set p_0 to non-zero it worked (but there was a slight delay for %fat above 30%).
    >>SR: I can't reproduce this delay.  Can you confirm the steps to repeat this problem?  Prehaps the problem is just that thresholds are 25/32% (male/female)

Need explanations for different activity levels from Noah
    >>Come up with definitions for different lifestyles

Fix text for "simulation age out of range" message

Added calculation for body fat % based on height, weight and activity level
    >>SR: Perhaps this should be a relative model instead of an absolute model so that changes are tracked
    >> and so that making a minor modification to one parameter doesn't dramatically change the body fat %